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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 18 Sep 2020 at 01:34 Created: 


Wikipedia: Biofilm A biofilm is any group of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPS). The EPS components are produced by the cells within the biofilm and are typically a polymeric conglomeration of extracellular DNA, proteins, and polysaccharides. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, biofilms are frequently described metaphorically as cities for microbes. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium. Biofilms can be present on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease. Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.

Created with PubMed® Query: biofilm[title] NOT 28392838[PMID] NOT 31293528[PMID] NOT 29372251[PMID] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)


RevDate: 2020-09-17

Alvendal C, Mohanty S, Bohm-Starke N, et al (2020)

Anti-biofilm activity of chlorhexidine digluconate against Candida albicans vaginal isolates.

PloS one, 15(9):e0238428 pii:PONE-D-20-07607.

OBJECTIVES: Recurrent vulvovaginal candidiasis (RVVC) causes significant morbidity. Candida albicans is the main pathogen associated with both sporadic and recurrent candidiasis. Due to unsatisfactory treatment effect, the impact of chlorhexidine digluconate and fluconazole alone or in combination on C. albicans and biofilm was investigated.

METHODS: Vaginal C. albicans isolates from 18 patients with recurrent candidiasis and commensals from 19 asymptomatic women were isolated by culture. Crystal violet, XTT and colony forming unit assay were used to analyze the effect of chlorhexidine digluconate and fluconazole on growth of C. albicans, formation of new and already established, mature, biofilm.

RESULTS: Fluconazole reduced the growth of planktonic C. albicans. However, in established biofilm, fluconazole had no effect on the candida cells and was not able to disperse and reduce the biofilm. By contrast, chlorhexidine digluconate had a direct killing effect on C. albicans grown both planktonically and in biofilm. Chlorhexidine digluconate also dispersed mature biofilm and inhibited formation of new biofilm. No major differences were observed between commensal isolates and candida causing recurrent vulvovaginitis with respect to biofilm or growth after chlorhexidine digluconate treatment.

CONCLUSION: Biofilm is a problem in patients with recurrent vulvovaginal candidiasis reducing the effect of antifungal treatment. Development of new treatment strategies are urgently needed to decrease the recurrences. In already established biofilm, chlorhexidine digluconate dispersed the biofilm and was more effective in eradicating candida compared to fluconazole. Future treatment strategy may thus be a combination of chlorhexidine digluconate and fluconazole and prophylactic use of chlorhexidine digluconate to prevent biofilm formation and restrict infections.

RevDate: 2020-09-17

Liang M, Wang Y, Ma K, et al (2020)

Engineering Inorganic Nanoflares with Elaborate Enzymatic Specificity and Efficiency for Versatile Biofilm Eradication.

Small (Weinheim an der Bergstrasse, Germany) [Epub ahead of print].

Nanozyme has emerged as a versatile nanocatalyst yet is constrained with limited catalytic efficiency and specificity for various biomedical applications. Herein, by elaborately integrating the recognition/transduction carbon dots (CDs) with platinum nanoparticles (PtNPs), an exquisite CDs@PtNPs (CPP) nanoflare is engineered as an efficient and substrate-specific peroxidase-mimicking nanozyme for high-performance biosensing and antibacterial applications. The intelligent CPP-catalyzed hydrogen peroxide (H2 O2)-generated reactive oxygen species realize the sensitive diagnosis-guided enhanced disinfection of pathogens. Significantly, the CPP nanozyme shows the prominent biofilm eradication and wound healing in vivo by virtue of endogenous H2 O2 in acidic infection tissues, which can substantially preclude the annoying antibiotics resistance. A fundamental understanding on the present CPP nanoflare would not only facilitate the advancement of various prospective biocatalysts, but also establish a multifunctional means for versatile biosensing and smart diagnostic applications.

RevDate: 2020-09-17

Steiger EL, Muelli JR, Braissant O, et al (2020)

Effect of divalent ions on cariogenic biofilm formation.

BMC microbiology, 20(1):287 pii:10.1186/s12866-020-01973-7.

BACKGROUND: Divalent cations are able to interact with exopolysaccharides (EPS) and thus are capable to modify the structure and composition of dental biofilm. At the moment, little is known about the adsorption of metals by cariogenic EPS; thus, the aim of the present study was to evaluate the effect of divalent ions (calcium, magnesium, and zinc) on the growth and biofilm formation of mutans streptococci and on the dissolution of hydroxyapatite as well as to investigate their binding to the bacterial EPS.

RESULTS: S. mutans strains used in this study show the highest tolerance towards calcium of the ions tested. Growth parameters showed no differences to control condition for both strains up to 100 mM; revealing natural tolerance to higher concentration of calcium in the surroundings. Although excessive levels of calcium did not impair the growth parameters, it also did not have a positive effect on biofilm formation or its binding affinity to EPS. Magnesium-saturated environment proved to be counterproductive as strains were able to dissolve more Ca2+ from the tooth surface in the presence of magnesium, therefore releasing excessive amounts of Ca2+ in the environment and leading to the progression of the disease. Thus, this supports the idea of self-regulation, when more Ca2+ is released, more calcium is bound to the biofilm strengthening its structure and however, also less is left for remineralization. Zinc inhibited bacterial adhesion already at low concentrations and had a strong antibacterial effect on the strains as well as on calcium dissolution; leading to less biofilm and less EPS. Additionally, Zn2+ had almost always the lowest affinity to all EPS; thus, the unbound zinc could also still remain in the surrounding environment and keep its antimicrobial properties.

CONCLUSION: It is important to maintain a stable relationship between calcium, magnesium and zinc as excessive concentrations of one can easily destroy the balance between the three in cariogenic environment and lead to progression of the disease.

RevDate: 2020-09-17

Ribeiro-Vidal H, Sánchez MC, Alonso-Español A, et al (2020)

Antimicrobial Activity of EPA and DHA against Oral Pathogenic Bacteria Using an In Vitro Multi-Species Subgingival Biofilm Model.

Nutrients, 12(9): pii:nu12092812.

In search for natural products with antimicrobial properties for use in the prevention and treatment of periodontitis, the purpose of this investigation was to evaluate the antimicrobial activity of two omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), using an in vitro multi-species subgingival biofilm model including Streptococcus oralis, Actinomyces naeslundii, Veillonella parvula, Fusobacterium nucleatum, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans. The antimicrobial activities of EPA and DHA extracts (100 µM) and the respective controls were assessed on 72 h biofilms by their submersion onto discs for 60 s. Antimicrobial activity was evaluated by quantitative polymerase chain reaction (qPCR), confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). ANOVA with Bonferroni correction was used to evaluate the antimicrobial activity of each of the fatty acids. Both DHA and EPA significantly reduced (p < 0.001 in all cases) the bacterial strains used in this biofilm model. The results with CLSM were consistent with those reported with qPCR. Structural damage was evidenced by SEM in some of the observed bacteria. It was concluded that both DHA and EPA have significant antimicrobial activity against the six bacterial species included in this biofilm model.

RevDate: 2020-09-17

Su JF, Wu ZZ, Huang TL, et al (2020)

A new technology for simultaneous calcium-nitrate and fluoride removal in the biofilm reactor.

Journal of hazardous materials, 399:122846.

In this study, a biofilm reactor containing Acinetobacter sp.H12 was established to investigate the simultaneous denitrification, the removal of calcium and fluoride performance. The main precipitation components in the reactor were determined by SEM, XPS and XRD. The effects of HRT (6 h, 9 h and 12 h), pH (6.0, 7.0, 8.0), influent F- concentration (3 mg/L, 5 mg/L, 10 mg/L) on synchronously removal of nitrate and F- and Ca2+ during reactor operation were studied. Optimum operating conditions were achieved with a nitrate removal ratio of 100%, F- removal ratio of 81.91% and Ca2+ removal ratio of 67.66%. Nitrogen was the main gaseous product analyzed by gas chromatography. Extracellular polymers (proteins) were also identified as sites for biological precipitation nucleation by fluorescence spectroscopy. Moreover, microbial distribution and community structure analysis showed that strain H12 was the dominat strain in the biofilm reactor. And combined with the performance prediction of the reactor, strain H12 played a major role in the process of simultaneous denitrification, F- and Ca2+ removal.

RevDate: 2020-09-16

Gilbertie JM, Levent G, Norman KN, et al (2020)

Comprehensive phenotypic and genotypic characterization and comparison of virulence, biofilm, and antimicrobial resistance in urinary Escherichia coli isolated from canines.

Veterinary microbiology, 249:108822 pii:S0378-1135(20)30960-3 [Epub ahead of print].

Urinary tract infections (UTIs) affect nearly half of women and an estimated 14 % of the canine companion animal population at least once in their lifetime. As with humans, Escherichia coli is the most commonly isolated bacteria from canine UTIs and infections are dominated by specific phylogenetic groups with notable virulence attributes. In this study, we evaluated uropathogenic E. coli (UPEC) (n = 69) isolated from canine UTIs phenotypically and genotypically for virulence factors, biofilm formation and antimicrobial resistance profiles. Biofilm formation in UPEC strains was positively associated with common virulence factors including papG (p = 0.006), fimH (p < 0.0001), sfaS (p = 0.004), focA (p = 0.004), cnf-1 (p = 0.009) and hlyA (p = 0.006). There was a negative association between biofilm formation and phenotypic antimicrobial resistance for ampicillin (p < 0.0004), ciprofloxacin (p < 0.0001), and trimethoprim-sulfamethoxazole (p < 0.02), as well as multidrug resistance (isolates resistant to ≥ 3 classes of antimicrobials) (p < 0.0002), and the presence of extended spectrum beta-lactamase (ESBL)-producing genes (p < 0.05). In conclusion, UPECs isolated from clinical cases of canine UTIs show a broad negative association between antimicrobial resistance and biofilm formation, and this observation is supported both by phenotypic and genotypic endpoints. As the biofilm formation may result in antimicrobial tolerance, this could be a secondary evasive tactic of UPEC lacking traditional antimicrobial resistance traits. This observation is important for veterinary practitioners to consider when treating puzzling chronic intractable and/or recurrent cases of UTI that appear to be susceptible to antimicrobial therapy via traditional antimicrobial susceptibility testing (AST) methods.

RevDate: 2020-09-16

Wakade VS, P Shende (2020)

Strategic advancements and multimodal applications of biofilm therapy.

Expert opinion on biological therapy [Epub ahead of print].

INTRODUCTION: Biofilm is a layer of mucilage consisting of bacterial species like Escherichia coli and Streptococcus aureus adhering to the solid cell surface. Biofilm is an important and novel approach in a delivery system comprising of six elements that includes extracellular DNA, enzymes, proteins, bacteria, exopolysaccharides and water channels. The biofilm formation is based on two mechanisms: extra polymeric substance and quorum sensing. The microbes present in biofilm prevent direct interaction between the cell surface and foreign materials, like allergens, or toxic gases, like carbon-monoxide and chlorofluorocarbon, entering the body.

AREAS COVERED: The authors focus on the novel applications of biofilms such as adhesives, tissue engineering, targeted delivery system, probiotics, nutrients delivery, etc. Moreover, the information of the factors for biofilm formation, techniques useful in biofilm formation and clinical studies are also covered in this article.

EXPERT OPINION: Many people believe that biofilms have a negative impact on human health, but the expert opinion states that biofilm is a futuristic approach useful in therapeutics for the treatment of tumours and cancer. Biofilms can be combined with novel delivery systems such as nanoparticles, microparticles, etc. for better therapeutic action.

RevDate: 2020-09-16

Chen H, Yang Y, Weir MD, et al (2020)

Regulating Oral Biofilm from Cariogenic State to Non-Cariogenic State via Novel Combination of Bioactive Therapeutic Composite and Gene-Knockout.

Microorganisms, 8(9): pii:microorganisms8091410.

The objectives were to investigate a novel combination of gene-knockout with antimicrobial dimethylaminohexadecyl methacrylate (DMAHDM) composite in regulating oral biofilm from a cariogenic state toward a non-cariogenic state. A tri-species biofilm model included cariogenic Streptococcus mutans (S. mutans), and non-cariogenic Streptococcus sanguinis (S. sanguinis) and Streptococcus gordonii (S. gordonii). Biofilm colony-forming-units (CFUs), lactic acid and polysaccharide production were measured. TaqMan real-time-polymerase-chain reaction was used to determine the percentage of each species in biofilm. The rnc gene-knockout for S. mutans with DMAHDM composite reduced biofilm CFU by five logs, compared to control (p < 0.05). Using parent S. mutans, an overwhelming S. mutans percentage of 68.99% and 69.00% existed in biofilms on commercial composite and 0% DMAHDM composite, respectively. In sharp contrast, with a combination of S. mutans rnc knockout and DMAHDM composite, the cariogenic S. mutans percentage in biofilm was reduced to only 6.33%. Meanwhile, the non-cariogenic S. sanguinis + S. gordonii percentage was increased to 93.67%. Therefore, combining rnc-knockout with bioactive and therapeutic dental composite achieved the greatest reduction in S. mutans, and the greatest increase in non-cariogenic species, thereby yielding the least lactic acid-production. This novel method is promising to obtain wide applications to regulate biofilms and inhibit dental caries.

RevDate: 2020-09-16

Usui Y, Shimizu T, Nakamura A, et al (2020)

Metabolites Produced by Kaistia sp. 32K Promote Biofilm Formation in Coculture with Methylobacterium sp. ME121.

Biology, 9(9): pii:biology9090287.

Previously, we reported that the coculture of motile Methylobacterium sp. ME121 and non-motile Kaistia sp. 32K, isolated from the same soil sample, displayed accelerated motility of strain ME121 due to an extracellular polysaccharide (EPS) produced by strain 32K. Since EPS is a major component of biofilms, we aimed to investigate the biofilm formation in cocultures of the two strains. The extent of biofilm formation was measured by a microtiter dish assay with the dye crystal violet. A significant increase in the amount of biofilm was observed in the coculture of the two strains, as compared to that of the monocultures, which could be due to a metabolite produced by strain 32K. However, in the coculture with strain 32K, using Escherichia coli or Pseudomonas aeruginosa, there was no difference in the amount of biofilm formation as compared with the monoculture. Elevated biofilm formation was also observed in the coculture of strain ME121 with Kaistia adipata, which was isolated from a different soil sample. Methylobacterium radiotolerans, isolated from another soil sample, showed a significant increase in biofilm formation when cocultured with K. adipata, but not with strain 32K. We also found that the culture supernatants of strains 32K and K. adipata accelerated the motility of strains ME121 and M. radiotolerans, wherein culture supernatant of K. adipata significantly increased the motility of M. radiotolerans, as compared to that by the culture supernatant of strain 32K. These results indicated that there was a positive relationship between accelerated motility and increased biofilm formation in Methylobacterium spp. This is the first study to report that the metabolites from Kaistia spp. could specifically modulate the biofilm-forming ability of Methylobacterium spp. Methylobacterium spp. biofilms are capable of inhibiting the biofilm formation of mycobacteria, which are opportunistic pathogens that cause problems in infectious diseases. Thus, the metabolites from the culture supernatant of Kaistia spp. have the potential to contribute to the environment in which increased biofilm production of Methylobacterium is desired.

RevDate: 2020-09-16

Mongaret C, Varin-Simon J, Lamret F, et al (2020)

Cutibacterium acnes Biofilm Study during Bone Cells Interaction.

Microorganisms, 8(9): pii:microorganisms8091409.

Cutibacterium acnes is an opportunistic pathogen involved in Bone and Prosthesis Infections (BPIs). In this study, we observed the behavior of commensal and BPI C. acnes strains in the bone environment through bacterial internalization by osteoblast-like cells and biofilm formation. For the commensal strains, less than 1% of the bacteria were internalized; among them, about 32.7 ± 3.9% persisted intracellularly for up to 48 h. C. acnes infection seems to have no cytotoxic effect on bone cells as detected by LDH assay. Interestingly, commensal C. acnes showed a significant increase in biofilm formation after osteoblast-like internalization for 50% of the strains (2.8-fold increase). This phenomenon is exacerbated on a titanium support, a material used for medical devices. For the BPI clinical strains, we did not notice any increase in biofilm formation after internalization despite a similar internalization rate by the osteoblast-like cells. Furthermore, fluorescent staining revealed more live bacteria within the biofilm after osteoblast-like cell interaction, for all strains (BPIs and commensal). The genomic study did not reveal any link between their clinical origin and phylotype. In conclusion, we have shown for the first time the possible influence of internalization by osteoblast-like cells on commensal C. acnes.

RevDate: 2020-09-16

Schestakow A, M Hannig (2020)

Effects of Experimental Agents Containing Tannic Acid or Chitosan on the Bacterial Biofilm Formation in Situ.

Biomolecules, 10(9): pii:biom10091315.

Chitosan and tannic acid are known for their antibacterial properties. In the present in-situ study, their antibacterial and anti-adherent effects on biofilm formation on enamel were investigated. Six subjects carried upper jaw splints with bovine enamel specimens, allowing in-situ biofilm formation. During the two-day trial, subjects rinsed with experimental solutions that contained either chitosan, tannic acid (pH = 2.5), tannic acid (pH = 7) or hydrochloric acid. Water served as the negative and chlorhexidine as the positive control. Rinsing occurred four or five times following two different rinsing protocols to investigate both the immediate and long-lasting effects. After 48 h of intraoral exposure, the dental plaque was stained with LIVE/DEAD® BacLight, and fluorescence micrographs were evaluated by using the software ImageJ. The results were verified by scanning electron microscopy. Rinsing with chitosan resulted in little immediate antibacterial and anti-adherent effects but failed to show any long-lasting effect, while rinsing with tannic acid resulted in strong immediate and long-lasting effects. Except for a slightly lower antibacterial effect, the neutral solution of tannic acid was as good as the acidic solution. Hydrochloric acid showed neither an antibacterial nor an anti-adherent effect on dental biofilm formation. Experimental solutions containing tannic acid are promising anti-biofilm agents, irrespective of the pH values of the solutions. Chitosan, on the other hand, was not able to prevent biofilm formation.

RevDate: 2020-09-15

Tang Q, Sheng Y, Li C, et al (2020)

Simultaneous removal of nitrate and sulfate using an up-flow three-dimensional biofilm electrode reactor: Performance and microbial response.

Bioresource technology, 318:124096 pii:S0960-8524(20)31369-9 [Epub ahead of print].

Nitrate removal from low carbon water is a problem in the water treatment, especially in the presence of high sulfate. In this work, an up-flow three-dimensional biofilm electrode reactor (3D-BER) was established to remove nitrate and sulfate from low organic carbon water. Results indicated that sulfate negatively affected nitrate removal. Moreover, high electric current and short hydraulic retention time deteriorated the performance of nitrate and sulfate removal. When the influent of SO42- was 150 mg/L, the removal efficiency of NO3--N and SO42- was 88.49 ± 4.5% and 29.35 ± 5.5%, respectively. The high-throughput sequencing revealed that denitrifying bacteria dominated in the lower part of the reactor while sulfate reducing bacteria dominated in the upper part of the reactor. It was speculated that oxidation products of sulfide could serve as supplementary electron donors to enhance nitrate removal in the 3D-BER.

RevDate: 2020-09-15

Vijayakumar K, Manigandan V, Jeyapragash D, et al (2020)

Eucalyptol inhibits biofilm formation of Streptococcus pyogenes and its mediated virulence factors.

Journal of medical microbiology [Epub ahead of print].

Introduction.Streptococcus pyogenes is a diverse virulent synthesis pathogen responsible for invasive systemic infections. Establishment of antibiotic resistance in the pathogen has produced a need for new antibiofilm agents to control the biofilm formation and reduce biofilm-associated resistance development.Aim. The present study investigates the in vitro antibiofilm activity of eucalyptol against S. pyogenes.Methodology. The antibiofilm potential of eucalyptol was assessed using a microdilution method and their biofilm inhibition efficacy was visualized by microscopic analysis. The biochemical assays were performed to assess the influence of eucalyptol on virulence productions. Real-time PCR analysis was performed to evaluate the expression profile of the virulence genes.Results. Eucalyptol showed significant antibiofilm potential in a dose-dependent manner without affecting bacterial growth. Eucalyptol at 300 µg ml-1 (biofilm inhibitory concentration) significantly inhibited the initial stage of biofilm formation in S. pyogenes. However, eucalyptol failed to diminish the mature biofilms of S. pyogenes at biofilm inhibitory concentration and it effectively reduced the biofilm formation on stainless steel, titanium, and silicone surfaces. The biochemical assay results revealed that eucalyptol greatly affects the cell-surface hydrophobicity, auto-aggregation, extracellular protease, haemolysis and hyaluronic acid synthesis. Further, the gene-expression analysis results showed significant downregulation of virulence gene expression upon eucalyptol treatment.Conclusion. The present study suggests that eucalyptol applies its antibiofilm assets by intruding the initial biofilm formation of S. pyogenes. Supplementary studies are needed to understand the mode of action involved in biofilm inhibition.

RevDate: 2020-09-16

Zhang Y, Pi Y, Hua Y, et al (2020)

Bacteria responsive polyoxometalates nanocluster strategy to regulate biofilm microenvironments for enhanced synergetic antibiofilm activity and wound healing.

Theranostics, 10(22):10031-10045.

Backgroud: Nowadays, biofilms that are generated as a result of antibiotic abuse cause serious threats to global public health. Such films are the primary factor that contributes to the failure of antimicrobial treatment. This is due to the fact that the films prevent antibiotic infiltration, escape from innate immune attacks by phagocytes and consequently generate bacterial resistance. Therefore, exploiting novel antibacterial agents or strategies is extremely urgent. Methods: Herein, we report a rational construction of a novel biofilm microenvironment (BME)-responsive antibacterial platform that is based on tungsten (W)-polyoxometalate clusters (POMs) to achieve efficient bactericidal effects. Results: On one hand, the acidity and reducibility of a BME could lead to the self-assembly of POMs to produce large aggregates, which favor biofilm accumulation and enhance photothermal conversion under near-infrared (NIR) light irradiation. On the other hand, reduced POM aggregates with BME-induced photothermal-enhanced efficiency also exhibit surprisingly high peroxidase-like activity in the catalysis of bacterial endogenous hydrogen peroxide (H2O2) to produce abundant reactive oxygen species (ROS). This enhances biofilm elimination and favors antibacterial effects. Most importantly, reduced POMs exhibit the optimal peroxidase-like activity in an acidic BME. Conclusion: Therefore, in addition to providing a prospective antibacterial agent, intelligent acid/reductive dual-responsive POMs will establish a new representative paradigm for the areas of healthcare with minimal side effects.

RevDate: 2020-09-15

Slipski CJ, Jamieson TR, Zhanel GG, et al (2020)

Riboswitch associated guanidinium selective efflux pumps frequently transmitted on proteobacterial plasmids increase Escherichia coli biofilm tolerance to disinfectants.

Journal of bacteriology pii:JB.00104-20 [Epub ahead of print].

Members of the small multidrug resistant (SMR) efflux pump family known as SugE (more recently renamed to Gdx) are known for their narrow substrate selectivity to small guanidinium (Gdm+) compounds and disinfectant quaternary ammonium compounds (QACs). Gdx members have been identified on multidrug resistant plasmids in Gram-negative bacilli, but their functional role remains unclear as few have been characterized. Here, we conducted a survey of sequenced proteobacterial plasmids that encoded one or more SugE/Gdx sequences in an effort to 1) identify the most frequently represented Gdx member(s) on these plasmids and their sequence diversity, 2) verify if Gdx sequences possess a Gdm+ riboswitch that regulates their translation similar to chromosomally encoded Gdx members, and 3) determine the antimicrobial susceptibility profile of the most predominate Gdx member to various QACs and antibiotics in E. coli strains, BW25113 and KAM32. The results of this study determined 14 unique SugE sequences, but only one Gdx sequence annotated as 'SugE(p)' predominated among the >140 plasmids we surveyed. Enterobacterales plasmids encoding sugE(p) possessed a Guanidine-II riboswitch similar to the upstream region of E. coligdx Cloning and expression of sugE(p), gdx, and emrE sequences into a low copy expression vector (pMS119EH) revealed significant increases in QAC resistance to a limited range of detergent-like QACs only when gdx and sugE(p) transformants were grown as biofilms. These findings suggest that sugE(p) presence on proteobacterial plasmids may be driven by species that frequently encounter Gdm+ and QAC exposure.Importance: This study characterized the function of antimicrobial-resistant phenotypes attributed to plasmid encoded guanidinium selective small multidrug resistant (gdm/sugE) efflux pumps. These sequences are frequently monitored as biocide-resistance markers in antimicrobial resistance surveillance studies. Our findings reveal that Enterobacterial gdm sequences transmitted on plasmids possess a Guanidine-II riboswitch, which restricts transcript translation in the presence of guanidinium. Cloning and overexpression of this gdm sequence revealed that it confers higher resistance to quaternary ammonium compound (QAC) disinfectants (that possess guanidium moieties) when grown as biofilms. Since biofilms are commonly eradicated with QAC containing compounds the presence of this gene on plasmids and its biofilm-specific resistance are a growing concern to clinical and food safety prevention measures.

RevDate: 2020-09-15

Leão C, Borges A, M Simões (2020)

NSAIDs as a Drug Repurposing Strategy for Biofilm Control.

Antibiotics (Basel, Switzerland), 9(9): pii:antibiotics9090591.

Persistent infections, usually associated with biofilm-producing bacteria, are challenging for both medical and scientific communities. The potential interest in drug repurposing for biofilm control is growing due to both disinvestment in antibiotic R&D and reduced efficacy of the available panel of antibiotics. In the present study, the antibacterial and antibiofilm activities of four non-steroidal anti-inflammatory drugs (NSAIDs), piroxicam (PXC), diclofenac sodium (DCF), acetylsalicylic acid (ASA) and naproxen sodium (NPX) were evaluated against Escherichia coli and Staphylococcus aureus. The minimum inhibitory/bactericidal concentrations (MICs and MBCs) and the dose-response curves from exposure to the selected NSAIDs were determined. MICs were found for PXC (800 μg/mL) and ASA (1750 μg/mL) against E. coli, and for DCF (2000 μg/mL) and ASA (2000 μg/mL) against S. aureus. No MBCs were found (>2000 μg/mL). The potential of NSAIDs to eradicate preformed biofilms was characterized in terms of biofilm mass, metabolic activity and cell culturability. Additionally, the NSAIDs were tested in combination with kanamycin (KAN) and tetracycline (TET). ASA, DCF and PXC promoted significant reductions in metabolic activity and culturability. However, only PXC promoted biofilm mass removal. Additive interactions were obtained for most of the combinations between NSAIDs and KAN or TET. In general, NSAIDs appear to be a promising strategy to control biofilms as they demonstrated to be more effective than conventional antibiotics.

RevDate: 2020-09-14

Rasapalli S, Murphy ZF, Reddy Sammeta V, et al (2020)

Synthesis and Biofilm Inhibition Studies of 2-(2-amino-6-arylpyrimidin-4-yl)quinazolin-4(3H)-ones.

Bioorganic & medicinal chemistry letters pii:S0960-894X(20)30661-2 [Epub ahead of print].

Synthesis of novel 4(3H)-quinazolinonyl aminopyrimidine derivatives has been achieved via quinazolin only enones which in turn were obtained from 2-acyl-4(3H)-quinazolinone. They have been assayed for biofilm inhibition against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria (Acinetobacter baumannii). The analogues with 2,4,6-trimethoxy phenyl, 4-methylthio phenyl, and 3-bromo phenyl substituents (5h, 5j &5k) have been shown to inhibit biofilm formation efficiently in MRSA with IC50 values of 20.7-22.4 μM). The analogues 5h and 5j have demonstrated low toxicity in human cells in vitro and can be investigated further as leads.

RevDate: 2020-09-14

Chitrakar I, Iuliano JN, He Y, et al (2020)

Structural basis for the regulation of biofilm formation and iron uptake in A. baumannii by the blue-light using photoreceptor, BlsA.

ACS infectious diseases [Epub ahead of print].

The opportunistic human pathogen, A. baumannii, senses and responds to light using the blue light sensing A (BlsA) photoreceptor protein. BlsA is a Blue Light Using FAD (BLUF) that is known to regulate a wide variety of cellular functions through interactions with different binding partners. Using immunoprecipitation of tagged BlsA in A. baumannii lysates, we observed a number of proteins that interact with BlsA, including several transcription factors. In addition to a known binding partner, the iron uptake regulator Fur, we identified the biofilm response regulator BfmR as a putative BlsA binding partner. Using microscale thermophoresis, we determined that both BfmR and Fur bind to BlsA with nanomolar binding constants. To better understand how BlsA interacts with and regulates these transcription factors, we solved the X-ray crystal structures of BlsA in both a ground (dark) state and a photo-activated light state. Comparison of the light- and dark-state structures revealed that, upon photoactivation, the two α-helices comprising the variable domain of BlsA undergo a distinct conformational change. The flavin binding site, however, remains largely unchanged from dark to light. These structures, along with docking studies of BlsA and Fur, reveal key mechanistic details about how BlsA propagates the photoactivation signal between protein domains and on to its binding partner. Taken together, our structural and biophysical data provide important insights into how BlsA controls signal transduction in A. baumannii and provides a likely mechanism for blue-light dependent modulation of biofilm formation and iron uptake.

RevDate: 2020-09-14

Aleksandrowicz P, Brzezińska-Błaszczyk E, Dudko A, et al (2020)

Archaea Occurrence in the Subgingival Biofilm in Patients with Peri-implantitis and Periodontitis.

The International journal of periodontics & restorative dentistry, 40(5):677-683.

This study aimed to determine the prevalence and diversity of archaea and select bacteria in the subgingival biofilm of patients with peri-implantitis in comparison to patients with unaffected implants and patients with periodontitis. Samples of subgingival biofilm from oral sites were collected for DNA extraction (n = 139). A 16S rRNA gene-based polymerase chain reaction assay was used to determine the presence of archaea and select bacteria. Seven samples were selected for direct sequencing. Archaea were detected in 10% of samples from peri-implantitis sites, but not in samples from the unaffected dental implant. Archaea were present in 53% and 64% of samples from mild and moderate/advanced periodontitis sites, respectively. The main representative of the Archaea domain found in biofilm from periodontitis and peri-implantitis sites was Methanobrevibacter oralis. The present results revealed that archaea are present in diseased but not healthy implants. It was also found that archaea were more abundant in periodontitis than in peri-implantitis sites. Hence, the potential role of archaea in peri-implantitis and periodontitis should be taken into consideration.

RevDate: 2020-09-14

Meiers J, Zahorska E, Röhrig T, et al (2020)

Directing Drugs to Bugs: Antibiotic-Carbohydrate Conjugates targeting Biofilm-associated Lectins of Pseudomonas aeruginosa.

Journal of medicinal chemistry [Epub ahead of print].

Chronic infections by Pseudomonas aeruginosa are characterised by biofilm formation which effectively enhances resistance towards antibiotics. Biofilm-specific antibiotic delivery could locally increase drug concentration to break antimicrobial resistance and reduce the drug's peripheral side effects. Two extracellular P. aeruginosa lectins, LecA and LecB, are essential structural components for biofilm formation and thus render a possible anchor for biofilm-targeted drug delivery. The standard-of-care drug ciprofloxacin suffers from severe systemic side effects and was therefore chosen for this approach. We synthesized several ciprofloxacin-carbohydrate conjugates and established a structure-activity relationship. Conjugation of ciprofloxacin to lectin probes enabled biofilm accumulation in vitro, reduced the antibiotic's cytotoxicity, but also reduced its antibiotic activity against planktonic cells due to a reduced cell permeability and on target activity. This work defines the starting point for new biofilm/lectin-targeted drugs to modulate antibiotic properties and ultimately break antimicrobial resistance.

RevDate: 2020-09-14

Abdalla MM, Ali IAA, Khan K, et al (2020)

The Influence of Surface Roughening and Polishing on Microbial Biofilm Development on Different Ceramic Materials.

Journal of prosthodontics : official journal of the American College of Prosthodontists [Epub ahead of print].

PURPOSE: To test the hypothesis that surface roughening and polishing of ceramics have no effect on their surface roughness and biofilm adhesion.

MATERIALS AND METHODS: Feldspathic ceramic Vitablocks™ TriLuxe forte (VTF), lithium disilicate glass IPS e.max Press™ (IPS) and zirconia reinforced lithium silicate Vita Suprinity™ (VS) ceramic blocks (n = 27 per group) were prepared from sintered CAD blocks using a water-cooled saw. They were further subdivided into 3 subgroups according to the surface treatment protocols (n = 9): as prepared, roughened and polished. The surface roughness of the ceramic blocks was measured using an electro-mechanical profilometer. The ceramic sections were inoculated with Streptococcus mutans and incubated for 48 h to form a biofilm. The ceramic surfaces with the biofilms were analyzed using Confocal Laser Scanning Microscopy to calculate the percentage of live bacteria and substratum coverage by the biofilm, and further visualized using scanning electron microscopy. Statistical analysis was done with SPSS software using two-way ANOVA, followed by post hoc Bonferroni test to identify significant differences between the groups. The level of significance was set at p = 0.05.

RESULTS: As prepared VTF showed significantly higher mean surface roughness values than as prepared IPS and VS. The mean percentage of live bacteria and biofilm coverage of the substrate were significantly higher in the roughened ceramic blocks than the as prepared and polished blocks for all three ceramic types (p < 0.05). Polished specimens of VS significantly lower percentage of biofilm coverage than the other groups (p < 0.05).

CONCLUSIONS: This study sheds new light that adjustments of ceramic restorations prior to cementation increases the likelihood for formation and adhesion of microbial biofilms on the surface. Polished zirconia reinforced lithium disilicate ceramics demonstrated the lowest bacterial adhesion among the evaluated ceramics. This article is protected by copyright. All rights reserved.

RevDate: 2020-09-14

Cholo MC, Rasehlo SSM, Venter E, et al (2020)

Effects of Cigarette Smoke Condensate on Growth and Biofilm Formation by Mycobacterium tuberculosis.

BioMed research international, 2020:8237402.

Materials and Methods: The planktonic and biofilm-forming cultures were prepared in Middlebrook 7H9 and Sauton broth media, respectively, using Mtb strain, H37Rv. The effects of CSC at concentrations of 0.05-3.12 mg/L on growth, biofilm formation and structure were evaluated using microplate Alamar Blue assay, spectrophotometric procedure and scanning electron microscopy (SEM), respectively. Involvement of reactive oxygen species in CSC-mediated biofilm formation was investigated by including catalase in biofilm-forming cultures.

Results: CSC did not affect the growth of planktonic bacteria, but rather led to a statistically significant increase in biofilm formation at concentrations of 0.4-3.12 mg/L, as well as in the viability of biofilm-forming bacteria at CSC concentrations of 0.2-1.56 mg/L. SEM confirmed an agglomerated biofilm matrix and irregular bacterial morphology in CSC-treated biofilms. Inclusion of catalase caused significant attenuation of CSC-mediated augmentation of biofilm formation by Mtb, implying involvement of oxidative stress. These findings demonstrate that exposure of Mtb to CSC resulted in increased biofilm formation that appeared to be mediated, at least in part, by oxidative stress, while no effect on planktonic cultures was observed.

Conclusion: Smoking-related augmentation of biofilm formation by Mtb may contribute to persistence of the pathogen, predisposing to disease reactivation and counteracting the efficacy of antimicrobial chemotherapy.

RevDate: 2020-09-14

Wasfi R, Hamed SM, Amer MA, et al (2020)

Proteus mirabilis Biofilm: Development and Therapeutic Strategies.

Frontiers in cellular and infection microbiology, 10:414.

Proteus mirabilis is a Gram negative bacterium that is a frequent cause of catheter-associated urinary tract infections (CAUTIs). Its ability to cause such infections is mostly related to the formation of biofilms on catheter surfaces. In order to form biofilms, P. mirabilis expresses a number of virulence factors. Such factors may include adhesion proteins, quorum sensing molecules, lipopolysaccharides, efflux pumps, and urease enzyme. A unique feature of P. mirabilis biofilms that build up on catheter surfaces is their crystalline nature owing to their ureolytic biomineralization. This leads to catheter encrustation and blockage and, in most cases, is accompanied by urine retention and ascending UTIs. Bacteria embedded in crystalline biofilms become highly resistant to conventional antimicrobials as well as the immune system. Being refractory to antimicrobial treatment, alternative approaches for eradicating P. mirabilis biofilms have been sought by many studies. The current review focuses on the mechanism by which P. mirabilis biofilms are formed, and a state of the art update on preventing biofilm formation and reduction of mature biofilms. These treatment approaches include natural, and synthetic compounds targeting virulence factors and quorum sensing, beside other strategies that include carrier-mediated diffusion of antimicrobials into biofilm matrix. Bacteriophage therapy has also shown successful results in vitro for combating P. mirabilis biofilms either merely through their lytic effect or by acting as facilitators for antimicrobials diffusion.

RevDate: 2020-09-14

Verma P, S Anand (2020)

Antimicrobial activity as a potential factor influencing the predominance of Bacillus subtilis within the constitutive microflora of a whey reverse osmosis membrane biofilm.

Journal of dairy science pii:S0022-0302(20)30695-0 [Epub ahead of print].

Current cleaning and sanitation protocols may not be adequately effective in cleaning separation membranes and can result in the formation of resilient multispecies biofilms. The matured biofilms may result in a bacterial predominance with resilient strains on membranes with a prolonged use. In our previous study, we isolated organisms such as Bacillus subtilis, Bacillus licheniformis, Exiguobacterium aurantiacum, and Acinetobacter radioresistens from an 18-mo-old reverse osmosis membrane. The competitive exclusion studies revealed the predominance of B. subtilis within the membrane biofilm microflora. This study investigated the antimicrobial activity of the B. subtilis isolate as a potential cause of its predominance. The culture isolate was propagated in tryptic soy broth at 37°C, and microfiltered to prepare cell-free extracts (CFE) at 8-, 10-, 12-, 14-, 16-, and 18-h intervals. The CFE were freeze-dried and suspended in minimum quantities of HPLC-grade water to prepare concentrated solutions. The antimicrobial activities of CFE were tested using the agar-well assay against the biofilm constitutive microflora. The experiments were conducted in triplicates and means were compared for significant differences using a general linear mixed model procedure. The results indicated the highest antimicrobial activity of 12-h CFE of B. subtilis against other constitutive microflora such as Exiguobacterium sp., E. auranticum, and A. radioresistens, with average inhibition zone sizes of 16.5 ± 0.00, 16.25 ± 0.66, and 20.6 ± 0.00 mm, respectively. Upon treatment with proteinase K, the CFE completely lost its antimicrobial activity, establishing it to be a proteinaceous compound. The AA profiling revealed the total crude protein in CFE to be 51% (wt/wt), with its major constituent as glutamic acid (11.30% wt/wt). The freeze-dried CFE was thermally stable on exposure to the common temperature used for sanitizer applications (23.8°C for 5 and 10 min) and over a pH range of 3.0 to 6.3. The study helped us understand the role of the antimicrobial compound produced by B. subtilis as a potential cause of its predominance within the biofilm constitutive microflora.

RevDate: 2020-09-14

Kaur T, Putatunda C, Vyas A, et al (2020)

Zinc oxide nanoparticles inhibit bacterial biofilm formation via altering cell membrane permeability.

Preparative biochemistry & biotechnology [Epub ahead of print].

In the current scenario nanoparticles (NPs) have gained a breathtaking impetus due to their multidimensional applications in varied fields. In the present effort, biogenic synthesis of Zinc Oxide nanoparticles (ZnO NPs) was carried out using aqueous extract of dried powder of Emblica officinalis (Amla). Physicochemical characterization of nanoparticles was carried out via UV-Visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) wherein the particles were found to be quasi spherical and with a size ranging between 3 and 11 nm. The ZnO nanoparticles exhibited significant antibacterial activity against bacteria as Streptococcus pyogenes MTCC 442, Bacillus cereus MTCC 1272, Escherichia coli MTCC 1687 and Pseudomonas aeruginosa MTCC 4673. The nanoparticles displayed high anti-biofilm activity toward all the bacterial strains, when tested against three different base materials viz. glass, plastic and metal (Aluminum). Further, the nanoparticle treatment of bacterial cells caused changes in their cell membrane permeability, leading to leakage of nucleic acid from the bacterial cells, thereby defining it as the most probable mechanism for their anti-biofilm potential.

RevDate: 2020-09-13

Ali IAA, Cheung BPK, Matinlinna J, et al (2020)

Trans-cinnamaldehyde potently kills Enterococcus faecalis biofilm cells and prevents biofilm recovery.

Microbial pathogenesis pii:S0882-4010(20)30848-2 [Epub ahead of print].

Enterococcus faecalis is a biofilm-forming, nosocomial pathogen that is frequently isolated from failed root canal treatments. Contemporary root canal disinfectants are ineffective in eliminating these biofilms and preventing reinfection. As a result, there is a pressing need to identify novel and safe antibiofilm molecules. The effect of short-term (5 and 15 min) and long-term (24 h) treatments of trans-cinnamaldehyde (TC) on the viability of E. faecalis biofilms was compared with currently used root canal disinfectants. Treatment for 15 min with TC reduced biofilm metabolic activity as effective as 1% sodium hypochlorite and 2% chlorhexidine. Treatment with TC for 24 h was significantly more effective than 2% chlorhexidine in reducing the viable cell counts of biofilms. This serendipitous effect of TC was sustained for 10 days under growth-favoring conditions. For the first time, our study highlights the strong antibacterial activity of TC against E. faecalis biofilms, and notably, its ability to prevent biofilm recovery after treatment.

RevDate: 2020-09-13

Han H, Gao Y, Chai M, et al (2020)

Biofilm microenvironment activated supramolecular nanoparticles for enhanced photodynamic therapy of bacterial keratitis.

Journal of controlled release : official journal of the Controlled Release Society pii:S0168-3659(20)30530-7 [Epub ahead of print].

Infectious keratitis caused by bacterial biofilms is one of the main causes of corneal blindness, presenting a serious threat to public health. In this study, matrix metalloproteinase (MMP)-sensitive supramolecular nanoparticles (denoted as MMP-S NPs) were constructed for enhancing photodynamic antibacterial effect against biofilm-associated bacterial keratitis. MMP-S NPs were prepared by host-guest self-assembly of chlorin e6 (Ce6) conjugated β-cyclodextrin (β-CD) prodrug (β-CD-Ce6) and MMP-9-sensitive peptides (YGRKKKRRQRRR-GPLGVRG-EEEEEE) terminated with adamantane (ad) (ad-MMP-S PEPs). MMP-S NPs with EEEEEE peptide shell had a negatively charged surface, preventing adhesion to the normal ocular surface or healthy corneal cells, thus enhancing tear retention time. After arriving at the infected lesions, the protective EEEEEE peptide shell of MMP-S NPs was removed, triggered by overexpressed MMP-9 in the keratitis microenvironment. The subsequently exposed cationic peptides helped the nanoparticles penetrate and accumulate in biofilms as well as bind to gram-negative bacteria Pseudomonas aeruginosa (P. aeruginosa), which eventually improved the photodynamic antibacterial effect. Furthermore, the P. aeruginosa keratitis model verified the high effectiveness of a topical eye drop formulation of MMP-S NPs in killing bacteria by destroying the bacterial membrane as a result of in situ photodynamic activation of reactive oxygen species (ROS) formation under light irradiation. Moreover, the inflammatory response in the cornea was inhibited to a great extent. As a result, further damage to the corneal tissue was completely suppressed. This research provides a viable antibacterial alternative to fight against bacterial keratitis through effective elimination of infectious bacteria and eradication of bacterial biofilms in the cornea.

RevDate: 2020-09-12

Kavita S, Pooranachithra M, Singh N, et al (2020)

Lactobacillus gastricus BTM 7 prevents intestinal colonization by biofilm forming Cronobacter sakazakii in Caenorhabditis elegans model host.

Antonie van Leeuwenhoek pii:10.1007/s10482-020-01466-7 [Epub ahead of print].

The study reports protective role of potential probiotic cultures against infection by biofilm forming Cronobacter sakazakii in Caenorhabditis elegans model system. Among the fifteen indigenous potential probiotics, the cell free supernatant of Lactobacillus gastricus BTM7 possessed highest antimicrobial action and biofilm inhibition against C. sakazakii. The competitive exclusion assays revealed that preconditioning with probiotics resulted in increased mean life span of the nematode to 12-13 days as compared to 5-6 days when the pathogen was administered alone. Enhanced expression of the marker genes (pmk-1, daf-16 and skn-1) was observed during the administration of probiotic cultures. The highest expression of pmk-1 (2.5 folds) was observed with administration of L. gastricus BTM7. The principal component analysis on selected variables revealed that L. gastricus BTM7 has the potential to limit the infection of C. sakazakii in C. elegans and enhance the expression of key genes involved in extending life span of the worm.

RevDate: 2020-09-12

Kurakado S, Miyashita T, Chiba R, et al (2020)

Role of arthroconidia in biofilm formation by Trichosporon asahii.

Mycoses [Epub ahead of print].

BACKGROUND: Trichosporon asahii is the major causative agent of disseminated and deep-seated trichosporonosis. It is capable of forming biofilms on surfaces, leading to medical device-related infection. T. asahii may be present as yeast form, hyphae, and/or arthroconidia; however, the relationship between its biofilm-forming ability and its morphological transition is unclear.

OBJECTIVES: We investigated whether the T. asahii morphological transition contributes to its biofilm formation. We also determined the conditions required to induce each of the morphologies.

METHODS: Three high- and three low-biofilm-producing strains (HBS and LBS, respectively) were selected using a biofilm formation assay, and the cell-surface hydrophobicity of these six strains was measured. For each strain, the morphology was observed and the number of each morphological form (yeast form, hypha and arthroconidium) was counted to calculate of the ratio. Finally, the ability of cells each morphological type to adhere to the polystyrene substrate was evaluated.

RESULTS: The HBS exhibited abundant arthroconidia and hyphae; in contrast, the LBS produced mainly hyphae with few or no arthroconidia. The production of hyphae was increased by nitrogen-containing medium, and the production of arthroconidia was increased by nitrogen-deficient medium. Cells incubated under nitrogen-deficient conditions showed higher adherence to a polystyrene surface than those incubated in the presence of nitrogen.

CONCLUSION: Arthroconidia of T. asahii play a key role in biofilm formation by promoting cellular adhesion.

RevDate: 2020-09-12

de Sousa ET, Lima-Holanda AT, Sales LS, et al (2020)

Combined effect of starch and sucrose on carbonic anhydrase VI activity in saliva and biofilm of children with early childhood caries. Exposure to starch and sucrose alters carbonic anhydrase VI activity in saliva and biofilm.

Clinical oral investigations pii:10.1007/s00784-020-03567-z [Epub ahead of print].

OBJECTIVES: This study aimed to investigate whether combined exposure to starch and sucrose modifies the activity of carbonic anhydrase VI (CA VI) in saliva (Study 1) and biofilm (Study 2) of children with early childhood caries (ECC).

MATERIAL AND METHODS: For Study 1 and Study 2, respectively, 54 and 46 preschoolers aged 4 to 5 were allocated into two groups: caries-free (CF) and with ECC. Children were exposed to rinses with sucrose, starch, and sucrose plus starch solutions. CA VI activity, pH, and buffering capacity (BC) were evaluated in saliva and biofilm.

RESULTS: In Study 1, a significant reduction in saliva pH was observed after sucrose and sucrose plus starch rinses. CA VI activity was influenced by ECC independently of the type of carbohydrate to which children were exposed. CA VI activity was higher in children with ECC; however, after rinses, CA VI activity was reduced. In Study 2, biofilm pH and BC were reduced after rinses with sucrose and sucrose plus starch. CA VI activity was significantly high before rinse in ECC group when compared with CF group; however, no difference was observed between groups after rinses.

CONCLUSIONS: In saliva, exposure to starch and sucrose (isolated or combined) induced a reduction in CA VI activity in children with ECC. In biofilm, the combination of starch and sucrose did not modify CA VI activity in ECC children.

CLINICAL RELEVANCE: The responsivity of the CA VI reflects directly in important parameters related to the pH maintenance on the oral cavity.

RevDate: 2020-09-12

Keleş A, Keskin C, Kalkan M, et al (2020)

Visualization and characterization of Enterococcus faecalis biofilm structure in bovine dentin using 2D and 3D microscopic techniques.

Archives of microbiology pii:10.1007/s00203-020-02031-6 [Epub ahead of print].

Bacterial biofilms are related to various dental and periodontal infectious diseases, and the characterization of this biological structure with micro-computed tomography (micro-CT) may offer valuable information for clinical and research applications. In this study, we aimed to develop a model to visualize three-dimensionally the biofilm structure on dentin using micro-CT. Dentin blocks were prepared and incubated in tryptic soy broth with Enterococcus faecalis (ATCC 29212). The control group did not receive any staining procedure, while groups 1 and 2 were stained with 100% and 50% barium sulfate, respectively. Transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) were used to detect biofilm formation, barium sulfate penetration, and microbial cell density in the biofilm. Micro-computed tomography (micro-CT) (SkyScan 1172, Bruker Co., Belgium) was used to visualize biofilm formation on the dentin blocks. Biofilm thicknesses were measured from 10 different locations on the specimen surfaces, using CTAn v.1.14.4 software. Obtained data were statistically analyzed using Kruskal-Wallis and Dunn's tests. TEM photomicrographs showed that barium sulfate could penetrate the biofilm structure. CLSM analysis showed that viable and total cell densities were similar between the control and barium sulfate-treated groups (P > 0.05), indicating barium sulfate had no significant influence on cell density. In barium sulfate-treated blocks, biofilm could be discriminated from the dentin, and its thickness could be measured with micro-CT. This study showed that bacterial biofilm on dentin could be characterized by micro-CT after barium sulfate staining without causing any significant side effect on viable and total cell densities.

RevDate: 2020-09-12

Kim S, Li XH, Hwang HJ, et al (2020)

Thermoregulation of Biofilm Formation in Pseudomonas aeruginosa.

Applied and environmental microbiology pii:AEM.01584-20 [Epub ahead of print].

We investigated the temperature effect on the biofilm formation of P. aeruginosa and revealed that the biofilm formation increased rapidly at temperatures lower than 25°C. P. aeruginosa formed the most robust biofilm of conspicuous mushroom-like structure at 20°C. However, when the temperature increased to 25°C, the biofilm formation rapidly decreased. Above 25°C, as the temperature rose, the biofilm formation increased again little by little despite its less structured form, indicating that 25°C is the low point of biofilm formation. The intracellular c-di-GMP levels also decreased rapidly as the temperature rose from 20 to 25°C. The expression of pelA, algD, and pslA encoding Pel, alginate, and Psl, respectively, were also dramatically affected by temperature, in which pelA was regulated in a pattern such as a change in intracellular c-di-GMP levels and the regulation of algD was the most similar to the actual biofilm formation pattern. Total exopolysaccharide production was thermoregulated and followed the regulation pattern of c-di-GMP. Interestingly, the thermoregulation patterns in biofilm formation were different depending on the strain of P. aeruginosa Unlike PAO1, another strain PA14 showed a gradual decrease in biofilm formation and c-di-GMP in the range of 20 - 37°C and P. aeruginosa clinical isolates also showed slightly different patterns in biofilm formation with temperature change, suggesting that different strains may sense different temperature ranges for biofilm formation. However, it is obvious that P. aeruginosa forms more biofilms at lower temperatures and temperature is an important factor determining the biofilm formation.Importance Biofilm formation is an important protection mechanism used by most microorganisms and provides cells with many advantages like high infectivity, antibiotic resistance, and strong survivability. Since most persistent bacterial infections are believed to be associated with biofilms, the biofilm control is an important issue in medicine, environmental engineering, and industry. Biofilm formation is influenced by various environmental factors. Temperature is the most direct environmental cue encountered by microorganisms. Here we investigated the temperature effect on the biofilm formation of P. aeruginosa, a notorious pathogen, and found that temperature is an important factor determining the amount and structure of biofilm. Low temperature greatly increases the biofilm formation and gives it a highly conspicuous structure. Although the thermoregulation on biofilm formation is mainly mediated by c-di-GMP, some c-di-GMP-independent regulations were also observed. This study shows how biofilms are formed at various temperatures, and provides new insights to control biofilms using temperature.

RevDate: 2020-09-12

Rizzi A, Leroux J, Charron-Lamoureux V, et al (2020)

Bacillus subtilis modulates its usage of biofilm-bound iron in response to environmental iron availability.

Applied and environmental microbiology pii:AEM.00944-20 [Epub ahead of print].

Iron (Fe) is one of the most important micronutrients for most life forms on earth. While abundant in soil, Fe bioavailability in oxic soil is very low. In environmental conditions, bacteria need to acquire sufficient Fe to sustain growth while limiting the energy cost of siderophore synthesis. Biofilm formation might mitigate this Fe stress, since it was shown to accumulate Fe in certain Gram-negative bacteria and that this Fe could be mobilized for uptake. However, it is still unclear if and to what extent the amount of Fe accumulated in the biofilm can sustain growth, and if the mobilization of this local Fe pool is modulated by the availability of environmental Fe (i.e., Fe outside the biofilm matrix). Here we use a non-domesticated strain of the ubiquitous biofilm-forming soil bacterium, Bacillus subtilis, and stable Fe isotopes to precisely evaluate the origin of Fe during growth in the presence of tannic acid and hydroxides, used as proxies for different environmental conditions. We report that this B. subtilis strain can accumulate a large quantity of Fe in the biofilm, largely exceeding Fe associated with cells. We also report that only a fraction of biofilm-bound Fe is available for uptake in the absence of other sources of Fe in the vicinity of the biofilm. We observed that availability of environmental Fe modulates the usage of this pool of biofilm-bound Fe. Finally, our data suggest that consumption of biofilm-bound Fe relates to the efficacy of B. subtilis to transport Fe from the environment to the biofilm, possibly through siderophores.Importance Recent evidences suggest that Fe bound to the biofilm could assume at least two important functions; a local source of Fe for uptake and a support to extracellular metabolism such as extracellular electron transfer. Our results show that B. subtilis can use biofilm-bound Fe for uptake only if it does not compromise Fe homeostasis of the biofilm, i.e., maintaining a minimum Fe concentration in the biofilm for extracellular purposes. We propose a theoretical framework based on our results and recent literature to explain how B. subtilis manages biofilm-bound Fe and Fe uptake in response to environmental Fe availability. These results provide important insights into the management of biofilm-bound and environmental Fe by B. subtilis in response to Fe stress.

RevDate: 2020-09-12

Kim HW, Lee NY, Park SM, et al (2020)

A fast and effective alternative to a high-ethanol disinfectant: Low concentrations of fermented ethanol, caprylic acid, and citric acid synergistically eradicate biofilm-embedded methicillin-resistant Staphylococcus aureus.

International journal of hygiene and environmental health, 229:113586.

BACKGROUND: There is a growing need to develop a powerful bactericidal method with low ethanol concentrations due to the frequent ineffectiveness of traditional antibiotics against biofilms and the side effect of a high ethanol concentration.

OBJECTIVES: This study aims to develop a novel synergistic technique replacing a high-ethanol disinfectant.

METHODS: Low concentrations of fermented ethanol (FE, 10-20%) with naturally derived antimicrobials, citric acid (CTA, 0.5-1.0%) and caprylic acid (CAP, 0.05-0.15%), were examined against a methicillin-resistant S. aureus (MRSA) biofilm formed on silicone coupons (catheter materials).

RESULTS: CTA and CAP were identified as effective antimicrobials that exhibited a synergistic interaction with FE. Complete eradication of MRSA biofilms (>7 log reduction) was obtained within 5 min after treatment with 20% FE plus 1.0% CTA and 0.15% CAP at both 22 and 37 °C, while individual treatments with each material showed negligible bactericidal effects (<1 log reduction except 0.15% CAP treatment at 37 °C). No bacteria were recovered from the surface after the combined treatment (five enrichment tests). The developed compounds were able to disinfect surfaces with more than 5 log-reduction within only 1 min at 22 °C. Confocal microscopy images showed that the combination of all three materials resulted in remarkable membrane damage and cell detachment from the silicone surface.

DISCUSSON: Application of FE plus CTA and CAP, therefore, can be a valuable decontamination technique for medical devices or can work as a surface disinfectant, reducing the concerns regarding undesirable high ethanol concentrations in disinfectants.

RevDate: 2020-09-11

Svendsen SB, El-Taliawy H, Carvalho PN, et al (2020)

Concentration dependent degradation of pharmaceuticals in WWTP effluent by biofilm reactors.

Water research, 186:116389 pii:S0043-1354(20)30924-6 [Epub ahead of print].

Conventional wastewater treatment lacks the ability to remove many pharmaceuticals. This is leading to emissions to the natural aquatic environment, where these compounds pose a risk to the aquatic organisms. An advanced wastewater treatment technique that has shown promising results is Moving Bed Biofilm Reactors (MBBR). Initial degradation velocity and degradation rate constants of the pharmaceuticals are important parameters for designing an optimal MBBR system; however, the degradation efficiency varies across studies and one of the most plausible causes might be initial concentration. Thus, to verify the effect of initial concentration, the degradation of a mixture of 18 pharmaceuticals at different initial concentrations was studied. For this study MBBR's with very low BOD loading were used as they were conditioned with effluent water. The experiment was set up as a MBBR batch incubation, using effluent wastewater as medium, spiked with the 18 pharmaceuticals in seven different concentration levels (approximately 0-300 µg L-1). The degradation of 14 out of 18 pharmaceuticals was concentration-dependent. The initial degradation velocity of the pharmaceuticals was either proportional to the initial concentration or was following a typical Michaelis-Menten kinetic. The degradation velocity of one compound, i.e., sulfamethizole might have been inhibited at high concentrations. The degradation rate constants from single first-order fittings (KSFO) for some compounds deviated from the expected behavior at low concentrations (below 10 µg L-1). This is suggested to be caused by simplicity of the Michaelis-Menten model, not taking possible occurrence of co-metabolism and mass-transfer limitations into account at low concentrations. This study underlines the fact that K values cannot be interpreted without paying attention to the tested concentration level. Furthermore, it shows that the used MBBRs was able to handle high concentrations of pharmaceuticals, and that the most efficient removal occurs at concentrations above 100 µg L-1.

RevDate: 2020-09-11

Banerjee S, Ghosh D, Vishakha K, et al (2020)

Photodynamic Antimicrobial Chemotherapy (PACT) using riboflavin inhibits the mono and dual species biofilm produced by antibiotic resistant Staphylococcus aureus and Escherichia coli.

Photodiagnosis and photodynamic therapy pii:S1572-1000(20)30356-2 [Epub ahead of print].

PURPOSE: Multispecies biofilms play a significant role in persistent infections. Furthermore, by interspecies transfer of antibiotic resistance genes, multispecies biofilms spread antibiotic resistance. The purpose of this study was to investigate the effect of Photodynamic Antimicrobial Chemotherapy (PACT) using riboflavin on mono and multi species biofilms.

METHODS: For this we used two clinically relevant opportunistic pathogens species E. coli and S. aureus as mono-species and multispecies biofilms. We did broth dilution assay for antibacterial, crystal violet assay for biofilms and fluorometric study for reactive oxygen species (ROS) and extracellular polymeric substance (EPS) production by phenol-HCl method.

RESULTS: Antibacterial study revealed that photo-illuminated riboflavin shows bactericidal effect against each bacteria and their mix culture. E. coli was found to be little more resistant than S. aureus. Crystal violet assay revealed photo-illuminated riboflavin shows anti-biofilms activity against both mono and mix species biofilms. But mix species biofilms were more resistant to PACT than mono species biofilms. Further study revealed this may be due to the interaction between different EPS production, hence in mix species biofilms EPS production is less affected after PACT than mono species biofilms. We found photo-illuminated riboflavin increased the intracellular ROS production.

CONCLUSION: Photo-illuminated riboflavin shows bactericidal and anti-biofilms effect against each bacteria and their mix culture. Photo-illuminated increased intracellular ROS production, which may induce the oxidative stress and destroy the respiratory system of bacteria.

RevDate: 2020-09-11

Baidamshina DR, Koroleva VA, Trizna EY, et al (2020)

Anti-biofilm and wound-healing activity of chitosan-immobilized Ficin.

International journal of biological macromolecules pii:S0141-8130(20)34384-1 [Epub ahead of print].

Biofouling is among the key factors slowing down healing of acute and chronic wounds. Here we report both anti-biofilm and wound-healing properties of the chitosan-immobilized Ficin. The proposed chitosan-adsorption approach allowed preserving ~90% of the initial total activity of the enzyme (when using azocasein as a substrate) with stabilization factor of 4.9, and ~70% of its specific enzymatic activity. In vitro, the chitosan-immobilized Ficin degraded staphylococcal biofilms, this way increasing the efficacy of antimicrobials against biofilm-embedded bacteria. In vivo, in the presence of Ficin (either soluble or immobilized), the S. aureus-infected skin wound areas in rats reduced twofold after 4 instead of 6 days of treatment. Moreover, topical application of the immobilized enzyme resulted in a 3-log reduction of S. aureus cell count on the wound surfaces in 6 days, compared to more than 10 days required to achieve the same effect in control. Additional advantages include smoother reepithelisation, and new tissue formation exhibiting collagen structure characteristics closely reminiscent of those observed in the native tissue. Taken together, our data suggest that both soluble and immobilized Ficin appear beneficial for the treatment of biofilm-associated infections, as well as speeding up wound healing and microbial decontamination.

RevDate: 2020-09-11

Suer K, Ozkan L, M Guvenir (2020)

Antimicrobial effects of sodium hypochlorite and Er,Cr:YSGG laser against Enterococcus faecalis biofilm.

Nigerian journal of clinical practice, 23(9):1188-1193.

Aims: The aim of this study was to investigate the antimicrobial effect of Erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser with and without NaOCl solution. A total of 81 extracted human mandibular premolar teeth were used.

Materials and Methods: After root canal preparation and sterilization, the samples were inoculated with E. faecalis for 24 hours. The specimens were divided into 4 experimental groups. Group 1 (n = 25) was irradiated with 2 W laser, group 2 (n = 25) was irradiated with 0.75 W laser in combination with 2.5% NaOCl, group 3 (n = 25) was irrigated with 5% NaOCl and group 4 (n = 6) was not treated. Statistical analysis was performed by using Wilcoxon Signed Ranks, Mann-Whitney U and Kruskal-Wallis H tests.

Results: The combination of 0.75 W laser with 2.5% NaOCl regime was found to be just as effective at inhibiting the growth of E. faecalis and sterilization of all root canals as 5% NaOCl irrigation (P > 0.001). The 2 W laser had significant bactericidal effect in infected root canals however it did not eradicate all bacteria. The SEM observations were in accordance with the microbiologic findings.

Conclusions: Within the limitations of this laboratory study, NaOCl irrigation improved the antimicrobial effect of Er,Cr:YSGG laser irradiation. When the toxic effects of high percentage of NaOCl was considered, the combination of low-powered laser and low concentration of NaOCl can be used as an effective disinfection method in root canal treatment.

RevDate: 2020-09-10

Pérez J, Laureni M, van Loosdrecht MCM, et al (2020)

The role of the external mass transfer resistance in nitrite oxidizing bacteria repression in biofilm-based partial nitritation/anammox reactors.

Water research, 186:116348 pii:S0043-1354(20)30884-8 [Epub ahead of print].

A model-based study was developed to analyse the behaviour of Moving Bed Biofilm Reactor (MBBR) and Integrated Fixed-Film Activated Sludge (IFAS) reactor configurations for the removal of nitrogen in the main water line of municipal wastewater treatment plants via partial nitritation/anammox (PN/AMX). The basic principles and underlying mechanisms linking operating conditions to process performance were investigated, with particular focus on nitrite oxidizing bacteria (NOB) repression and resulting volumetric conversion rates. The external mass transfer resistance is a major factor differentiating granular sludge PN/AMX processes from MBBR or IFAS systems. The external mass transfer resistance was found to promote the metabolic coupling between anammox (AMX) and ammonia oxidizing bacteria (AOB), crucial for NOB repression in the biofilm. Operation at low bulk DO prevents NOB proliferation in the flocs of IFAS systems as AMX activity limits nitrite availability (the so-called AMX nitrite sink). Importantly, the effectiveness of the AMX nitrite sink strongly depends on the AMX sensitivity to oxygen. Also, over a broad range of operational conditions, the seeding of AOB from the biofilm played a crucial role in maintaining their activity in the flocs. From a practical perspective, while low DO promotes NOB repression, lower nitrogen loads have to be applied to maintain the same effluent quality. Thus, a trade-off between NOB repression and volumetric conversion capacity needs to be defined. To this end, IFAS allow for higher volumetric rates, but the window of operating conditions with effective NOB repression is smaller than that for MBBR. Ultimately, this study identified the principles controlling NOB in MBBR and IFAS systems and the key differences with granular reactors, allowing for the interpretation of (seemingly contradictory) published experimental results.

RevDate: 2020-09-10

Habashi N, Marom T, Steinberg D, et al (2020)

Biofilm distribution on tympanostomy tubes: An ex vivo descriptive study.

International journal of pediatric otorhinolaryngology, 138:110350 pii:S0165-5876(20)30493-6 [Epub ahead of print].

BACKGROUND: Tympanostomy tube (TT) insertion is a common procedure in children with otitis media with effusion. Post-TT otorrhea (PTTO) is a frequent post-operative complication. Biofilms are involved in chronic PTTO cases.

OBJECTIVE: To describe and qualitatively analyze the geometry and sites prone to biofilms on removed TTs, relatively to their position in the ear, past medical/surgical history and PTTO presence.

METHODS: Biofilms presence and topographic distribution on TTs were ex vivo evaluated by using scanning electron microscope, confocal microscope and stereo-microscope.

RESULTS: Forty-eight TTs from 30 children were analyzed. Indications for removal were: 71% due to retained TTs (average time from insertion: 24.4 ± 15.1 months), 23% due to chronic PTTO, and 6% due to TT obstruction/dysfunction. Different types of bacterial biofilms were detected on all TTs, regardless the time from their insertion nor their types. Biofilms were observed more on the perpendicular junction and on the internal lumen, and more biofilm colonies were detected on the medial part, facing the middle ear mucosa. TTs removed from children with PTTO exhibited more biofilm colonies when compared to their peers. Of the 16 children who underwent adenoidectomy concomitantly with TT insertion, 10 (62%) children were sent for TT removal due to retained TTs, and 6 (38%) children due to chronic PTTO (p = 0.03).

CONCLUSION: Descriptive analysis of biofilm topographic distribution demonstrated adhesions on specific TT areas: perpendicular junctions and the internal lumen. Such "prone zones" may be the future target areas for changes in TT geometry or can be specifically coated with anti-biofilm materials.

RevDate: 2020-09-10

Wang B, Lu L, Zhang Y, et al (2020)

Removal of bisphenol A by waste zero-valent iron regulating microbial community in sequencing batch biofilm reactor.

The Science of the total environment, 753:142073 pii:S0048-9697(20)35602-3 [Epub ahead of print].

The removal of bisphenol A (BPA) by waste zero-valent iron (ZVI) regulating microbial community in sequencing batch biofilm reactor (SBBR) was investigated. Compared with SBBR-BPA, the acclimation time of microorganisms in the presence of waste ZVI and BPA (SBBR-ZVI+BPA) decreased from 56 d to 49 d. During stable operation period, BPA was removed completely at 150th min and 100th min in the SBBR-BPA and SBBR-ZVI+BPA, respectively. The optimal initial pH and BPA concentration in the SBBRs were respectively 8.0 and 10 mg/L. The composition and content analysis of extracellular polymeric substances (EPS) using fluorescence spectrometer showed that the yield of EPS was enhanced by the addition of ZVI. The analysis of microbial community structure in the SBBRs using Illumina Miseq sequencing method indicated that the indexes of ACE, Chao1 and Shannon were higher and Simpson index was lower in the SBBR-ZVI+BPA. Moreover, the abundance of BPA biodegradation strains was increased in the presence of ZVI. This study provided a promising method with low cost of effectively removing BPA from wastewater.

RevDate: 2020-09-10

Lee CH, Chen YC, Chen IL, et al (2020)

Impact of biofilm production by Candida species and antifungal therapy on mortality of patients with candidemia.

Mycoses [Epub ahead of print].

BACKGROUND AND OBJECTIVES: Few studies have investigated the clinical outcomes of patients with candidemia caused by Candida species with different levels of biofilm formation. We aimed to investigate the impact of anti-fungal therapy on the outcome of candidemia caused by Candida species that were categorized as low biofilm formers (LBFs), moderate biofilm formers (MBFs), and high biofilm formers (HBFs).

METHODS: Adults with candidemia caused by LBF and HBF/MBF Candida species that were susceptible to fluconazole and caspofungin were included to investigate the impact of treatment with fluconazole versus an echinocandin on 30-day crude mortality.

RESULTS: In total, 215 patients with candidemia received fluconazole and 116 patients received an echinocandin. In multivariate analysis, Pittsburgh bacteremia score ≥ 4 (adjusted odds ratio [AOR] = 2.42; 95% confidence interval [CI], 1.32-4.41), malignancy (AOR = 3.45; 95% CI, 1.83-6.51), not removing the central venous catheter within 48 hours of a positive blood culture (AOR = 4.69; 95% CI, 2.61-8.45), and treatment with fluconazole for candidemia due to HBF/MBF Candida spp. (AOR = 2.23; 95% CI, 1.22-4.06) were independent factors associated with 30-day mortality. Of the 165 patients infected by HBF/MBF Candida isolates, those who received azole therapy had a significantly higher sepsis-related mortality rate than those who received echinocandin therapy (44.9% [49/109] vs. 26.8% [15/56], p = 0.03).

CONCLUSIONS: There was a trend of an independent association between fluconazole treatment and poor outcomes in the patients infected by HBF/MBF Candida strains.

RevDate: 2020-09-10

Forwood DL, Bryce EK, Caro E, et al (2020)

Influence of probiotics on biofilm formation and diversity of bacteria colonising crop sorghum ensiled with unsalable vegetables.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10877-5 [Epub ahead of print].

The objective of this study was to characterise in situ digestion kinetics and bacterial colonisation of crop sorghum ensiled with unsalable carrot or pumpkin at 0, 20 or 40% dry matter (DM). Silages with or without the application of a commercial probiotic were incubated in situ for 0, 3, 6, 9, 24 and 48 h. Calculation of in situ digestion kinetics was conducted for DM, organic matter and neutral detergent fibre (aNDF). The V4 region of the 16S rRNA gene was sequenced to determine the composition and diversity of bacteria colonising the silage. Organic matter and DM digestion kinetics indicated that greater vegetable inclusion increased (P < 0.05) the soluble fraction and effective degradability. Bacterial richness at 48 h incubation was greater (P = 0.02) in 20% carrot and 40% pumpkin treatments, compared with the control. An effect of level × probiotic was observed with increased Shannon diversity (P = 0.01) for 40% carrot and 20% pumpkin probiotic treatments, respectively. Primary colonising bacteria were members of the Prevotella genus, dominating after 3 and 6 h of incubation. The abundance of Prevotella increased by 4.1% at 3 h (P < 0.01) and by 4.7% at 9 h incubation with probiotics, compared with the control. Secondary biofilm colonisers included members of Treponema, Saccharofermentans, Fibrobacter, Ruminobacter and Anaerosporobacter genera, dominant from 9 h incubation onward. This study demonstrated that including unsalable vegetables at 20 or 40% DM increases the soluble fraction and effective degradability of sorghum silage during in situ digestion and increases diversity of bacteria colonising ensiled vegetables within the rumen. KEY POINTS: • Ensiling unsalable vegetables is a viable strategy to reduce food waste. • Ensiled vegetables increased in situ soluble fraction and effective degradability. • Bacterial richness at 48 h incubation improved with 20% carrot or 40% pumpkin. • Diversity of colonising rumen bacteria increased with carrot or pumpkin inclusion.

RevDate: 2020-09-10

Baldiris-Avila R, Montes-Robledo A, Y Buelvas-Montes (2020)

Phylogenetic Classification, Biofilm-Forming Capacity, Virulence Factors, and Antimicrobial Resistance in Uropathogenic Escherichia coli (UPEC).

Current microbiology pii:10.1007/s00284-020-02173-2 [Epub ahead of print].

Uropathogenic Escherichia coli (UPEC) is the main cause of urinary tract infections; in recent years, its importance as a pathogen has increased due to the emergence of hypervirulent and multiresistant strains. In this study, 190 urinary isolates of E. coli were assigned into the seven phylogenetic groups A (11.1%), B1 (4.7%), B2 (46.8%), C (5.8%) D (25.3%) F (2.6%), and Clade I (2.1%), and various virulence genes were examined with polymerase chain reaction methods. All isolates had at least one virulence factor of the 9 analyzed fyuA (81.1%), fimH (96.8%), iutA (74.7%), ompT (66.8%), kpsMTII (66.8%), traT (58.9%), PAI (43.6%), PapAH (26.3%), and usp (3.2%). The results showed a direct relationship between the virulence factors and phylogenetic group A and B2. Further, virulence genetic profiles fimH, fyuA, ompT, traT, and kpsMTII correlated with the production of strong biofilm, multidrug resistance, and the production of moderate hemolysin. These results suggest that these strains may become reservoirs of genes that encode virulence factors, which could be transferred horizontally enhancing their genomic background and high possibility of acquiring new genetic information for possible dissemination. This study provides the first description of phylogroups in UPEC in the Colombian Caribbean and the association with virulence factor profile, antimicrobial susceptibility, and their possible role in the epidemiology in Colombia.

RevDate: 2020-09-10

Socohou A, Sina H, Degbey C, et al (2020)

Antibiotics Resistance and Biofilm Formation Capacity of Staphylococcus spp. Strains Isolated from Surfaces and Medicotechnical Materials.

International journal of microbiology, 2020:6512106.

Staphylococcus spp. is most often implicated in nosocomial infections. The objective of this study is to evaluate the susceptibility to antibiotics and the biofilm formation capacity of staphylococci species isolated from surfaces and medicotechnical materials at the university hospital center of Abomey-Calavi/Sô-Ava in Benin. Samples were collected according to ISO/DIS14698-1 standard from the surfaces and medicotechnical materials by the dry swab method. The isolation of Staphylococcus strains was performed on Chapman agar, and their identification was performed using microscopic and biochemical methods. The susceptibility of Staphylococcus isolates to antibiotics was evaluated by the disc diffusion method according to EUCAST and CLSI recommendations. The biofilm formation was qualitatively assessed using microplates. Of the 128 surfaces and medicotechnical material samples analyzed, 77% were contaminated with Staphylococcus spp. Thirteen species of Staphylococcus were isolated in different proportions but the pediatric department was the most contaminated (33%) by S. aureus. Resistance to antibiotics considerably varies according to the species of Staphylococcus. However, antibiotics such as chloramphenicol and vancomycin are the most effective on S. aureus, whereas coagulase-negative staphylococci developed less resistance to gentamycin and ciprofloxacin. The biofilm test reveals that 37% of our isolated strains were biofilm formers. Although regular monitoring of hospital hygiene is crucial, the optimal use of antibiotics is a cornerstone of reducing antimicrobial resistance.

RevDate: 2020-09-10

Abebe GM (2020)

The Role of Bacterial Biofilm in Antibiotic Resistance and Food Contamination.

International journal of microbiology, 2020:1705814.

Biofilm is a microbial association or community attached to different biotic or abiotic surfaces or environments. These surface-attached microbial communities can be found in food, medical, industrial, and natural environments. Biofilm is a critical problem in the medical sector since it is formed on medical implants within human tissue and involved in a multitude of serious chronic infections. Food and food processing surface become an ideal environment for biofilm formation where there are sufficient nutrients for microbial growth and attachment. Therefore, biofilm formation on these surfaces, especially on food processing surface becomes a challenge in food safety and human health. Microorganisms within a biofilm are encased within a matrix of extracellular polymeric substances that can act as a barrier and recalcitrant for different hostile conditions such as sanitizers, antibiotics, and other hygienic conditions. Generally, they persist and exist in food processing environments where they become a source of cross-contamination and foodborne diseases. The other critical issue with biofilm formation is their antibiotic resistance which makes medication difficult, and they use different physical, physiological, and gene-related factors to develop their resistance mechanisms. In order to mitigate their production and develop controlling methods, it is better to understand growth requirements and mechanisms. Therefore, the aim of this review article is to provide an overview of the role of bacterial biofilms in antibiotic resistance and food contamination and emphasizes ways for controlling its production.

RevDate: 2020-09-10

Trizna EY, Yarullina MN, Baidamshina DR, et al (2020)

Bidirectional alterations in antibiotics susceptibility in Staphylococcus aureus-Pseudomonas aeruginosa dual-species biofilm.

Scientific reports, 10(1):14849 pii:10.1038/s41598-020-71834-w.

In mixed infections, the bacterial susceptibility differs significantly compared to monocultures of bacteria, and generally the concentrations of antibiotics required for the treatment increases drastically. For S. aureus and P. aeruginosa dual species biofilms, it has been numerously reported that P. aeruginosa decreases S. aureus susceptibility to a broad range of antibiotics, including beta-lactams, glycopeptides, aminoglycosides, macrolides, while sensitizes to quinolones via secretion of various metabolites. Here we show that S. aureus also modulates the susceptibility of P. aeruginosa to antibiotics in mixed cultures. Thus, S. aureus-P. aeruginosa consortium was characterized by tenfold increase in susceptibility to ciprofloxacin and aminoglycosides compared to monocultures. The same effect could be also achieved by the addition of cell-free culture of S. aureus to P. aeruginosa biofilm. Moreover, similar increase in antibiotics efficacy could be observed following addition of S. aureus suspension to the P. aeruginosa mature biofilm, compared to P. aeruginosa monoculture, and vice versa. These findings open promising perspectives to increase the antimicrobial treatment efficacy of the wounds infected with nosocomial pathogens by the transplantation of the skin residential microflora.

RevDate: 2020-09-10

Mao B, Xie Y, Yang H, et al (2020)

Casein phosphopeptide-amorphous calcium phosphate modified glass ionomer cement attenuates demineralization and modulates biofilm composition in dental caries.

Dental materials journal [Epub ahead of print].

The study investigated the effects of the modified conventional glass ionomer cement (GIC) incorporated with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on biofilm composition of dental caries. Shear bond strength, durability tests, adhesive remnant index (ARI) and scanning electron microscope were used to measure the physical properties. Microhardness and ions release were determined to evaluate anti-demineralization effects; growth of the biofilm and its composition were assessed using MTT assay and Q-PCR assay. All experimental groups exhibited a significant stimulation of ions release, and reduced attenuation of microhardness. Nearly 39% reduction in the bacterial biofilm was observed with 5% CPP-ACP group. The regulation ability is mainly manifested in the inhibition of S. mutans and promotion of S. gordonii. The modified GICs by exhibiting anti-demineralization effects potentially lead to a reduction in the cariogenicity of plaque and can serve as a putative promising remineralization system with both enhanced antimicrobial and remineralization properties.

RevDate: 2020-09-10

Racenis K, Kroica J, Rezevska D, et al (2020)

S. aureus Colonization, Biofilm Production, and Phage Susceptibility in Peritoneal Dialysis Patients.

Antibiotics (Basel, Switzerland), 9(9): pii:antibiotics9090582.

Peritonitis caused by Staphylococcusaureus is of major importance in peritoneal dialysis (PD) patients due to its great virulence profile and biofilm formation ability. Bacteriophages are a potential tool to treat peritonitis resulting from biofilm-associated infections. We screened S. aureus colonization in 71 PD patients from the nasal cavity, groin, and PD exit-site regions and analyzed clinical outcomes in these patients. We performed biofilm-formation testing of different strains and compared the isolates of one patient to detect phenotypic differences in S. aureus. Phage cocktails were used to detect S. aureus in vitro susceptibility. An adaptation procedure was performed in cases of bacterial resistance. Around 30% of PD patients (n = 21) were found to be S. aureus carriers; from these, a total of 34 S. aureus strains were isolated, of which 61.8% (n = 21) produced a strong biofilm. Phenotypic differences in strain biofilm production were detected in eight patients out of ten. All strains were sensitive to commonly used antibiotics. Broadly positive phage lytic activity (100%) was observed in six cocktails out of seven, and bacterial resistance towards phages was overcome using adaptation. Overall phages showed a promising in vitro effect in biofilm-forming S. aureus strains.

RevDate: 2020-09-09

Hill C, Pan M, Babrak L, et al (2015)

Presence of Virulence-Associated Genes and Ability to Form Biofilm among Clinical Isolates of Escherichia coli Causing Urinary Infection in Domestic Animals.

Advances in microbiology, 5(8):573-579.

Background: Urinary tract infection caused by Escherichia coli is a frequently observed condition both in humans and animals. Uropathogenic E. coli (UPEC) has been shown to have a pathogenicity island that enables them to infect the urinary tract. Because there is little information about the presence of UPEC-associated virulent genes in animal isolates this work was carried out with the intent to enhance the understanding about the strains of E.coli that cause infections in animals.

Results: We screened 21 E. coli strains isolated causing urinary tract infection in domestic animals. Primers were designed to amplify urinary infection-associated genes. Nine genes, papA, tcpC, fyuA, tpbA, Lma, hylA, picU, tonB, and flicC were then amplified and sequenced. Different from the human isolate CFT073, all the animals E. coli lack some of the pathogenesis-associated genes. Genes encoding for proteins used to scavenge iron appear not to be so necessary during animal infections as they are in human infection. In further investigation of phenotypic properties, it was observed that animal UPECs have significantly more impaired ability to form biofilms than human UPEC strain.

Conclusions: This study identified significant differences between human and animal UPECs. This may have its roots in the fact that it is difficult to determine if an animal has symptoms. Future studies will focus on some of the observations.

RevDate: 2020-09-09

Montenegro LAS, Silva E Farias IP, de Araújo EC, et al (2020)

Biochemical and microbiological analysis of the saliva of institutionalized elderly: With edentulism, use of dentures and presence of biofilm.

Journal of clinical and experimental dentistry, 12(7):e632-e637 pii:56842.

Background: To analyze biochemical and microbiological parameters of the saliva of institutionalized elders and to investigate the relation of these parameters with edentulism, use of dentures and presence of biofilm.

Material and Methods: A cross-sectional study carried was out in seven long-term institutions. Samples (n=161) of unstimulated saliva were collected for analysis of salivary flow, quantification of total proteins and identification of microorganisms. Oral examination was carried out to verify the number of missing teeth, the use of dentures and the presence of visible biofilm on the surface of teeth and dentures. Associations were performed using chi-square or Fisher's exact test (α<0.05). Mann-Whitney Test was used to identify differences in the salivary flow and total proteins (α<0.05).

Results: There was no association between the type of edentulism and use of dentures with biochemical and microbiological parameters of saliva (p>0.05). Associations were observed between the presence of dentures biofilm and the colonization of Streptococcus sp. (p=0.038) and Candida sp. (p=0.03).

Conclusions: The absence of teeth and use of dentures do not influence the amount of total proteins and the microorganisms count in saliva. Denture biofilms are associated with the presence of Streptococcus sp. and Candida sp. in saliva of institutionalized elders. Key words:Candida, long-stay institutions for elders, saliva, Streptococcus, Staphylococcus.

RevDate: 2020-09-09

Kumari P, Nath Y, Murty US, et al (2020)

Sortase A Mediated Bioconjugation of Common Epitopes Decreases Biofilm Formation in Staphylococcus aureus.

Frontiers in microbiology, 11:1702.

Staphylococcus aureus is one of the most notorious pathogens and is frequently associated with nosocomial infections imposing serious risk to immune-compromised patients. This is in part due to its ability to colonize at the surface of indwelling medical devices and biofilm formation. Combating the biofilm formation with antibiotics has its own challenges like higher values of minimum inhibitory concentrations. Here, we describe a new approach to target biofilm formation by Gram positive bacteria. Sortase A is a transpeptidase enzyme which is responsible for tagging of around ∼22 cell surface proteins onto the outer surface. These proteins play a major role in the bacterial virulence. Sortase A recognizes its substrate through LPXTG motif. Here, we use this approach to install the synthetic peptide substrates onS. aureus. Sortase A substrate mimic, 6His-LPETG peptide was synthesized using solid phase peptide chemistry. Incorporation of the peptide on the cell surface was measured using ELISA. Effect of peptide incubation on Staphylococcus aureus biofilm was also studied. 71.1% biofilm inhibition was observed with 100 μM peptide while on silicon coated rubber latex catheter, 45.82% inhibition was observed. The present work demonstrates the inability of surface modified S. aureus to establish biofilm formation thereby presenting a novel method for attenuating its virulence.

RevDate: 2020-09-09

Di Lodovico S, Menghini L, Ferrante C, et al (2020)

Hop Extract: An Efficacious Antimicrobial and Anti-biofilm Agent Against Multidrug-Resistant Staphylococci Strains and Cutibacterium acnes.

Frontiers in microbiology, 11:1852.

Bacteria belonging to Staphylococcus genus, in particular methicillin-resistant Staphylococcus aureus and multidrug-resistant Staphylococcus epidermidis, together with Cutibacterium acnes are the main strains involved in skin disease. The increase in multidrug-resistant bacteria has revived attention on natural compounds as alternative agents for the treatment management. Among these, hop extract, a hydroalcoholic solution obtained from experimental crops of Humulus lupulus L. variety cascade (hop), displays diverse biological properties including an antimicrobial one. The aim of this study was to evaluate the antimicrobial activity and the capacity to inhibit the biofilm formation of a characterized hop extract against S. aureus and S. epidermidis multidrug-resistant strains and against a C. acnes strain. The hop extract was characterized by (i) phytochemical analysis through a reversed-phase high-performance liquid chromatography (HPLC)-fluorimetric method, (ii) biocompatibility test with Artemia salina L., (iii) cytotoxicity against two cell lines, (iv) docking analysis, and (v) antimicrobial and antibiofilm activities by detection of zones inhibition, minimal inhibitory concentrations (MICs), biomass quantification, and cell viability. The hop extract was biocompatible and non-cytotoxic at all tested concentrations. HPLC analysis revealed significant levels of gallic acid, resveratrol, and rutin. This last compound was the most representative displaying a high affinity against PBP2a and KAS III (Ki values in the submicromolar range). The characterized hop extract showed a good antimicrobial action with MICs ranging from 1 to 16 μg/mL and was able to inhibit the biofilm formation of all tested strains, except for two S. aureus strains. The biofilm formed in presence of the hop extract was significantly reduced in most cases, even when present at a concentration of 1/4 MIC. The live/dead images showed a remarkable inhibition in the biofilm formation by hop extract with a weak killing action. Overall, the tested hop extract is a good candidate to further explore for its use in the prevention of infection particularly, by multidrug-resistant Gram-positive pathogens.

RevDate: 2020-09-09

Yu H, Xiong J, Qiu J, et al (2020)

Type III Secretion Protein, PcrV, Impairs Pseudomonas aeruginosa Biofilm Formation by Increasing M1 Macrophage-Mediated Anti-bacterial Activities.

Frontiers in microbiology, 11:1971.

Pseudomonas aeruginosa biofilms employ a variety of strategies to hijack the host immune defense system to achieve chronic infection. However, the bacterial components that are involved in this process are not yet fully understood. PcrV, a needle tip protein of the P. aeruginosa type III secretion system (T3SS), was downregulated during P. aeruginosa biofilm infection. The impaired expression of the P. aeruginosa pcrV gene is associated with attenuated immune activation and an increased percentage of M2 macrophages following P. aeruginosa biofilm infection. Treatment with exogenous PcrV produced from Escherichia coli elevated tissue inflammation and the percentage of M1 macrophages, resulting in reduction in the biofilm burden. Further analyses demonstrated that the potential of PcrV to induce classically activated M1 macrophages as evidenced by the increased production of proinflammatory cytokines and anti-bacterial mediators, including inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS), as well as increased phagocytosis of bacteria. Mechanistically, PcrV-mediated promotion of macrophage M1 polarization and phagocytosis occurs through the activation of mitogen-activated protein kinases (MAPKs) and NF-κB signaling pathways. Collectively, these findings reveal a potential role of PcrV in skewing host immune defense to promote P. aeruginosa biofilm infection and provide new insights into the therapeutic strategies for P. aeruginosa biofilm infection.

RevDate: 2020-09-09

Begić M, D Josić (2020)

Biofilm formation and extracellular microvesicles - the way of foodborne pathogens toward resistance.

Electrophoresis [Epub ahead of print].

Almost all known food borne pathogens are able to form biofilms as one of the strategies for survival under harsh living conditions, to ward off the inhibition and the disinfection during food production, transport and storage, as well as during cleaning and sanitation of corresponding facilities. Biofilms are communities where microbial cells live under constant intracellular interaction and communication. Members of the biofilm community are embedded into extracellular matrix that contains polysaccharides, DNA, lipids, proteins and small molecules that protect microorganisms and enable their intercellular communication under stress conditions. Membrane vesicles (MVs) are produced by both Gram positive and Gram negative bacteria. These lipid membrane-enveloped nanoparticles play an important role in biofilm genesis and in communication between different biofilm members. Furthermore, MVs are involved in other important steps of bacterial life like cell wall modeling, cellular division and intercellular communication. They also carry toxins and virulence factors, as well as nucleic acids and different metabolites, and play a key role in host infections. After entering host cells, MVs can start many pathologic processes and cause serious harm and cell death. Prevention and inhibition of both biofilm formation and shedding of MVs by food borne pathogens has a very important role in food production, storage and food safety in general. Better knowledge of biofilm formation and maintaining, as well as the role of microbial vesicles in this process and in the process of host cells' infection is essential for food safety and prevention of both food-spoilage and host infection. This article is protected by copyright. All rights reserved.

RevDate: 2020-09-09

Sadid-Zadeh R, Willis J, Forgo G, et al (2020)

Comparative Analysis of Biofilm Formation on Materials Used for the Fabrication of Implant-Supported Prostheses.

Brazilian dental journal, 31(4):380-384 pii:S0103-64402020000400380.

The purpose of this study was to compare biofilm formation on materials used for the fabrication of implant-supported dental prostheses. Twenty discs (D=15 mm, H=3 mm) were fabricated from one of the following restorative materials: yttria tetragonal zirconia polycrystal (Y-TZP); commercially pure titanium (CP-Ti); or heat-cured polymethyl methacrylate (PMMA). Specimens were polished following standard protocols. A non-contact profilometer (NPFLEX, Bruker, UK) was used to assess the surface roughness of each disk; results were reported as Ra (µm). Five strains of Gram-negative bacteria frequently associated with peri-implantitis, Aggregatibacter actinomycetemcomitans, Candida. albicans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia, were cultured on hand-polished discs fabricated from heat-cured PMMA, Y-TZP, or CP-Ti to compare biofilm formation on each type of material. The results were reported as colony-forming units per milliliter (CFU/mL). One-way ANOVA and post hoc tests were used to compare surface roughness and bacterial colonization on the respective materials. Statistical significance was set at a = 0.05. Discs fabricated from Y-TZP had a significantly higher Ra value (350 ± 30 µm) than either PMMA, or CP-Ti discs. Discs fabricated from either Y-TZP and CP-Ti may exhibit less colonization by bacteria associated with peri-mucositis and peri-implantitis. Y-TZP and CP-Ti are suggested materials for fabrication of implant-supported prostheses, considering biofilm formation.

RevDate: 2020-09-09

Rizzo NN, Pottker ES, Webber B, et al (2020)

Effect of two lytic bacteriophages against multidrug-resistant and biofilm-forming Salmonella Gallinarum from poultry.

British poultry science [Epub ahead of print].

SALMONELLA GALLINARUM: (SG) infections cause fowl typhoid, which leads to important economic losses. Multidrug resistance (MDR) and the capacity for bacteria to form biofilms could play an important role in the persistence of SG in poultry flocks resulting in intermittent disease outbreaks. The aim of the following study was to assess the lytic activity of two new bacteriophages (salmonella phages UPF_BP1 and UPF_BP2) against MDR and biofilm-forming SG. Forty-six strains of SG, isolated in 2015, were characterised by antimicrobial resistance, biofilm formation profiles and susceptibility to two new bacteriophages. Of these strains, 24% were multidrug resistant and more than 80% formed biofilm, with no statistical difference between incubation temperatures (42°C or 22°C). With regard to the lytic activity of the phages, 85% of strains were susceptible to at least one phage. while 87% were lysed by both phages, including MDR and biofilm producing strains. The use of salmonella phages UPF_BP1 and UPF_BP2 were shown to be promising alternatives for the biological control of fowl typhoid.

RevDate: 2020-09-09

Seviour T, Wong LL, Lu Y, et al (2020)

Phase Transitions by an Abundant Protein in the Anammox Extracellular Matrix Mediate Cell-to-Cell Aggregation and Biofilm Formation.

mBio, 11(5): pii:mBio.02052-20.

This study describes the first direct functional assignment of a highly abundant extracellular protein from a key environmental and biotechnological biofilm performing an anaerobic ammonium oxidation (anammox) process. Expression levels of Brosi_A1236, belonging to a class of proteins previously suggested to be cell surface associated, were in the top one percentile of all genes in the "Candidatus Brocadia sinica"-enriched biofilm. The Brosi_A1236 structure was computationally predicted to consist of immunoglobulin-like anti-parallel β-strands, and circular dichroism conducted on the isolated surface protein indicated that β-strands are the dominant higher-order structure. The isolated protein was stained positively by the β-sheet-specific stain thioflavin T, along with cell surface- and matrix-associated regions of the biofilm. The surface protein has a large unstructured content, including two highly disordered domains at its C terminus. The disordered domains bound to the substratum and thereby facilitated the adhesion of negatively charged latex microspheres, which were used as a proxy for cells. The disordered domains and isolated whole surface protein also underwent liquid-liquid phase separation to form liquid droplets in suspension. Liquid droplets of disordered protein wet the surfaces of microspheres and bacterial cells and facilitated their coalescence. Furthermore, the surface layer protein formed gels as well as ordered crystalline structures. These observations suggest that biophysical remodeling through phase transitions promotes aggregation and biofilm formation.IMPORTANCE By employing biophysical and liquid-liquid phase separation concepts, this study revealed how a highly abundant extracellular protein enhances the key environmental and industrial bioprocess of anaerobic ammonium oxidation (anammox). Extracellular proteins of environmental biofilms are understudied and poorly annotated in public databases. Understanding the function of extracellular proteins is also increasingly important for improving bioprocesses and resource recovery. Here, protein functions were assessed based on theoretical predictions of intrinsically disordered domains, known to promote adhesion and liquid-liquid phase separation, and available surface layer protein properties. A model is thus proposed to explain how the protein promotes aggregation and biofilm formation by extracellular matrix remodeling and phase transitions. This work provides a strong foundation for functional investigations of extracellular proteins involved in biofilm development.

RevDate: 2020-09-09

Bosch ME, Bertrand BP, Heim CE, et al (2020)

Staphylococcus aureus ATP Synthase Promotes Biofilm Persistence by Influencing Innate Immunity.

mBio, 11(5): pii:mBio.01581-20.

Staphylococcus aureus is a major cause of prosthetic joint infection (PJI), which is characterized by biofilm formation. S. aureus biofilm skews the host immune response toward an anti-inflammatory profile by the increased recruitment of myeloid-derived suppressor cells (MDSCs) that attenuate macrophage proinflammatory activity, leading to chronic infection. A screen of the Nebraska Transposon Mutant Library identified several hits in the ATP synthase operon that elicited a heightened inflammatory response in macrophages and MDSCs, including atpA, which encodes the alpha subunit of ATP synthase. An atpA transposon mutant (ΔatpA) had altered growth kinetics under both planktonic and biofilm conditions, along with a diffuse biofilm architecture that was permissive for leukocyte infiltration, as observed by confocal laser scanning microscopy. Coculture of MDSCs and macrophages with ΔatpA biofilm elicited significant increases in the proinflammatory cytokines interleukin 12p70 (IL-12p70), tumor necrosis factor alpha (TNF-α), and IL-6. This was attributed to increased leukocyte survival resulting from less toxin and protease production by ΔatpA biofilm as determined by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The enhanced inflammatory response elicited by ΔatpA biofilm was cell lysis-dependent since it was negated by polyanethole sodium sulfanate treatment or deletion of the major autolysin, Atl. In a mouse model of PJI, ΔatpA-infected mice had decreased MDSCs concomitant with increased monocyte/macrophage infiltrates and proinflammatory cytokine production, which resulted in biofilm clearance. These studies identify S. aureus ATP synthase as an important factor in influencing the immune response during biofilm-associated infection and bacterial persistence.IMPORTANCE Medical device-associated biofilm infections are a therapeutic challenge based on their antibiotic tolerance and ability to evade immune-mediated clearance. The virulence determinants responsible for bacterial biofilm to induce a maladaptive immune response remain largely unknown. This study identified a critical role for S. aureus ATP synthase in influencing the host immune response to biofilm infection. An S. aureus ATP synthase alpha subunit mutant (ΔatpA) elicited heightened proinflammatory cytokine production by leukocytes in vitro and in vivo, which coincided with improved biofilm clearance in a mouse model of prosthetic joint infection. The ability of S. aureus ΔatpA to augment host proinflammatory responses was cell lysis-dependent, as inhibition of bacterial lysis by polyanethole sodium sulfanate or a ΔatpAΔatl biofilm did not elicit heightened cytokine production. These studies reveal a critical role for AtpA in shaping the host immune response to S. aureus biofilm.

RevDate: 2020-09-08

Yi L, Jin M, Li J, et al (2020)

Antibiotic resistance related to biofilm formation in Streptococcus suis.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10873-9 [Epub ahead of print].

Streptococcus suis (S. suis) is an important zoonotic agent, which seriously impacts the pig industry and human health in various countries. Biofilm formation is likely contributing to the virulence and drug resistance in S. suis. A better knowledge of biofilm formation as well as to biofilm-dependent drug resistance mechanisms in S. suis can be of great significance for the prevention and treatment of S. suis infections. This literature review updates the latest scientific data related to biofilm formation in S. suis and its impact on drug tolerance and resistance.Key points• Biofilm formation is the important reasons for drug resistance of SS infections.• The review includes the regulatory mechanism of SS biofilm formation.• The review includes the drug resistance mechanisms of SS biofilm.

RevDate: 2020-09-08

Li X, Tsui KH, Tsoi JKH, et al (2020)

A nanostructured anti-biofilm surface widens the efficacy against spindle-shaped and chain-forming rod-like bacteria.

Nanoscale [Epub ahead of print].

Current control of pathogenic bacteria at all biomaterial interfaces is poorly attuned to a broad range of disease-causing pathogens. Leading antimicrobial surface functionalization strategies with antimicrobial peptides (AMPs), defensins, have not shown their promised efficacy. One of the main problems is the lack of stability and swift clearance from the surface. Surface nanotopography bearing sharp protrusions is a non-chemical solution that is intrinsically stable and long-lasting. Previously, the geometrically ordered arrays of nanotipped spines repelled or rapidly ruptured bacteria that come into contact. The killing properties so far work on cocci and rod-like bacteria, but there is no validation of the efficacy of protrusional surfaces on pathogenic bacteria with different sizes and morphologies, thus broadening the utility of such surfaces to cover increasingly more disease entities. Here, we report a synthetic analogue of nanotipped spines with a pyramidal shape that show great effectiveness on species of bacteria with strongly contrasting shapes and sizes. To highlight this phenomenon in the field of dental applications where selective bacterial control is vital to the clinical success of biomaterial functions, we modified the poly(methyl)-methacrylate (PMMA) texture and tested it against Streptococcus mutans, Enterococcus faecalis, Porphyromonas gingivalis, and Fusobacterium nucleatum. These nanopyramids performed effectively at levels well above those of normal and roughened PMMA biomaterials for dentistry and a model material for general use in medicine and disease transmission in hospital environments.

RevDate: 2020-09-08

Dong J, Wang B, Xiang B, et al (2020)

Research on the effect of TiO2 nanotubes coated by gallium nitrate on Staphylococcus aureus-Escherichia coli biofilm formation.

Journal of clinical laboratory analysis [Epub ahead of print].

BACKGROUND: In clinical practice, the cases with bacterial infection caused by titanium implants and bacterial biofilm formation on the surface of titanium materials implanted into human body can often be observed. Thus, this study aimed to demonstrate whether the mixed biofilm of Staphylococcus aureus/Escherichia coli can be formed on the surface of titanium material through in vitro experiments and its formation rules.

METHODS: The titanium plates were put into the well containing S aureus or/and E coli. Bacterial adhesion and biofilm formation were analyzed by crystal violet, XTT method, confocal laser scanning microscopy, and scanning electron microscopy.

RESULTS: The results of bacterial adhesion in each group at 6-72 hours showed that the number of bacterial adhesion in each group was increased with the extension of time and reached to the highest level at 72 hours. Moreover, the biofilm structure in the S aureus-E coli group was significantly more complex than that of the simple S aureus group or E coli group, and the number of bacteria was also significantly increased in the S aureus-E coli group.

CONCLUSION: Those data provide a laboratory basis for the prevention and treatment of mixed infection of subsequent biological materials.

RevDate: 2020-09-08

Silvestre I, Borrego MJ, L Jordão (2020)

Biofilm formation by ST17 and ST19 strains of Streptococcus agalactiae.

Research in microbiology pii:S0923-2508(20)30080-2 [Epub ahead of print].

Bacterial biofilms are an important virulence factor with a vital role in evasion from the host immune system, colonization and infection. The aim of the present study was to evaluate in vitro the effects of three environmental factors (H+, glucose and human plasma) in biofilm formation, by carrier and invasive S. agalactiae strains of ST17 and ST19 sequence types, including DNase producers and non-producers. Bacteria ability to assemble biofilms was classified based on crystal violet assay. Biofilm formation was also monitored by scanning electron microscopy. Depending on the growth medium used, each bacterial isolate could fit in different biofilm production categories. Our data showed that optimal conditions for S. agalactiae biofilm assembly were reached after 48 h incubation at pH 7.6 in the presence of glucose and inactivated human plasma. In the presence of inactivated human plasma, the biofilm biomass of ST19 strains experienced a higher increase than ST17 strains. The composition of the extracellular polymeric matrix of the three strongest biofilm producers (all from ST17) was accessed by enzymatic digestion of mature biofilms and proteins were shown to be the predominant component. The detailed identification of the extracellular protein components should contribute to the development of new therapeutic strategies to fight S. agalactiae infections.

RevDate: 2020-09-07

Costa RC, Souza JGS, Bertolini M, et al (2020)

Extracellular biofilm matrix leads to microbial dysbiosis and reduces biofilm susceptibility to antimicrobials on titanium biomaterial: An in vitro and in situ study.

Clinical oral implants research [Epub ahead of print].

OBJECTIVES: To test the role of exopolysaccharide (EPS) polymers on the composition/virulence of biofilm formed on titanium (Ti) surfaces, the effect on antibiotic susceptibility, and whether a dual-targeting therapy approach for disrupted EPS matrix could improve the antimicrobial effect.

MATERIALS AND METHODS: A microcosm biofilm model using human saliva as inoculum was used and the microbial composition was assessed by Checkerboard DNA-DNA hybridization. EPS-enriched biofilms virulence was tested using fibroblast monolayer. Povidone iodine (PI) was used as EPS-targeting agent followed by amoxicillin+metronidazole antibiotic to reduce bacterial biomass using an in situ model.

RESULTS: An EPS-enriched environment, obtained by sucrose exposure, promoted bacterial accumulation and led to a dysbiosis on biofilms, favoring the growth of Streptococcus, Fusobacterium and Campylobacter species and even strict anaerobic species related to peri-implant infections, such as Porphyromonas gingivalis and Tannerella forsythia (~3-fold increase). EPS-enriched biofilm transitioned from a commensal aerobic to a pathogenic anaerobic profile. EPS increased biofilm virulence promoting higher host cell damage and reduced antimicrobial susceptibility, but the use of a dual-targeting approach with PI pre-treatment disrupted EPS matrix scaffold, increasing antibiotic effect on in situ biofilms.

CONCLUSION: Altogether, our data provide new insights of how EPS-matrix creates an environment that favors putative pathogens growth and shed light to a promising approach that uses matrix disruption as initial step to potentially improve implant-related infections treatment.

RevDate: 2020-09-07

Jeffries J, Thongsomboon W, Visser JA, et al (2020)

Variation in the ratio of curli and phosphoethanolamine cellulose associated with biofilm architecture and properties.

Biopolymers [Epub ahead of print].

Bacterial biofilms are communities of bacteria entangled in a self-produced extracellular matrix (ECM). Escherichia coli direct the assembly of two insoluble biopolymers, curli amyloid fibers, and phosphoethanolamine (pEtN) cellulose, to build remarkable biofilm architectures. Intense curiosity surrounds how bacteria harness these amyloid-polysaccharide composites to build biofilms, and how these biopolymers function to benefit bacterial communities. Defining ECM composition involving insoluble polymeric assemblies poses unique challenges to analysis and, thus, to comparing strains with quantitative ECM molecular correlates. In this work, we present results from a sum-of-the-parts 13 C solid-state nuclear magnetic resonance (NMR) analysis to define the curli-to-pEtN cellulose ratio in the isolated ECM of the E. coli laboratory K12 strain, AR3110. We compare and contrast the compositional analysis and comprehensive biofilm phenotypes for AR3110 and a well-studied clinical isolate, UTI89. The ECM isolated from AR3110 contains approximately twice the amount of pEtN cellulose relative to curli content as UTI89, revealing plasticity in matrix assembly principles among strains. The two parent strains and a panel of relevant gene mutants were investigated in three biofilm models, examining: (a) macrocolonies on agar, (b) pellicles at the liquid-air interface, and (c) biomass accumulation on plastic. We describe the influence of curli, cellulose, and the pEtN modification on biofilm phenotypes with power in the direct comparison of these strains. The results suggest that curli more strongly influence adhesion, while pEtN cellulose drives cohesion. Their individual and combined influence depends on both the biofilm modality (agar, pellicle, or plastic-associated) and the strain itself.

RevDate: 2020-09-07

Sandala J, JS Gunn (2021)

In Vitro Evaluation of Anti-biofilm Agents Against Salmonella enterica.

Methods in molecular biology (Clifton, N.J.), 2182:127-139.

Salmonella enterica is able to establish robust adherent communities called biofilms that allow for long-term colonization of both biotic and abiotic surfaces. These biofilm communities pose a significant challenge to successful eradication of the bacteria from contaminated surfaces and the infected host, as entry into the biofilm phenotype confers the bacterial population with tolerance to a variety of environmental and therapeutic insults to which it would otherwise be susceptible. The identification of antimicrobial strategies that specifically target the Salmonella biofilm state is therefore of great importance in order to both prevent and treat biofilm-mediated disease. Here, we provide detailed methods for the in vitro cultivation of Salmonella biofilms that can easily be scaled up for use in high-throughput screening of candidate anti-biofilm agents. These assays may also be utilized to further characterize the inhibitory and/or disruptive capabilities of lead anti-biofilm agents, as well as to identify combination treatments that demonstrate enhanced anti-biofilm effects. Furthermore, the assays may be slightly modified (e.g., optimal growth conditions) to evaluate other bacterial genera.

RevDate: 2020-09-07

Yu L, Wang H, Han X, et al (2020)

The two-component system, BasSR, is involved in the regulation of biofilm and virulence in avian pathogenic Escherichia coli.

Avian pathology : journal of the W.V.P.A [Epub ahead of print].

Avian pathogenic Escherichia coli (APEC) is a subgroup of extra-intestinal pathogenic E. coli (ExPEC) strains that cause avian colibacillosis, resulting in significant economic losses to the poultry industry worldwide. It has been reported that a few two-component signal transduction systems (TCS) participate in the regulation of the virulence factors of APEC infection. In this study, a basSR-deficient mutant strain was constructed from its parent strain APECX40 (WT), and high-throughput sequencing was performed to analyse the transcriptional profile of WT and its mutant strain XY1. Results showed that the deletion of basSR down-regulated the transcript levels of a series of biofilm- and virulence-related genes. Results of biofilm formation assays and animal model experiments indicated that the deletion of basSR inhibited biofilm formation in vitro and decreased bacterial virulence and colonisation in vivo. In addition, electrophoretic mobility shift assays confirmed that the BasR protein could bind to the promoter regions of several biofilm- and virulence-related genes, including ais, opgC and fepA. This study suggests that the BasSR TCS might be a global regulator in the pathogenesis of APEC infection. RESEARCH HIGHLIGHTS Transcriptional profiling showed that BasSR might be a global regulator in APEC. BasSR increases APEC pathogenicity in vivo. BasSR positively regulates biofilm- and the virulence-associated genes. BasSR can bind to the promoter regions of virulence-associated genes ais, opgC and fepA.

RevDate: 2020-09-07

Pan M, Lu C, Zheng M, et al (2020)

Unnatural Amino-Acid-Based Star-Shaped Poly(l-Ornithine)s as Emerging Long-Term and Biofilm-Disrupting Antimicrobial Peptides to Treat Pseudomonas aeruginosa-Infected Burn Wounds.

Advanced healthcare materials [Epub ahead of print].

Peptide-based antimicrobial materials are recognized as promising alternatives to antibiotics to circumvent the emergence of antibiotic-resistant bacteria or to combat multiple resistant bacteria by targeting the bacterial cell membrane. The components and conformations of antimicrobial peptides are extensively explored to achieve broad-spectrum and effective antimicrobial activity. Here, star-shaped antimicrobial polypeptides are fabricated by employing homologs of poly(l-lysine)s (i.e., poly(l-ornithine)s, poly(l-lysine)s, and poly(l-α,ζ-diaminoheptylic acid)s) with the aim of modulating their charge/hydrophobicity balance and rationalizing their structure-antimicrobial property relationships. The in vitro antibacterial investigation reveals that unnatural amino-acid-based star-shaped poly(l-ornithine)s have remarkable proteolytic stability, excellent biofilm-disrupting capacity, and broad-spectrum antimicrobial activity, even against difficult-to-kill Gram-negative Pseudomonas aeruginosa. Furthermore, star-shaped poly(l-ornithine)s significantly reduce the microbial burden and improve the burn wound healing of mouse skin infected with P. aeruginosa. These results demonstrate that unnatural amino-acid-based star-shaped poly(l-ornithine)s can serve as emerging long-term and biofilm-disrupting antimicrobial agents to treat biofilm-related infections in burn, especially caused by notorious P. aeruginosa.

RevDate: 2020-09-06

Cheng P, Chu R, Zhang X, et al (2020)

Screening of the dominant Chlorella pyrenoidosa for biofilm attached culture and feed production while treating swine wastewater.

Bioresource technology, 318:124054 pii:S0960-8524(20)31326-2 [Epub ahead of print].

This research 12 microalgal species were screened for biofilm attached culture in the treatment of anaerobically digested swine wastewater (ADSW). The influence of ADSW on biomass productivity and removal efficiencies were evaluated using biofilm attached culture with the selected Chlorella pyrenoidosa. The variation of nutritional components from algal cells were further analysed to evaluate the potential applications of C. pyrenoidosa. The results showed that C. pyrenoidosa had the highest tolerance to ADSW, and the highest removal efficiencies for wastewater pollutants were reached when cultured in 5 times diluted ADSW. These test conditions resulted in an algal cell biomass composed of 57.30% proteins, 14.87% extracellular polysaccharide, 3.08% crude fibre, 5.57% crude ash, 2.85% moisture. Amino acids in proteins contained 21.73% essential amino acids and the EAA/NEAA value was 0.64. The essential amino acid score indicates that the selected C. pyrenoidosa could be a good protein source for feed addition.

RevDate: 2020-09-06

Bunse P, Orschler L, Agrawal S, et al (2020)

Membrane Aerated Biofilm Reactors for mainstream partial nitritation / anammox: Experiences using real municipal wastewater.

Water research, 186:116351 pii:S0043-1354(20)30887-3 [Epub ahead of print].

This study investigated the potential of Membrane-Aerated Biofilm Reactors (MABRs) for mainstream nitrogen removal via partial nitration / anaerobic ammonium oxidation (anammox). Four laboratory-scale MABRs were operated with real municipal wastewater characterized by low concentrations of nitrogen (varying between 31 - 120 mg-NH4-N L-1) and the presence of biodegradable organic carbon (soluble COD (sCOD) between 7 and 230 mg-O2 L-1). Two reactors were operated with different aeration strategies (intermittent vs. continuous), the other two with differences in biomass retention (recirculation or removal of detached biomass). Keeping a constant HRT caused instabilities due to difficulties with setting the optimal oxygen flux for the respective surface loadings (1.6 - 6 g-NH4-N m-² d-1). Operating the MABRs with a constant surface loading (2 g-NH4-N m-² d-1) resulted in higher and more stable total nitrogen (TN) removal independent of the aeration strategy. The intermittently aerated MABR improved from an average TN removal of 23 % to 69 %, the continuously aerated MABR from 20 % to 50 % TN removal. Independent of the feeding strategy, the continuously aerated reactor removed slightly more ammonium (80 - 95 %) compared to the intermittently aerated reactor (74 - 93 %). Limiting the oxygen supply by intermittent aeration proofed successful to favor partial nitritation and anammox. Continuous aeration did not achieve stable suppression of nitrite oxidizing bacteria (NOB). Of the removed ammonium, approx. 26 % were left in the effluent as nitrate (only 10 % with intermittent aeration). Recirculation of the detached biomass resulted in reattachment onto the biofilm or membrane surface. This recirculation led to significantly higher biomass retention times and thus to better performance. Removing detached biofilm from the reactor caused a slightly lower TN removal of 33 % compared to 45 % with reattachment, while average ammonium removal was 58 % compared to 63 %, respectively. Scouring events had a significant impact on the overall operation, resulting in short term losses of TN removal capacities of 50 - 100 %. The microbial community composition was different depending on the aeration strategy and biomass retention. The continuously aerated reactor contained significantly more AOB than the intermittently aerated MABR. The reactor with biomass retention contained less ammonium oxidizing bacteria (AOB), compared to the reactor with low biomass retention. In all MABRs, anammox bacteria established in the biofilm after an initial drop in abundance.

RevDate: 2020-09-03

Turrini P, Tescari M, Visaggio D, et al (2020)

The microbial community of a biofilm lining the wall of a pristine cave in Western New Guinea.

Microbiological research, 241:126584 pii:S0944-5013(20)30452-3 [Epub ahead of print].

Caves are extreme environments inhabited by microbial communities adapted to thrive oligotrophic conditions. Cave microbes are organised in complex ecological networks and have developed survival strategies involving the production and release of a large variety of secondary metabolites, including antibiotic-like compounds. In this study, the structure and the metabolic features of a biofilm-like microbial community lining the walls of a pristine karst cavity (the Yumugi river cave) located in a remote region of the Western New Guinea were investigated. 16S rRNA and shotgun sequence analyses highlighted the prevalence of chemoorganotrophic phyla (Proteobacteria, Actinobacteria, Firmicutes and Acidobacteria), consistent with metabolic predictions inferred from the cave metagenome analysis. Few clinically relevant antimicrobial resistance genes were detected. A culture-based approach allowed the isolation of some heterotrophic members of the bacterial community, and antimicrobial susceptibility testing revealed an overall high level of resistance to different antimicrobials classes. Isolates presumptively representing new uncharacterized members of genus Pseudomonas displayed interesting antibiotic properties against Gram-positive indicator strains. Our work supports the hypothesis that caves represent a reservoir for new bacterial species and drug discovery research.

RevDate: 2020-09-03

Mirzaie A, Peirovi N, Akbarzadeh I, et al (2020)

Preparation and optimization of ciprofloxacin encapsulated niosomes: A new approach for enhanced antibacterial activity, biofilm inhibition and reduced antibiotic resistance in ciprofloxacin-resistant methicillin-resistance Staphylococcus aureus.

Bioorganic chemistry, 103:104231 pii:S0045-2068(20)31528-5 [Epub ahead of print].

Ciprofloxacin is an alternative to vancomycin for treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. The objective of this study was to optimization of niosomes encapsulated ciprofloxacin and evaluate their antibacterial and anti-biofilm efficacies against ciprofloxacin-resistant methicillin-resistant S. aureus (CR-MRSA) strains. Formulation of niosomes encapsulated ciprofloxacin were optimized by changing the proportions of Tween 60, Span 60, and cholesterol. The optimized ciprofloxacin encapsulated niosomal formulations based on Span 60 and Tween 60 were prepared and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The SEM and TEM results showed that the formulation of niosomes encapsulated ciprofloxacin were spherical with a size between 50 and 150 nm. The prepared niosomal formulations showed high storage stability up to 30 days with the slight change in size and drug entrapment during the storage, making them good candidates for drug delivery systems. Optimum niosome encapsulated ciprofloxacin enhanced antibacterial activity against CR-MRSA strains via reduction in minimum inhibitory concentration (MIC) value and inhibited significantly biofilm formation. Niosome encapsulated ciprofloxacin down-regulated the expression of icaB biofilm formation gene. Our results showed that encapsulating ciprofloxacin in niosomes is a promising approach to enhanced antibacterial activity, biofilm inhibition and reduced resistance to antibiotic in CR-MRSA strains.

RevDate: 2020-09-03

Gharieb R, Saad M, Abdallah K, et al (2020)

Insights on Toxin Genotyping, Virulence, Antibiogram Profiling, Biofilm Formation, and Efficacy of Disinfectants on Biofilms of Clostridium perfringens Isolated from Poultry, Animals, and Humans.

Journal of applied microbiology [Epub ahead of print].

AIMS: This study aimed to determine the toxin genotypes, virulence determinants, and antibiogram of Clostridium perfringens isolated from poultry, animals, and humans. Biofilm formation and the efficacy of disinfectants on C. perfringens biofilms were studied.

METHODS AND RESULTS: Thirty C. perfringens isolates (20 clinical and 10 from chicken carcasses) were genotyped by PCR and all isolates were genotype A (cpa+). The overall prevalence of cpe, cpb2, netB and tpeL virulence genes was 6.7, 56.7, 56.7 and 36.7%, respectively. Twenty-one isolates (70%) were multidrug-resistant, 8 (26.7%) were extensive drug-resistant and one isolate (3.3%) was pan drug-resistant. The average multiple antibiotic resistance index was 0.7. Biofilms were produced by 63.3% of C. perfringens isolates and categorized as weak (36.7%), moderate (16.7%) and strong (10%). Sodium hypochlorite caused significant reduction in C. perfringens biofilms (P<0.0001).

CONCLUSIONS: All C. perfringens strains in this study were type A, resistant to multiple antibiotics and most of them were biofilm producers. Sodium hypochlorite showed higher efficacy in reducing C. perfringens biofilms.

This study reported the efficacy of disinfectants in reducing C. perfringens biofilms of economic and public health concern and recommends application on surfaces in farms, food processing plants and slaughterhouses.

RevDate: 2020-09-03

Banerjee A, Batabyal K, Singh AD, et al (2020)

Multi-drug resistant, biofilm producing high-risk clonal lineage of Klebsiella in companion and household animals.

Letters in applied microbiology [Epub ahead of print].

Antimicrobial resistance is a global emergency which needs one health approach to address. The present study was conducted to detect the prevalence of beta-lactamase and biofilm-producing-Klebsiella strains in rectal swabs (n=624) collected from healthy dogs, cats, sheep and goats reared as companion or household animals in India. The dogs and cats were frequently exposed to third or fourth generation cephalosporins for therapy.The sheep and goats were occasionally exposed to antibiotics and had environmental exposure.Phenotypical ESBL (n=93) and ACBL (n=88) producing-Klebsiella were isolated significantly more (p<0.05) from companion animals than household animals. Majority of the Klebsiella possessed blaCTX-M-15 .The sequences blaCTX-M-15.2 , blaCTX-M-197 , blaCTX-M-225 is reported first time from the companion animals. All ACBL-producing isolates possessed blaAmpC. The present study detected 65.8% of Klebsiella strains as biofilm producers possessing the studied biofilm associated genes.The isolates showed phenotypical resistance against chloramphenicol, tetracycline, doxycycline, co-trimoxazole, ampicillin, cefotaxime/clavulanic acid. The present study showed that companion and household animals (dogs, cats, sheep, goats) may act as a carrier of ESBL / biofilm producing, multi-drug resistant, high-risk clonal lineage of Klebsiella.

RevDate: 2020-09-03

Pereira TC, Dijkstra RJB, Petridis X, et al (2020)

Chemical and mechanical influence of root canal irrigation on biofilm removal from lateral morphological features of simulated root canals, dentine disks and dentinal tubules.

International endodontic journal [Epub ahead of print].

AIM: To investigate the anti-biofilm efficacy of irrigation using a simulated root canal model, the chemical effect of irrigants against biofilms grown on dentine discs and their impact on biofilm viscoelasticity, the efficacy of the irrigants in decontaminating infected dentinal tubules and the capacity of bacteria to re-grow.

METHODOLOGY: Biofilm removal, viscoelastic analysis of remaining biofilms and bacterial viability were evaluated using a simulated root canal model with lateral morphological features, dentine discs and a dentinal tubule model, respectively. Experiments were conducted using a two-phase irrigation protocol. Phase 1: a modified salt solution (RISA) and sodium hypochlorite (NaOCl) were used at a low flow rate to evaluate the chemical action of the irrigants. Ultrasonic activation (US) of a chemically inert solution (buffer) was used to evaluate the mechanical efficacy of irrigation. Phase 2: a final irrigation with buffer at a high flow rate was performed for all groups. Optical coherence tomography (OCT), low load compression testing (LLCT) and confocal scanning laser microscopy (CSLM) analysis were used in the different models. One-way analysis of variance (ANOVA) was performed for the OCT and LLCT analysis, while Kruskal-Wallisand Wilcoxon ranked tests for the dentinal tubule model.

RESULTS: US and high flow rate removed significantly more biofilm from the artificial lateral canal. For biofilm removal from the artificial isthmus, no significant differences were found between the groups. Within-group analysis revealed significant differences between the steps of the experiment, with the exception of NaOCl. For the dentine discs, no significant differences regarding biofilm removal and viscoelasticity were detected. In the dentinal tubule model, NaOCl exhibited the greatest anti-biofilm efficacy.

CONCLUSIONS: The mechanical effect of irrigation is important for biofilm removal. An extra high flow irrigation rate resulted in greater biofilm removal than US in the artificial isthmus. The mechanical effect of US seemed to be more effective when the surface contact biofilm-irrigant was small. After the irrigation procedures, the remaining biofilm could survive after a 5-days period. RISA and NaOCl seemed to alter post-treatment remaining biofilms.

RevDate: 2020-09-03

Kim HS, Cha E, Ham SY, et al (2020)

Linoleic acid inhibits Pseudomonas aeruginosa biofilm formation by activating diffusible signal factor mediated quorum sensing.

Biotechnology and bioengineering [Epub ahead of print].

Bacterial biofilm formation causes serious problems in various fields of medical, clinical, and industrial settings. Antibiotics and biocide treatments are typical methods used to remove bacterial biofilms, but biofilms are difficult to remove effectively from surfaces due to their increased resistance. An alternative approach to treatment with antimicrobial agents is using biofilm inhibitors that regulate biofilm development without inhibiting bacterial growth. In the present study, we found that linoleic acid, a plant unsaturated fatty acid, inhibits biofilm formation under static and continuous conditions without inhibiting the growth of Pseudomonas aeruginosa. Linoleic acid also influenced the bacterial motility, extracellular polymeric substance production, and biofilm dispersion by decreasing the intracellular cyclic diguanylate concentration through increased phosphodiesterase activity. Furthermore, quantitative gene expression analysis demonstrated that linoleic acid induced the expression of genes associated with diffusible signaling factor-mediated quorum sensing that can inhibit or induce the dispersion of P. aeruginosa biofilms. These results suggest that linoleic acid is functionally and structurally similar to a P. aeruginosa diffusible signaling factor (cis-2-decenoic acid) and, in turn, act as an agonist molecule in biofilm dispersion. This article is protected by copyright. All rights reserved.

RevDate: 2020-09-03

Pu H, Xu Y, Sun DW, et al (2020)

Optical nanosensors for biofilm detection in the food industry: principles, applications and challenges.

Critical reviews in food science and nutrition [Epub ahead of print].

Biofilms are the universal lifestyle of bacteria enclosed in extracellular polymeric substances (EPS) on the contact surfaces of food processing facilities. The EPS-encapsulated foodborne bacterial pathogens are the main food contaminant sources, posing a serious threat to human health. The microcrystalline, sophisticated and dynamic biofilms necessitate the development of conventional microscopic imaging and spectral technology. Nanosensors, which can transfer the biochemical information into optical signals, have recently emerged for biofilm optical detection with high sensitivity and high spatial resolution at nanoscale scopes. Therefore, the aim of this review is to clarify the main detection scope in biofilms and the detection principles of optical nanosensors arousing Raman enhancement, fluoresce conversion and color change. The difficulties and challenges of biofilm characterization including the secretion and variation of main biochemical components are first discussed, the details about the principles and application examples of bioassays targeting foodborne pathogens based on optical nanosensors are then summarized. Finally, the challenges and future trends in developing optical nanosensors are also highlighted. The current review indicates that optical nanosensors have taken the challenges of detecting biofilm in complex food samples, including the characterization of biofilm formation mechanism, identification of microbial metabolic activities, diagnosis of potential food pathogens and sanitation monitoring of food processing equipment. Numerous in-depth explorations and various trials have proven that the bioassays based on multifunctional optical nanosensors are promising to ensure and promote food safety and quality. However, there still remains a daunting challenge to structure reproducible, biocompatible and applicable nano-sensors for biofilm characterization, identification, and imaging.

RevDate: 2020-09-05

White JK, Nielsen JL, Larsen CM, et al (2020)

Impact of dust on airborne Staphylococcus aureus' viability, culturability, inflammogenicity, and biofilm forming capacity.

International journal of hygiene and environmental health, 230:113608 pii:S1438-4639(20)30554-X [Epub ahead of print].

Staphylococcus aureus is an opportunistic pathogen associated with soft-tissue infections commonly encountered in indoor and farm environments as a component of airborne dust, which can potentially deposit in the respiratory tracts of workers and residents. However, knowledge regarding the survival and inflammatory potential of S. aureus in airborne dust has not been described. The objective of this study was to obtain knowledge on whether the presence of dust during aerosolisation affects the culturability (ability to grow on agar plates), their biofilm forming capacity, viability (using a viability qPCR), and inflammatory potential (using a human granulocyte based assay), and whether time from aerosolisation to subsequent analyses (the resting time) affects these. Aerosols containing S. aureus (DSM6148) in the presence of sterilised airborne dust from a pig farm were found to have higher culturability, viability, inflammatory potential, and ability to form biofilm compared with S. aureus aerosols generated without airborne dust. When aerosols of S. aureus were generated without dust, they showed a reduction in the culturability, as well as the biofilm forming capacity and an extended resting time was associated with a reduction in culturability, and biofilm forming capacity. In contrast, no differences in the viability were observed in samples with different resting times. The lack of a significant effect of different resting times on viability, and the significant effect on culturability, suggests that the stresses of aerosolisation may induce a viable, but not culturable (VBNC) state in S. aureus. A synergistic effect was found between S. aureus and dust concerning their ability to induce inflammation. In conclusion presence of airborne dust during aerosolisation of S. aureus affects the culturability, biofilm forming capacity, and inflammatory potential, but not the viability of S. aureus. This is of importance in relation to hygiene as well as how exposure to S. aureus is measured.

RevDate: 2020-09-05

Sari S, Koçak E, Kart D, et al (2020)

Azole derivatives with naphthalene showing potent antifungal effects against planktonic and biofilm forms of Candida spp.: an in vitro and in silico study.

International microbiology : the official journal of the Spanish Society for Microbiology pii:10.1007/s10123-020-00144-y [Epub ahead of print].

Candida infections pose a serious public health threat due to increasing drug resistance. Azoles are first-line antifungal drugs for fungal infections. In this study, we tested an in-house azole collection incorporating naphthalene ring to find hits against planktonic and biofilm forms of resistant Candida spp. In the collection, potent derivatives were identified against the susceptible strains of Candida with minimum inhibitory concentration (MIC) values lower than those of the reference drug, fluconazole. MIC values of 0.125 μg/ml against C. albicans, 0.0625 μg/ml against C. parapsilosis, and 2 μg/ml against C. krusei, an intrinsically azole-resistant non-albicans Candida, were obtained. Some of the derivatives were highly active against fluconazole-resistant clinical isolate of C. tropicalis. Inhibition of C. albicans biofilms was also observed at 4 μg/ml similar as amphotericin B, the reference drug known for its antibiofilm activity. Through molecular docking studies, affinities and key interactions of the compounds with fungal lanosterol 14α-demethylase (CYP51), the target enzyme of azoles, were predicted. The interactions of imidazole with heme cofactor and of the naphthalene with Tyr118 were highlighted in line with the literature data. As a result, this study proves the importance of naphthalene for the antifungal activity of azoles against Candida spp. in both planktonic and biofilm forms.

RevDate: 2020-09-05

Aydin S, K Can (2020)

Pyophage cocktail for the biocontrol of membrane fouling and its effect in aerobic microbial biofilm community during the treatment of antibiotics.

Bioresource technology, 318:123965 pii:S0960-8524(20)31237-2 [Epub ahead of print].

Membrane bioreactor systems face an inevitable challenge that is biofouling, which not only hinders the operation of the system, but also poses an environmental and medical concern caused by the increased antibiotic resistance in bacterial biofilms. This study investigates the disruption of membrane fouling using bacteriophage cocktail (Pyophage) in an aerobic membrane bioreactor for treatment of wastewater containing high non-lethal concentration of erythromycin, tetracycline and sulfamethoxazole, while also considering the effect of the cocktail on performance. The results indicate that Pyophage cocktail contributes significantly to the decrease (45%) in transmembrane pressure while also suppressing biofilm-producing bacteria compared to the control reactors. It also reconstructed biodegradation mechanism of antibiotics especially increasing the relative abundance of gram-negative bacteria by enhancement the removal rate of erythromycin and sulfamethoxazole from the aerobic system to 99%.

RevDate: 2020-09-05

Zhou W, Peng X, Zhou X, et al (2020)

Novel Nanocomposite Inhibiting Caries at the Enamel Restoration Margins in an In Vitro Saliva-Derived Biofilm Secondary Caries Model.

International journal of molecular sciences, 21(17): pii:ijms21176369.

Secondary caries often occurs at the tooth-composite margins. This study developed a novel bioactive composite containing DMAHDM (dimethylaminohexadecyl methacrylate) and NACP (nanoparticles of amorphous calcium phosphate), inhibiting caries at the enamel restoration margins in an in vitro saliva-derived biofilm secondary caries model for the first time. Four composites were tested: (1) Heliomolar nanocomposite, (2) 0% DMAHDM + 0% NACP, (3) 3% DMAHDM + 0% NACP, (D) 3% DMAHDM + 30% NACP. Saliva-derived biofilms were tested for antibacterial effects of the composites. Bovine enamel restorations were cultured with biofilms, Ca and P ion release of nanocomposite and enamel hardness at the enamel restoration margins was measured. Incorporation of DMAHDM and NACP into composite did not affect the mechanical properties (p > 0.05). The biofilms' CFU (colony-forming units) were reduced by 2 logs via DMAHDM (p < 0.05). Ca and P ion release of the nanocomposite was increased at cariogenic low pH. Enamel hardness at the margins for DMAHDM group was 25% higher than control (p < 0.05). With DMAHDM + NACP, the enamel hardness was the greatest and about 50% higher than control (p < 0.05). Therefore, the novel composite containing DMAHDM and NACP was strongly antibacterial and inhibited enamel demineralization, resulting in enamel hardness at the margins under biofilms that approached the hardness of healthy enamel.

RevDate: 2020-09-05

Paduszynska MA, Greber KE, Paduszynski W, et al (2020)

Activity of Temporin A and Short Lipopeptides Combined with Gentamicin against Biofilm Formed by Staphylococcusaureus and Pseudomonas aeruginosa.

Antibiotics (Basel, Switzerland), 9(9): pii:antibiotics9090566.

The formation of biofilms on biomaterials causes biofilm-associated infections. Available treatments often fail to fight the microorganisms in the biofilm, creating serious risks for patient well-being and life. Due to their significant antibiofilm activities, antimicrobial peptides are being intensively investigated in this regard. A promising approach is a combination therapy that aims to increase the efficacy and broaden the spectrum of antibiotics. The main goal of this study was to evaluate the antimicrobial efficacy of temporin A and the short lipopeptides (C10)2-KKKK-NH2 and (C12)2-KKKK-NH2 in combination with gentamicin against biofilm formed by Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA). Peptides were synthesized with solid-phase temperature-assisted synthesis methodology. The minimum inhibitory concentrations (MICs), fractional inhibitory concentrations (FICs), minimum biofilm eradication concentrations (MBECs), and the influence of combinations of compounds with gentamicin on bacterial biofilm were determined for reference strains of SA (ATCC 25923) and PA (ATCC 9027). The peptides exhibited significant potential to enhance the antibacterial activity of gentamicin against SA biofilm, but there was no synergy in activity against planktonic cells. The antibiotic applied alone demonstrated strong activity against planktonic cells and poor effectiveness against SA biofilm. Biofilm formed by PA was much more sensitive to gentamicin, but some positive influences of supplementation with peptides were noticed. The results of the performed experiments suggest that the potential application of peptides as adjuvant agents in the treatment of biofilm-associated infections should be studied further.

RevDate: 2020-09-04

Zhang B, Yu P, Wang Z, et al (2020)

Hormetic Promotion of Biofilm Growth by Polyvalent Bacteriophages at Low Concentrations.

Environmental science & technology [Epub ahead of print].

Interactions between bacteriophages (phages) and biofilms are poorly understood despite their broad ecological and water quality implications. Here, we report that biofilm exposure to lytic polyvalent phages at low concentrations (i.e., 102 - 104 phages/mL) can counterintuitively promote biofilm growth and densification (corroborated by confocal laser scanning microscopy). Such exposure hormetically upregulated quorum sensing genes (by 4.1- to 24.9-fold), polysaccharide production genes (by 3.7- to 9.3-fold) and curli synthesis genes (by 4.5- to 6.5-fold) in the biofilm-dwelling bacterial hosts (i.e., Escherichia coli and Pseudomonas aeruginosa) relative to unexposed controls. Accordingly, the biofilm matrix increased its polysaccharide and extracellular DNA content relative to unexposed controls (by 41.8 ± 2.3 % and 81.4 ± 2.2 %, respectively), which decreased biofilm permeability and increased structural integrity. This contributed to enhanced resistance to disinfection with chlorine (bacteria half-lives were 6.08±0.05 min vs. 3.91±0.03 min for unexposed controls) and to subsequent phage infection (biomass removal was 18.2 ± 1.2% vs 32.3 ± 1.2% for unexposed controls), apparently by mitigating diffusion of these antibacterial agents through the biofilm. Overall, low concentrations of phages reaching a biofilm may result in unintended biofilm stimulation, which might accelerate biofouling, biocorrosion or other biofilm-related water quality problems.

RevDate: 2020-09-04

Sen S, Borah SN, Bora A, et al (2020)

Rhamnolipid exhibits anti-biofilm activity against the dermatophytic fungi Trichophyton rubrum and Trichophyton mentagrophytes.

Biotechnology reports (Amsterdam, Netherlands), 27:e00516 pii:e00516.

Dermatophytes are responsible for a majority of fungal infections in humans and other vertebrates, causing dermatophytosis. Treatment failures are often associated with biofilm formation, making dermatophytes resistant to antifungals. In this study, effects of a rhamnolipid (RL-SS14) produced by Pseudomonas aeruginosa SS14 on planktonic cells of Trichophyton rubrum and Trichophyton mentagrophytes, their biofilm formation, and disruption of mature biofilms were assessed. The composition of RL-SS14 was analysed using FTIR, HPLC-ESI-MS, and GC-MS. Minimum inhibitory concentrations against the planktonic forms of T. rubrum and T. mentagrophytes were 0.5 mg/mL and 0.125 mg/mL, respectively. Crystal-violet (biofilm biomass) and safranin (extracellular matrix) staining revealed that RL-SS14 significantly inhibited biofilm formation and also reduced preformed biofilms in a dose-dependent manner. Microscopic visualization of treated biofilms via SEM, AFM, and CLSM revealed marked morphological damage, cell death, and reduced extracellular matrix. The results indicate the potential of RL-SS14 as an anti-biofilm agent against dermatophytes.

RevDate: 2020-09-04

Irshad MS, Arshad N, Ahmed I, et al (2020)

Low-cost green recyclable biomaterial for energy-dependent electrical switching and intact biofilm with antibacterial properties.

Scientific reports, 10(1):14600 pii:10.1038/s41598-020-71610-w.

A highly cost-effective recycled biomaterial extracted from lime peel has been made biocompatible and has been coated on a commercial fluorine-doped tin oxide (FTO) substrate of glass using the spin coating method. Structural, morphologic, electronic, and antibacterial measurements were thoroughly characterized as a green biomaterial thin film using X-rays (XRD), PL, FTIR, Raman, SEM, HRTEM, AFM, I-V, and antibacterial diffusion techniques. The comprehensive analysis of structures of recyclable waste in the form of lime peel extract (LPE) as thin films showed the crystalline cellulose structure that corresponds to the lattice fringe (0.342 nm) exposed by HRTEM. The K+1 interstitial active sites or vacancies in LPE/FTO thin films are confirmed by the PL spectra that show important evidence about conduction mechanisms, and hence facilitates Ag+1 ion migration from the top to the bottom electrode. The AFM investigations revealed the minor surface roughness (169.61 nm) of the LPE/FTO film, which controls the current leakage that is associated with surface defects. The designed memory cell (Ag/LPE/FTO) exhibits stable, reproducible electrical switching under low operational voltage and is equipped with excellent retention over 5 × 103 s. Furthermore, owing to presence of flavonoids and their superior antioxidant nature, lime peel extract powder shows tremendous antimicrobial activity against gram-positive and Gram-negative bacterial strains.

RevDate: 2020-09-04

Das AK, Dudeja M, Kohli S, et al (2020)

Biofilm synthesis and other virulence factors in multidrug-resistant uropathogenic enterococci isolated in Northern India.

Indian journal of medical microbiology, 38(2):200-209.

Purpose: Enterococci express high degree of resistance towards wide range of antibiotics. Production of biofilm and many virulence factors along with drug resistance makes it difficult to eradicate the infection from urinary tract. The present study detected the expression of such factors including biofilm production by multidrug-resistant (MDR) enterococci.

Materials and Methods: Drug susceptibility of 103 uropathogenic enterococci was performed followed by estimation of minimum inhibitory concentration of high-level gentamicin and vancomycin by microbroth dilution method. Vancomycin-resistant genes were detected by multiplex polymerase chain reaction. Production of virulence factors such as haemagglutination, caseinase, lipase, gelatinase, haemolysin and β-lactamase was detected by phenotypic methods in MDR strains. Biofilm production was detected by calcofluor-white fluorescence staining and semi-quantitative adherence assay.

Results: 45% and 18.4% of the isolates were high-level gentamicin-resistant and vancomycin-resistant enterococci (VRE), respectively. vanA gene was detected in 14 and vanB gene in 5 strains. Biofilm, caseinase and gelatinase were the most expressed virulence factor. Expression of caseinase, gelatinase and lipase was significantly higher in Enterococcus faecalis (P < 0.05). Expression of haemagglutination, gelatinase and haemolysin among the vancomycin-resistant isolates was significantly higher (P < 0.05).

Conclusion: VanA and vanB are the prevalent genotypes responsible for vancomycin resistance. The high prevalence of MDR enterococcal strains producing biofilm and virulence determinants raises concern. asa1, hyl, esp, gelE, cyl and other genes are known to express these factors and contribute to biofilm formation. Most uropathogenic enterococci expressed biofilm at moderate level and can be detected effectively by calcofluor-white staining. No correlation was noted between vancomycin resistance and biofilm production.

RevDate: 2020-09-04

Pinel ISM, Kim LH, Proença Borges VR, et al (2020)

Effect of phosphate availability on biofilm formation in cooling towers.

Biofouling [Epub ahead of print].

Phosphate limitation has been suggested as a preventive method against biofilms. P-limited feed water was studied as a preventive strategy against biofouling in cooling towers (CTs). Three pilot-scale open recirculating CTs were operated in parallel for five weeks. RO permeate was fed to the CTs (1) without supplementation (reference), (2) with supplementation by biodegradable carbon (P-limited) and (3) with supplementation of all nutrients (non-P-limited). The P-limited water contained ≤10 µg PO4 l-1. Investigating the CT-basins and coupons showed that P-limited water (1) did not prevent biofilm formation and (2) resulted in a higher volume of organic matter per unit of active biomass compared with the other CTs. Exposure to external conditions and cycle of concentration were likely factors that allowed a P concentration sufficient to cause extensive biofouling despite being the limiting compound. In conclusion, phosphate limitation in cooling water is not a suitable strategy for CT biofouling control.

RevDate: 2020-09-03

Kim HJ, Cho MY, Lee ES, et al (2020)

Effects of short-time exposure of surface pre-reacted glass-ionomer eluate on dental microcosm biofilm.

Scientific reports, 10(1):14425 pii:10.1038/s41598-020-71363-6.

This study evaluated the antibacterial effects of short-time exposure of surface pre-reacted glass-ionomer (S-PRG) eluate on oral microcosm biofilm. Biofilms were treated with an S-PRG eluate at different concentrations (25%, 50%, and 100%), distilled water (DW), and 0.1% chlorhexidine (CHX) twice a day for 5 min repeatedly. After 7 days, the total and aciduric bacterial counts and biofilm dry weights were measured. An image analysis program calculated the red/green (R/G) ratios in the biofilm autofluorescence images. Microscopic analyses quantified the biofilm thickness and live/dead cell ratio and determined morphological changes in the biofilm. Bacterial counts and dry weights were not significantly different in the DW group for all S-PRG eluate concentrations. An increasing trend in the R/G ratio for 7 days biofilm treatment was observed for the S-PRG eluate and the DW groups. Furthermore, the live/dead cell ratios in the biofilm and the biofilm thickness of the S-PRG eluate groups were similar to those of the DW group. The bacteria morphology inside the biofilm changed only in the CHX group. Short-time S-PRG eluate treatment showed no significant antibacterial and antibiofilm effects. These results indicated that limited biofilm formation inhibition can be obtained by using only the S-PRG eluate.

RevDate: 2020-09-03

Galván-Pacheco J, Vitales-Noyola M, González-Amaro AM, et al (2020)

Evaluation of in vitro biofilm elimination of Enterococcus faecalis using a continuous ultrasonic irrigation device.

Journal of oral science [Epub ahead of print].

This study sought to evaluate biofilm elimination using the HBW Ultrasonic Ring based on continuous ultrasonic irrigation. Forty-five premolars and molars with complex curvatures were included. An Enterococcus faecalis biofilm was established for 30 days on the extracted teeth. The teeth were then stratified into three experimental groups for instrumentation and irrigation (i.e. HBW Ultrasonic Ring, conventional irrigation, and passive ultrasonic irrigation). Pre- and post-instrumentation samples were collected, and reductions of bacterial load were evaluated by McFarland's scale, counting of colony-forming units, and scanning electronic microscopy. The HBW Ultrasonic Ring promoted a higher reduction in bacterial load relative to conventional irrigation (P < 0.05) and a similar reduction compared with passive ultrasonic irrigation (P > 0.05). These results suggest the HBW Ultrasonic Ring is a promising alternative modality for simultaneous instrumentation and irrigation during root canal treatment, achieving an appropriate level of bacterial reduction and allowing the passage of the irrigating solution throughout the entire working length.

RevDate: 2020-09-03

Hunt CM, Collins CM, MQ Benedict (2020)

Measuring and reducing biofilm in mosquito rearing containers.

Parasites & vectors, 13(1):439 pii:10.1186/s13071-020-04315-8.

BACKGROUND: Mosquito rearing containers contain organic-rich water that nourishes numerous bacteria, some of which are capable of forming biofilms. Biofilm is broadly an extracellular polymeric matrix (EPS) in which living bacteria occur, and the accumulation of biofilm is possible during routine stock-keeping as most of these containers are re-used. Whether biofilm has an effect on the mosquito rearing is not a question that has been investigated, nor have measures to reduce biofilm in this context been systematically studied.

METHODS: We measured biofilm accumulation in standard rearing containers by staining with crystal violet and determining the OD using a spectrophotometer. We also treated rearing containers with 0.1% sodium hypochlorite to determine its effectiveness in reducing biofilm abundance. Lastly, we performed an analysis of the relationship between the occurrence of biofilm and the likelihood of microbial blooms that were associated with larval death during trials of larval diets.

RESULTS: We observed that soaking rearing containers overnight in 0.1% sodium hypochlorite greatly reduced biofilm, but we observed no relationship between the use of containers that had not been treated with bleach and subsequent microbial blooms.

CONCLUSIONS: Larva rearing leaves detectable biofilm. While we were unable to correlate microbial blooms with the presence of biofilm, as a precaution, we recommend that plastic containers that are re-used be treated with 0.1% sodium hypochlorite occasionally.

RevDate: 2020-09-02

Guo P, Yi Xue H, Buttaro BA, et al (2020)

Manuscript for International Journal of Pharmaceutics Enhanced eradication of intracellular and biofilm-residing methicillin-resistant Staphylococcus aureus (MRSA) reservoirs with hybrid nanoparticles delivering rifampicin.

International journal of pharmaceutics pii:S0378-5173(20)30769-9 [Epub ahead of print].

Osteomyelitis carries a high risk of recurrence even after extended, aggressive antibiotic therapy. One of the key challenges is to eradicate the reservoirs of methicillin-resistant Staphylococcus aureus (MRSA) inside the host bone cells and their biofilms. Our goal is to develop rifampicin loaded lipid-polymer hybrid nanocarriers (Rf-LPN) and evaluate if they can achieve enhanced rifampicin delivery to eradicate these intracellular and biofilm-residing MRSA. After optimization of the composition, Rf-LPN demonstrated size around 110 nm in diameter that remained stable in serum-supplemented medium, drug payload up to 11.7% and sustained rifampicin release for 2 weeks. When comparing Rf-LPN with free rifampicin, moderate but significant (p<0.05) improvement of the activities against three osteomyelitis-causing bacteria (USA300-0114, CDC-587, RP-62A) in planktonic form were observed. In comparison, the enhancements in the activities against the biofilms and intracellular MRSA by Rf-LPN were even more substantial. The MBEC50 values against USA300-0114, CDC-587, and RP-62A were 42 vs 155, 70 vs 388, and 265 ng/ml vs over 400 ng/ml, respectively, and up to 18.5-fold reduction in the intracellular MRSA counts in osteoblasts was obtained. Confocal microscope images confirmed extensive accumulation of Rf-LPN inside the biofilm matrix and MRSA-infected osteoblasts. Overall, in this proof-of-concept study we have developed and validated the strategy to exploit the nanoparticle-cell and nanoparticle-biofilm interactions with a new rifampicin nanoformulation for prevention of osteomyelitis recurrence and chronicity caused by the elusive MRSA.

RevDate: 2020-09-02

Manna S, Ghanty C, Baindara P, et al (2020)

Electrochemical communication in biofilm of bacterial community.

Journal of basic microbiology [Epub ahead of print].

Electrochemical communication during biofilm formation has recently been identified. Bacteria within biofilm-adopt different strategies for electrochemical communication such as direct contact via membrane-bound molecules, diffusive electron transfer via soluble redox-active molecules, and ion channel-mediated long-range electrochemical signaling. Long-range electrical signals are important to communicate with distant members within the biofilm, which function through spatially propagating waves of potassium ion (K+) that depolarizes neighboring cells. During propagation, these waves coordinate between the metabolic states of interior and peripheral cells of the biofilm. The understanding of electrochemical communication within the biofilm may provide new strategies to control biofilm-mediated drug resistance. Here, we summarized the different mechanisms of electrochemical communication among bacterial populations and suggested its possible role in the development of high level of antibiotic resistance. Thus, electrochemical signaling opens a new avenue concerning the electrophysiology of bacterial biofilm and may help to control the biofilm-mediated infection by developing future antimicrobials.

RevDate: 2020-09-03

Astuti SD, Hafidiana , Rulaningtyas R, et al (2020)

The efficacy of photodynamic inactivation with laser diode on Staphylococcus aureus biofilm with various ages of biofilm.

Infectious disease reports, 12(Suppl 1):8736.

Biofilms are able to cause microorganisms to be 80% more resistant to antibiotics. The extracelullar polymeric substance (EPS) in biofilm functions to protect bacteria, making it difficult for antibiotics to penetrate the biofilm layer. This study aims to determine the effectiveness of photodynamic inactivation with blue diode laser to reduce Staphylococcus aureus biofilm at various ages of biofilms. The light source is a 403 nm blue diode laser with an energy power of about 27.65±0.01 mW. The study was designed with two groups: Group C was the untreated control group with variations in age of biofilms (0; 6; 11; 17; 24; 32; 40 and 48) hours; Group T was a laser treatment group with variations in age of biofilm and energy density (4.23; 8.46; 12.70; 16.93 and 21.16) J/cm2. Biofilm reduction measurement method using ELISA test was performed to calculate OD595 value. The statistical analysis results of variance showed that there was an influence of biofilm age and irradiation energy density of laser on biofilm reduction. Optical density analysis showed the most optimum biofilm reduction happened when biofilm age is perfectly constructed (about 17 hours) and with 91% reduction. The longer biofilm age lived among those biofilms, the greater the reduction. The results of the Scanning Microscope Electron and fluorescent microscope measurement showed destruction site of the EPS biofilm and bacterial cell death. So, the activated photodynamic with 403 nm laser diode is effective to reduce the Staphylococcus aureus biofilm in the maturation phase.

RevDate: 2020-09-03

Kriswandini IL, I D, Tantiana , et al (2020)

The forming of bacteria biofilm from Streptococcus mutans and Aggregatibacter actinomycetemcomitans as a marker for early detection in dental caries and periodontitis.

Infectious disease reports, 12(Suppl 1):8722.

Background: This is an initial study of the biofilm of Streptococcus mutans (S.mutans) and Aggregatibacter actinomycetemcomitans (A.a). S. mutans and A.aare bacteria that cause infection diseases in the oral cavity. These bacteria have the ability to form biofilms. The study of bacterial biofilm proteins was used as an alternative to early prevention for oral infections. It would be used for the purpose of creating a marker for Infection Detection Kit in the oral cavity.

Objective: To easily detect caries or Periodontitis with the biofilms of S. mutans and A.a at the early stage. The forming of biofilm proteins from S.mutans and A.a induced with 5% glucose, 5% lactose, 5% soy protein, and 5% iron will be use as a marker for early detection to Dental caries and Periodontitis.

Methods: SDS-PAGE electrophoresis technique was used in the study to measure the molecular weight of S. mutans and A.a biofilms induced with 5% glucose, 5% lactose, 5% soy protein, and 5% iron.

Results: Biofilm bands of S. mutans and A.a were formed with the various numbers depending on the induction used. These results are early chararterization of biofilm that will beused as a marker for early detection of infectious diseases in oral cavity (Dental Caries and Periodontitis).

Conclusions S mutans: bacteria induced with 5% glucose had one band of biofilm protein, with 5% lactose had four bands of biofilm proteins, and with soy protein had seven bands of biofilm protein, but with 5% iron did not produce any protein bands and neither did A.a.

RevDate: 2020-09-02

She Q, Hunter E, Qin Y, et al (2020)

Negative Interplay between Biofilm Formation and Competence in the Environmental Strains of Bacillus subtilis.

mSystems, 5(5): pii:5/5/e00539-20.

Environmental strains of the soil bacterium Bacillus subtilis have valuable applications in agriculture, industry, and biotechnology; however, environmental strains are genetically less accessible. This reduced accessibility is in sharp contrast to laboratory strains, which are well known for their natural competence, and a limitation in their applications. In this study, we observed that robust biofilm formation by environmental strains of B. subtilis greatly reduced the frequency of competent cells in the biofilm. By using model strain 3610, we revealed a cross-pathway regulation that allows biofilm matrix producers and competence-developing cells to undergo mutually exclusive cell differentiation. We further demonstrated that the competence activator ComK represses the key biofilm regulatory gene sinI by directly binding to the sinI promoter, thus blocking competent cells from simultaneously becoming matrix producers. In parallel, the biofilm activator SlrR represses competence through three distinct mechanisms involving both genetic regulation and cell morphological changes. Finally, we discuss the potential implications of limiting competence in a bacterial biofilm.IMPORTANCE The soil bacterium Bacillus subtilis can form robust biofilms, which are important for its survival in the environment. B. subtilis also exhibits natural competence. By investigating competence development in B. subtilisin situ during biofilm formation, we reveal that robust biofilm formation often greatly reduces the frequency of competent cells within the biofilm. We then characterize a cross-pathway regulation that allows cells in these two developmental events to undergo mutually exclusive cell differentiation during biofilm formation. Finally, we discuss potential biological implications of limiting competence in a bacterial biofilm.

RevDate: 2020-09-02

Xu J, Gao Y, Meng Y, et al (2020)

Mechano-chemical coupling of irrigation enhances endodontic biofilm debridement.

Biofouling [Epub ahead of print].

The complexity of the root canal system results in areas where mechanical instrumentation is impossible during endodontic treatment. To disinfect these areas, the effect of irrigation on biofilm debridement is of great significance but has not yet been well explored. Using an in vitro Enterococcus faecalis biofilm model and a biofilm reactor, the present study provides a better understanding of the relative contributions of mechanical and chemical effects of irrigation on biofilm removal, as well as the factors influencing their coupling efficiency. The results clearly demonstrate that, the mechanical effect of irrigation alone does not significantly influence the stability of biofilms. However, the mechanical effect promotes biofilm eradication by coupling with the chemical effect. In addition, both the irrigant concentration and the irrigant-biofilm contact time are among the key factors affecting the mechano-chemical coupling. This knowledge may serve to better direct endodontists in designing irrigation regimes during root canal therapy.

RevDate: 2020-09-02

Wang G, Zhao G, Chao X, et al (2020)

The Characteristic of Virulence, Biofilm and Antibiotic Resistance of Klebsiella pneumoniae.

International journal of environmental research and public health, 17(17): pii:ijerph17176278.

Klebsiella pneumoniae is an important gram-negative opportunistic pathogen that causes a variety of infectious diseases, including urinary tract infections, bacteremia, pneumonia, and liver abscesses. With the emergence of multidrug-resistant (MDR) and hypervirulent K. pneumoniae (hvKP) strains, the rapid spread of these clinical strains in geography is particularly worrying. However, the detailed mechanisms of virulence and antibiotic resistance in K. pneumoniae are still not very clear. Therefore, studying and elucidating the pathogenic mechanisms and drug resistance mechanism of K. pneumoniae infection are important parts of current medical research. In this paper, we systematically summarized the virulence, biofilm, and antibiotic tolerance mechanisms of K. pneumoniae, and explored the application of whole genome sequencing and global proteomics, which will provide new clues for clinical treatment of K. pneumoniae.

RevDate: 2020-09-02

Hall DC, Król JE, Cahill JP, et al (2020)

The Development of a Pipeline for the Identification and Validation of Small-Molecule RelA Inhibitors for Use as Anti-Biofilm Drugs.

Microorganisms, 8(9): pii:microorganisms8091310.

Biofilm infections have no approved effective medical treatments and can only be disrupted via physical means. This means that any biofilm infection that is not addressable surgically can never be eliminated and can only be managed as a chronic disease. Therefore, there is an urgent need for the development of new classes of drugs that can target the metabolic mechanisms within biofilms which render them recalcitrant to traditional antibiotics. Persister cells within the biofilm structure may play a large role in the enhanced antibiotic recalcitrance of bacteria biofilms. Biofilm persister cells can be resistant to up to 1000 times the minimal inhibitory concentrations of many antibiotics, as compared to their planktonic envirovars; they are thought to be the prokaryotic equivalent of metazoan stem cells. Their metabolic resistance has been demonstrated to be an active process induced by the stringent response that is triggered by the ribosomally-associated enzyme RelA in response to amino acid starvation. This 84-kD pyrophosphokinase produces the "magic spot" alarmones, collectively called (p)ppGpp. These alarmones act by directly regulating transcription by binding to RNA polymerase. These transcriptional changes lead to a major shift in cellular function to both upregulate oxidative stress-combating enzymes and down regulate major cellular functions associated with growth and replication. These changes in gene expression produce the quiescent persister cells. In this work, we describe a hybrid in silico laboratory pipeline for identifying and validating small-molecule inhibitors of RelA for use in the combinatorial treatment of bacterial biofilms as re-potentiators of classical antibiotics.

RevDate: 2020-09-01

Zeller B, Stöckli S, Zaugg LK, et al (2020)

Biofilm formation on metal alloys, zirconia and polyetherketoneketone as implant materials in vivo.

Clinical oral implants research [Epub ahead of print].

OBJECTIVES: This study investigated biofilm formation on discs of metal alloys, zirconia, and polyetherketoneketone in vivo.

MATERIAL AND METHODS: Sixteen healthy volunteers conducted two runs of 24 hours each wearing an intraoral splint with 15 discs representing five different materials (gold-based [EL] and silver-based [PA] noble metal alloys; zirconia [ZR]; polyetherketoneketone [PEKK]; titanium zirconium alloy [TiZr]). Safranin staining assays and colony forming unit (CFU) counts were conducted. Linear mixed-effects models were used to compare materials and geometric mean ratios with 95% confidence interval were calculated with the level of significance set at α=0.05.

RESULTS: Less biofilm mass and lower CFU counts were found on PA and EL, while ZR and PEKK developed similar levels as the reference material TiZr alloy. Compared with PA, biofilm mass was 1.5 times higher for EL (p=0.004), 1.7 times higher for PEKK (p<0.001), 2.2 times higher for TiZr (p<0.001), and 2.4 times higher for ZR (p<0.001). The culturing method confirmed these results for EL and PA with lower CFU compared to TiZr. The biomass staining technique and cell culturing correlated for EL and PA.

CONCLUSION: Silver-based noble alloy and gold-based high noble alloy demonstrated the least biofilm formation indicating a potential clinical use as material for implant components in the transmucosal compartment. Zirconia and Polyetherketoneketone revealed similar results as the reference material titanium zirconium alloy used in commercially available titanium dental implant.

RevDate: 2020-09-01

Herrmann H, Kern JS, Kern T, et al (2020)

Early and mature biofilm on four different dental implant materials: an in vivo human study.

Clinical oral implants research [Epub ahead of print].

OBJECTIVES: The aim of this study was to examine the microbial composition of early (after 3 days, D3) and mature biofilms (after 31 days, D31) on materials typically used in implant-abutment build-ups. Implant/abutment materials with different surface roughness values (Ra) were compared to detect differences in the quantity and quality of bacterial composition.

MATERIAL AND METHODS: Four different materials were investigated: rough implant surface (sand-blasted acid-etched titanium; Ti-p), implant collar (machined titanium; Ti-m), titanium abutment (Ti6Al4V), and zirconium-dioxide abutment (ZrO2). Fourteen periodontally healthy subjects received mandibular acrylic devices with four disks (one for each material) facing the anterior lingual area. The total bacterial count was analyzed using RT-qPCR. Both presence and proliferation of 20 selected bacterial species were assessed with microarrays.

RESULTS: The highest mean total cell counts (x108 ±standard deviation) were detected at D3 on ZrO2 (5.63±4.83; Ra =0.74 µm), followed by Ti-p (4.53±5.00; Ra =1.87), Ti-m (4.43±9.38; Ra =0.18 µm), and Ti6Al4V (3.83±3.13; Ra =0.16 µm). ZrO2 showed significantly higher total bacterial cell counts than Ti-p and Ti-m (p<0.05) for both time intervals. The microarrays detected 16 (D3) and 17 (D31) bacterial species; those associated with healthy oral microbiotas, but also bacteria of the red complex (Tannerella forsythia, Treponema denticola), were found on all materials.

CONCLUSIONS: Biofilms on ZrO2 harbored a higher total number of bacterial cells compared with those formed on titanium surfaces with much lower roughness values. Putative periodontopathogens were detected on all materials after both time intervals. Implant/abutment materials with a low surface roughness showed less biofilm accumulation.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.


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This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

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Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )