Biofilm Resistance Research Articles

Molecular mechanisms of biofilm resistance against antibiotics

Biofilms are immobile communities of microbes attached to biotic an abiotic surfaces and are embedded inside a self-produced cement-like extracellular polymeric substances. The resistance of biofilms against commonly used drugs has been implicated in the pathogenesis of various bacterial infections under medical and veterinary settings which normally cannot be eradicated by antibiotics. Biofilms are characterized by the ability to evade not only the antibiotic effects but also the host immune system clearance. Currently the most worrisome aspect of global human health is the rise and spread of antimicrobial resistance in bacterial pathogens and this crisis got deepened by the emergence of antimicrobial resistance of bacterial biofilms. Different antibiotic resistance mechanisms, processes by which a target pathogen curtails the interaction between an antimicrobial agent and its intended target molecules, adopted by biofilms have been discussed in this review. Different antibiotic resistance mechanisms are employed by the biofilms depending on the species of the bacteria, growth conditions, and the antibiotic involved. Commonly, the role of biofilm matrix polysaccharides, antibiotic-modifying or degrading enzymes, extracellular DNA, hypoxic conditions, presence of efflux pumps, quorum sensing, horizontal gene transfer, mutation frequency, etc. have been implicated in antibiotic resistance of biofilms. This review also discusses different approaches of overcoming biofilm infections or biofilm resistance. However, it is pertinent to mention that since no new class of antibiotics have been approved in last four decades there is the need of greater understanding of biofilm-associated antibiotic resistance to effectively utilise the therapeutic value of the existing antibiotics. Although a number of anti-biofilm strategies have been put forward as discussed in this review, they are still in nascent stage and need to undergo clinical trials to reach the commercial market.

A potential role of extracellular DNA in biofilm and ciprofloxacin resistance

Objectives: This study aims to broaden our knowledge of the role of eDNA in bacterial biofilms and antibiotic-resistance gene transfer among isolates.
 Methods: Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa were isolated from different non-repeated 170 specimens. The bacterial isolates were identified using morphological and molecular methods. Different concentrations of genomic DNA were tested for their potential role in biofilms formed by study isolates employing microtiter plate assay. Ciprofloxacin resistance was identified by detecting a mutation in gyrA and parC.
 Results: The biofilm intensity significantly decreased (P < 0.05) concerning S. aureus isolates and insignificantly (P > 0.05) concerning E. coli isolates. Yet, one E. coli isolate's biofilm was significantly decreased (P < 0.05) linearly with increasing eDNA. Of considerable interest, the addition of eDNA led to a significant increase (P < 0.05) in the biofilm of the two-tested P. aeruginosa isolates. Moreover, eDNA participated in transferring Ciprofloxacin resistance to the sensitive isolate when it presents in its biofilm.
 Conclusion: eDNA has a dual effect on bacterial biofilms either supportive or suppressive following bacterial species per se. Also, it seems to play an important role in antibiotic resistance within the biofilm.

Novel Keto-Alkyl-Pyridinium Antifungal Molecules Active in Models of In Vivo Candida albicans Vascular Catheter Infection and Ex Vivo Candida auris Skin Colonization.

New antifungal therapies are needed for both systemic, invasive infections in addition to superficial infections of mucosal and skin surfaces as well as biofilms associated with medical devices. The resistance of biofilm and biofilm-like growth phases of fungi contributes to the poor efficacy of systemic therapies to nonsystemic infections. Here, we describe the identification and characterization of a novel keto-alkyl-pyridinium scaffold with broad spectrum activity (2 to 16 μg/mL) against medically important yeasts and molds, including clinical isolates resistant to azoles and/or echinocandins. Furthermore, these keto-alkyl-pyridinium agents retain substantial activity against biofilm phase yeast and have direct activity against hyphal A. fumigatus. Although their toxicity precludes use in systemic infections, we found that the keto-alkyl-pyridinium molecules reduce Candida albicans fungal burden in a rat model of vascular catheter infection and reduce Candida auris colonization in a porcine ex vivo model. These initial preclinical data suggest that molecules of this class may warrant further study and development for nonsystemic applications.

Antifungal therapy of Candida biofilms: Past, present and future

Virtually all Candida species linked to clinical candidiasis are capable of forming highly resistant biofilms on different types of surfaces, which poses an additional significant threat and further complicates therapy of these infections. There is a scarcity of antifungal agents, and their effectiveness, particularly against biofilms, is limited. Here we provide a historical perspective on antifungal agents and therapy of Candida biofilms. As we reflect upon the past, consider the present, and look towards the future of antifungal therapy of Candida biofilms, we believe that there are reasons to remain optimistic, and that the major challenges of Candida biofilm therapy can be conquered within a reasonable timeframe.

Conformal Electrodeposition of Antimicrobial Hydrogels Formed by Self‐Assembled Peptide Amphiphiles

AbstractThe colonization of biomedical surfaces by bacterial biofilms is concerning because these microorganisms display higher antimicrobial resistance in biofilms than in liquid cultures. Developing antimicrobial coatings that can be easily applied to medically‐relevant complex‐shaped objects, such as implants and surgical instruments, is an important and challenging research direction. This work reports the preparation of antibacterial surfaces via the electrodeposition of a conformal hydrogel of self‐assembling cationic peptide‐amphiphiles (PAs). Hydrogels of three PAs are electrodeposited: C16K2, C16K3, and C18K2, where Cn is an alkyl chain of n methylene groups and Km is an oligopeptide of m lysines. The processing variables (electrodeposition time, potential, pH, salt concentration, agitation) enable fine control of film thickness, demonstrating the flexibility of the method and allowing to unravel the mechanisms underlying electrodeposition. The electrochemically prepared hydrogels inhibit the growth of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa in agar plates, and prevent the formation of biofilms of Acinetobacter baumannii and P. aeruginosa and the formation of A. baumannii colonies in solid media. C16K2 and C16K3 hydrogels outperform the antimicrobial activity of those of C18K2 while maintaining good compatibility with human cells.

Heterogeneous distribution of carbofuran shaped by Pseudomonas stutzeri biofilms enhances biodegradation of agrochemicals

Biodegradation, harnessing the metabolic versatility of microorganisms to reduce agrochemical contaminations, is commonly studied with enriched planktonic cells but overlooking the dominant lifestyle of microorganisms is to form biofilms, which compromises the efficiency of biodegradation in natural environment. Here, we employed a carbofuran-degrading bacterium Pseudomonas stutzeri PS21 to investigate how the bacterial biofilms formed and responded to agrochemicals. First, the PS21 biofilms formed with a core of bacterial cells enclosing with extracellular polymeric substances (EPSs), and the biofilms were active and resilient when exposed to carbofuran (up to 50 mg L−1). The formation was regulated by the second messenger bis-(3′-5′)-cyclic di-guanosine monophosphate signaling, which strengthened the structural resistance and metabolic basis of biofilms to remain the degrading efficiency as comparable as the planktonic cells. Second, carbofuran distributed heterogeneously in the near-biofilm microenvironment via the covalent adsorption of biofilms, which provided a spontaneous force that enhanced the combination of carbofuran with biofilms to maintain high degrading activity. Additionally, we elucidated the biodegradation was driven by the integrated metabolic system of biofilms involving the extracellular enzymes located in the EPSs. This study exhibited the structural and metabolic advantages of microbial biofilms, highlighting the attractive potentials of exploring biofilm-based strategies to facilitate the in-situ bioremediation of organic contaminations.

CHARACTERIZATION OF A NOVEL ANTIMICROBIAL SOL-GEL DEVICE COATING TO PREVENT PERIPROSTHETIC JOINT INFECTION

An increasing elderly population means joint replacement surgery numbers are projected to increase, with associated complications such as periprosthetic joint infections (PJI) also rising. PJI are particularly challenging due to antimicrobial resistant biofilm development on implant surfaces and surrounding tissues, with treatment typically involving invasive surgeries and systemic antibiotic delivery. Consequently, functionalisation of implant surfaces to prevent biofilm formation is a major research focus. This study characterises clinically relevant antimicrobials including gentamicin, clindamycin, daptomycin, vancomycin and caspofungin within a silica-based, biodegradable sol-gel coating for prosthetic devices.Antimicrobial activity of the coatings against clinically relevant microorganisms was assessed via disc diffusion assays, broth microdilution culture methods and the MBEC assay used to determine anti-biofilm activity. Human and bovine cells were cultured in presence of antimicrobial sol-gel to determine cytotoxicity using Alamar blue and antibiotic release was measured by LC-MS. Biodegradability in physiological conditions was assayed by FT-IR, ICP-MS and measuring mass change. Effect of degradation products on osteogenesis were studied by culturing mesenchymal stem cells in the presence of media in which sol-gel samples had been immersed.Antimicrobial-loaded coatings showed strong activity against a wide range of clinically relevant bacterial and fungal pathogens with no loss of activity from antibiotic alone. The sol-gel coating demonstrated controlled release of antimicrobials and initial sol-gel coatings showed no loss of viability on MSCs with gentamicin containing coatings. Current work is underway investigating cytotoxicity of sol-gel compositions against MG-63 cells and primary osteoblasts.This research forms part of an extended study into a promising antimicrobial delivery strategy to prevent PJI. The implant coating has potential to advance PJI infection prevention, reducing future burden upon healthcare costs and patient wellbeing.

Inhibition of Mixed Biofilms of Candida albicans and Staphylococcus aureus by β-Caryophyllene-Gold Nanoparticles.

Polymicrobial biofilms, consisting of fungal and bacterial pathogens, often contribute to the failure of antimicrobial treatment. The growing resistance of pathogenic polymicrobial biofilms to antibiotics has led to the development of alternative strategies to combat polymicrobial diseases. To this end, nanoparticles synthesized using natural molecules have received significant attention for disease treatment. Here, gold nanoparticles (AuNPs) were synthesized using β-caryophyllene, a bioactive compound isolated from various plant species. The shape, size, and zeta potential of the synthesized β-c-AuNPs were found to be non-spherical, 17.6 ± 1.2 nm, and -31.76 ± 0.73 mV, respectively. A mixed biofilm of Candida albicans and Staphylococcus aureus was used to test the efficacy of the synthesized β-c-AuNPs. The results revealed a concentration-dependent inhibition of the initial stages of formation of single-species as well as mixed biofilms. Furthermore, β-c-AuNPs also eliminated mature biofilms. Therefore, using β-c-AuNPs to inhibit biofilm and eradicate bacterial-fungal mixed biofilms represents a promising therapeutic approach for controlling polymicrobial infections.

Molecular characterization and comparative genomic analysis of Acinetobacter baumannii isolated from the community and the hospital: an epidemiological study in Segamat, Malaysia.

Acinetobacter baumannii is a common cause of multidrug-resistant (MDR) nosocomial infections around the world. However, little is known about the persistence and dynamics of A. baumannii in a healthy community. This study investigated the role of the community as a prospective reservoir for A. baumannii and explored possible links between hospital and community isolates. A total of 12 independent A. baumannii strains were isolated from human faecal samples from the community in Segamat, Malaysia, in 2018 and 2019. Another 15 were obtained in 2020 from patients at the co-located tertiary public hospital. The antimicrobial resistance profile and biofilm formation ability were analysed, and the relatedness of community and hospital isolates was determined using whole-genome sequencing (WGS). Antibiotic profile analysis revealed that 12 out of 15 hospital isolates were MDR, but none of the community isolates were MDR. However, phylogenetic analysis based on single-nucleotide polymorphisms (SNPs) and a pangenome analysis of core genes showed clustering between four community and two hospital strains. Such clustering of strains from two different settings based on their genomes suggests that these strains could persist in both. WGS revealed 41 potential resistance genes on average in the hospital strains, but fewer (n=32) were detected in the community strains. In contrast, 68 virulence genes were commonly seen in strains from both sources. This study highlights the possible transmission threat to public health posed by virulent A. baumannii present in the gut of asymptomatic individuals in the community.

Application of a novel lytic Jerseyvirus phage LPSent1 for the biological control of the multidrug-resistant Salmonella Enteritidis in foods.

Non-typhoidal Salmonella is the tremendously predominant source of acquired foodborne infection in humans, causing salmonellosis which is a global threat to the healthcare system. This threat is even worse when it is combined with the incidence of multidrug-resistant Salmonella strains. Bacteriophage therapy has been proposed as a promising potential candidate to control a diversity of foodborne infective bacteria. The objective of this study designed to isolate and characterize lytic phages infecting zoonotic multi-drug resistant and strong biofilm producer Salmonella enterica serovar Enteritidis EG.SmE1 and then apply the isolated phage/s as a biocontrol agent against infections in ready-to-eat food articles including milk, water, apple juice, and chicken breasts. One lytic phage (LPSent1) was selected based on its robust and stable lytic activity. Phage LPSent1 belonged to the genus Jerseyvirus within the Jerseyvirinae subfamily. The lysis time of phage LPSent1 was 60 min with a latent period of 30 min and each infected cell burst about 112 plaque-forming units. Phage LPSent1 showed a narrow host range. Furthermore, the LPSent1 genome did not encode any virulence or lysogenic genes. In addition, phage LPSent1 had wide pH tolerance, prolonged thermal stability, and was stable in food articles lacking its susceptible host for 48 h. In vitro applications of phage LPSent1 inhibited free planktonic cells and biofilms of Salmonella Enteritidis EG.SmE1 with a lower occurrence to form phage-resistant bacterial mutants which suggests promising applications on food articles. Application of phage LPSent1 at multiplicities of infections of 100 or 1000 showed significant inhibition in the bacterial count of Salmonella Enteritidis EG.SmE1 by 5 log10/sample in milk, water, apple juice, and chicken breasts at either 4°C or 25°C. Accordingly, taken together these findings establish phage LPSent1 as an effective, promising candidate for the biocontrol of MDR Salmonella Enteritidis in ready-to-eat food.

Microplastic biofilm, associated pathogen and antimicrobial resistance dynamics through a wastewater treatment process incorporating a constructed wetland

Microplastics in wastewater are colonized by biofilms containing pathogens and antimicrobial resistance (AMR) genes that can be exported into receiving water bodies. This study investigated establishment and changes in microplastic-associated biofilm and AMR during a conventional full-scale 2100 population equivalent wastewater treatment process combined with a free water surface polishing constructed wetland. Sequential microplastic colonization experiments were conducted at different stages of the wastewater treatment process, including in raw sewage, treated effluent and the constructed wetland. Two scenarios were tested in which the constructed wetland served as either (i) a polishing step or (ii) as primary recipient of sewage inoculated microplastics. Bacterial 16S rRNA gene sequencing was carried out for qualitative bacterial community analysis. qPCR was applied for quantitative analysis of AMR genes (sul1, ermB, tetW, intiI1), bacterial biomass (16S rRNA) and a human fecal marker (HF183). Microbial diversity on microplastics increased with incubation time. The initial sewage-derived biofilm composition changed more significantly in the wastewater effluent compared to the constructed wetland. Pathogen and AMR load decreased by up to two orders of magnitude after coupled conventional and constructed wetland treatment, while less impact was observed when sewage-inoculated microplastic material was directly transferred into the constructed wetland. Aeromonas, Klebsiella, and Streptococcus were key pathogenic genera correlated with AMR in microplastic-associated biofilms. Despite decreasing trends on human pathogens and AMR load along the treatment process, microplastic-associated biofilms were a considerable potential hotspot for AMR (intI1 gene) and accommodated Cyanobacteria and fish pathogens.

Antibiotic‐Derived Carbon‐Nanodot‐Decorated Hydrogel for Reactive Oxygen Species‐Enhanced Anti‐Infection Through Biofilm Damage

AbstractIrreversible bacterial resistance and impenetrable biofilms have rendered conventional antibiotic therapy ineffective. Nevertheless, increasing evidence has confirmed that antibiotic carbon nanodots (CDs) exhibit potent antibacterial activity. However, the complex chemical composition of antibiotic CDs, and, hence, their antibacterial mechanism, is difficult to understand. The design of new antibiotic CDs against antibacterial resistance is an urgent requirement.In this study, kanamycin‐sulfate‐derived carbon nanodots (KCDs) are found to exhibit significant antibacterial potential with the assistance of light irradiation. Systematic analysis indicates that KCDs not only retain the active structure of kanamycin but also produce five new components modified on its surface, which are shown to inhibit the activity of Staphylococcus aureus beta‐ketoacyl‐acp synthase III (FabH) through molecular docking. Furthermore, the multifunctional hydrogels (CG‐KCDs) self‐assemble into injectable, self‐healing, and antibiofilm structures through noncovalent forces between the KCDs and cationic guar gum (CG). The results indicate that under laser, CG‐KCDs irradiation exhibits enhanced antibacterial activity in vitro by damaging bacterial biofilms in a reactive oxygen species (ROS)‐dependent manner, as determined by transcriptomics. Further, the therapeutic effects of CG‐KCDs hydrogel dressings on wound healing and tissue remodeling under laser are confirmed using an in vivo wound infection model. These results validate the potential of KCDs as efficient antibacterial agents to replace antibiotics as an anti‐infective strategy.

Antimicrobials from Medicinal Plants: Key Examples, Success Stories and Prospects in Tackling Antibiotic Resistance

Abstract: The rising statistics of antimicrobial resistance pose an alarming concern for the mankind. The extensive/injudicious use of antibiotics in the environment, animal husbandry, and health care have led to the alarming rise of infectious microbes developing resistance against conventional drugs. The use of phytotherapeutics defines an attractive approach to tackling drug-resistant microbes, attributed to their ability to target major antimicrobial resistance mechanisms, including efflux pumps, biofilms, and cell membranes, among others. In recent times, the discovery and bioprospection of plants for value-added metabolites have witnessed a tremendous upsurge, with several phytomolecules demonstrating bactericidal and drug-resistance reversal properties. However, several existing challenges, including their low concentration in plants, climatic variations, overutilization of plant resources, and deforestation, have limited the utilization of phytotherapeutics. Discussing the growing concern of drug-resistant microbes and antimicrobial resistance, the thematic article discusses the existing and emerging scenarios of antimicrobial resistance in microbes. In the post-antibiotic era, phytotherapeutics defines enormous potential to tackle the growing threat of antimicrobial resistance, addressed through genetic engineering of microbes/plant systems for enhanced antimicrobial production. The success stories of antimicrobials from medicinal plants, as exemplified by key examples, associated challenges, possible strategies, and prospects of antimicrobials in drug discovery, form the key underlying theme of the article.

An Innovative Waterwheel-Rotating Biological Contactor (WRBC) System for Rural Sewage Treatment

The treatment of rural sewage has become an important part of environmental protection. In this study, a novel waterwheel-rotating biological contactor (WRBC) system, with intensified biofilm and high-shock load resistance, was applied to treat rural sewage. When the COD concentration of actual sewage fluctuated between 79–530 mg/L, the COD removal efficiency was 41.3–94.5%, and the NH4+-N removal efficiency always reach 100% with actual sewage. The TN removal efficiency changed between 14.3–86.2%, which was greatly affected by the water intake. The effluent TN concentration ranged from 5 to 14 mg/L, which meets the emission requirements. It maintained an absolute effluent stability when the change rates of influent loads (N or COD) varied from −60% to 100%. The biofilm morphology and the composition of extracellular polymeric substances were evaluated based on SEM and FTIR spectra. The results showed that the -NH2 group content increased compared with the inoculated sludge, and the biofilm formed more uneven compact clusters after the treatment of actual sewage. Based on 16SrRNA high-throughput sequencing techniques, the bacterial diversity and microbial community structure of the WRBC system over time was revealed. This study may help guide optimization strategies for more effective pollutant removal in rural areas.

Effect of Vapor-Phase Oregano Essential Oil on Resistant Candida Species Biofilms: Mechanisms of Action.

Vulvovaginal candidiasis (VVC) is one of the most prevalent vaginal infectious diseases. The increasing incidence of drug-resistant Candida strains and the limited therapeutic options make the discovery of effective alternative therapies fundamental. Essential oils (EOs) have been suggested as a promising alternative, and interestingly, vapor-phase essential oils (VP-EOs) present more advantages than their direct application. Thus, this study aims to evaluate the effect of oregano VP-EO (VP-OEO) on biofilms of antifungal-resistant vaginal isolates of Candida species (Candida albicans and Candida glabrata) and determine its mode of action. CFU, membrane integrity, and metabolic activity were evaluated. Furthermore, a reconstituted vaginal epithelium was used to mimic vaginal conditions and evaluate the effect of VP-OEO on Candida species infection, analyzed by DNA quantification, microscopy, and lactate dehydrogenase activity. The results revealed high VP-OEO antifungal activity. There was a significant reduction (>4 log CFU) in Candida species biofilms. Furthermore, the results show that the mechanisms of action of VP-OEO are related to membrane integrity and metabolic activity. The epithelium model confirms the effectiveness of VP-OEO. This study suggests that VP-EO can be considered a first approach for the development of an alternative form of VVC treatment. IMPORTANCE This work presents a new approach to the application of essential oils, exposure to the vapor phase, which can be considered a first approach for the development of a complementary or alternative form of vulvovaginal candidiasis (VVC) treatment. VVC is a significant infection caused by Candida species and remains a common disease that affects millions of women every year. The great difficulty in treating VVC and the extremely limited effective therapeutic options make the development of alternative treatments crucial. In this scope, this study aims to contribute to the development of effective, inexpensive, and nontoxic strategies for the prevention and treatment of this infectious disease, based on natural products. Moreover, this new approach has several advantages for women, such as lower costs, easy access, an easier mode of application, avoidance of skin contact, and, therefore, fewer negative impacts on women's health.

Community-specific diffusion characteristics determine resistance of biofilms to oxidative stress

Biofilms are multicellular communities with a spatial structure. Different from single-cell scale diffusion in planktonic systems, the diffusion distance becomes the dimension of multicellular clusters in a biofilm. Such differences in diffusion behavior affect the tolerance and response to exogenous stress. Here, we found that at the same doses of exogenous hydrogen peroxide (H2O2), planktonic Escherichia coli were completely killed within twohours, whereas the biofilm resumed growth in sixhours by building a catalase barrier to block H2O2 penetration, despite the growth burden. Unexpectedly, when we changed the carbon source from glucose to glycerol, H2O2 instantly counterintuitively boosted biofilm growth due to supplemental oxygen, which was the growth-limiting factor. We further demonstrated that the energy metabolism modes determined the growth-limiting factor, which then determined the two patterns of biofilms resistances to H2O2.

Antibiotic resistance and biofilm forming abilities of Listeria monocytogenes and effect of subMIC concentration of white vinegar on these virulence factors

AbstractIn the present study, antibiotic resistance profiles and biofilm forming abilities of 9 Listeria monocytogenes isolates obtained from out of 30 retail meat samples were determined, and the effect of commercial white vinegar on these virulence factors in isolates exposed to subMIC concentrations were investigated. All isolates were found to be resistant to cefotixin and oxacillin, 8 isolates (26.6%) to clindamycin, 1 isolate (3.3%) to rifampicin, and 1 (3.3%) isolate was found to show intermediate resistance against clindamycin. Biofilm formation was determined for all the isolates at 22 °C and 37 °C (24 h, 48 h and 72 h). MIC values of white vinegar samples were determined at 3.12% for all isolates. MIC/2 and MIC/4 concentrations of white vinegar increased the biofilm forming capacity of the isolates by 21.2% and 17.1%, respectively. After exposure to MIC/2 concentration of white vinegar for seven days, the antibiotic resistance status of the isolates to tetracycline, rifampicin, and clindamycin changed, and the biofilm forming abilities significantly decreased at 4 °C and 37 °C for 48 h and at 37 °C for 72 h (P < 0.05). The results showed that the use of subMIC concentrations of white vinegar should be avoided in routine sanitation applications.

Candida-Candida and Candida-Staphylococcus species interactions in in-vitro dual-species biofilms

Objective: In present study, interaction between different Candida species and also their interaction with Staphylococcus species were investigated in mono and dual-species biofilm model. Methods: Resistant and weak biofilms former Candida(C. albicans, C. glabrata, C. krusi) and Staphylococcus species (S. aureus, S. epidermidis, S. saprophyticus) alongwith ATCC isolates were used in mono and different dual-species combinations for estimation of biofilms by crystal violet (CV) biofilm biomass assay and XTT reduction assay. Aspartyl proteinase activity of Candida species was also measured in these developed biofilms. Results: CV assay showed increased in biofilm biomass after 48 h of incubation in developed mono and dual-species biofilms. XTT reduction assay showed overall decreasing trend in metabolic rate in biofilms after 48 h of incubation. All three Candida species with each other in dual-species in-vitro biofilms showed antagonistic behaviour. Biofilm biomass production was raised for C. albicans and C. glabrata dual-specie biofilm with allStaphylococcus species except with clinical isolate of S. aureus and in C. glabrata-S. epidermidis dual-specie biofilm. ATCC and clinical isolate of Candida showed markedly decrease aspartyle proteinase activity when co-cultured withStaphylococcuscompared to when it was cultured alone.

Intermittent antibiotic treatment of bacterial biofilms favors the rapid evolution of resistance

Bacterial antibiotic resistance is a global health concern of increasing importance and intensive study. Although biofilms are a common source of infections in clinical settings, little is known about the development of antibiotic resistance within biofilms. Here, we use experimental evolution to compare selection of resistance mutations in planktonic and biofilm Escherichia coli populations exposed to clinically relevant cycles of lethal treatment with the aminoglycoside amikacin. Consistently, mutations in sbmA, encoding an inner membrane peptide transporter, and fusA, encoding the essential elongation factor G, are rapidly selected in biofilms, but not in planktonic cells. This is due to a combination of enhanced mutation rate, increased adhesion capacity and protective biofilm-associated tolerance. These results show that the biofilm environment favors rapid evolution of resistance and provide new insights into the dynamic evolution of antibiotic resistance in biofilms.

Effect of Sodium Hypochlorite on Biofilm-Producing Organisms Isolated from A Hospital Drinking Water

Objectives: Providing safe drinking water is essential for maintaining healthcare quality. The presence of biofilms in the water supply protects the organism from the antimicrobial effects of disinfectants leading to the formation of the MDR pathogen pool. Therefore, this study was taken up to determine the prevalence of biofilm formation in the bacteria isolated from the water system of a tertiary health care setup and study the effect of disinfectants on biofilms.
 Methods: Thirty-four drinking water samples were collected in sterile glass stopper bottles and transported to the lab. Standard bacteriological procedures identified isolates. Biofilm detection was carried out by the tissue culture plate (TCP) method. The effect of disinfectant (sodium hypochlorite) at various concentrations (0, 0.25, 0.5, 1, 2, and 4 %) on biofilm-producing organism were studied for 30 minutes and analyzed.
 Results: The culture positivity was 76.4% (26/34). Twenty samples showed monomicrobial growth, while only six samples showed polymicrobial growth of organisms. The most common organism isolated was Pseudomonas aeruginosa. Biofilm production was seen more in polymicrobial organisms, 91.66 % (11/12). A high level of resistance to chlorine compounds was seen in biofilm-producing microorganisms, especially those that produced robust biofilms.
 Conclusion: Resistance of biofilms against high levels of chlorine has implications for the delivery of safe drinking water. Drug resistance was seen in these organisms, which can be transmitted from drinking water sources to humans. Therefore, it is recommended that biofilm production should be evaluated in drinking water samples regularly..J Microbiol Infect Dis 2022; 12(4):17-24.