Biofilm-producing Strains Research Articles

Antibacterial and Antibiofilm Activity of Juglone Derivatives against Enterococcus faecalis: An In Silico and In Vitro Approach.

Enterococcus faecalis is a Gram-positive bacterium that is normally found in the gastrointestinal tract of humans and animals. E. faecalis is an opportunistic pathogen that causes a number of invasive and noninvasive infections. The emergence of multidrug resistance and biofilm formation by the bacterium have rendered the treatment of E. faecalis infections very difficult. Due its high rate of resistance and biofilm formation, there are very few options of treatment. Therefore, the current study was designed to evaluate the antibacterial and biofilm activities of juglone derivatives such as 2-methoxy-6-acetyl-7-methyljuglone and 2-ethoxy-6-acetyl-7-methyljuglone against multidrug-resistant (MDR) and biofilm-producing strains of E. faecalis. Agar well diffusion and broth microdilution methods were used to determine the antibacterial activities. Biofilm attachment and preformed biofilm inhibition were determined using crystal violet staining assay. Both juglone derivatives displayed promising antibacterial and antibiofilm activities against E. faecalis. Among these compounds, 2-ethoxy-6-acetyl-7-methyljuglone possessed better inhibitory activity with minimum inhibitory concentration (MIC) of 9.7 ± 3 μM as compared to 2-methoxy-6-acetyl-7-methyljuglone (MIC, 19.5 ± 2 μM). Additionally, 2-ethoxy-6-acetyl-7-methyljuglone also showed stronger antibiofilm activity than 2-methoxy-6-acetyl-7-methyljuglone. Furthermore, both the ligand molecules were docked into the binding site of the enterococcal surface protein, and the results revealed that both the molecules are actively binding in the target site. Based on these findings, juglone derivatives may be considered useful for the treatment of E. faecalis infections; however, further studies are required to elucidate the mechanism of action.

Evaluation of antibacterial activity of five biocides and the synergistic effect of biocide/EDTA combinations on biofilm-producing and non-producing Stenotrophomonas maltophilia strains isolated from clinical specimens in Iran

BackgroundThe overuse of biocides in healthcare-facilities poses risk for emergence and spread of antibiotic resistance among nosocomial pathogens. Hospital-acquired infections due to S. maltophilia have been increased in the recent years and with its various resistance mechanisms contribute to patient morbidity and mortality in hospitals. The current study aimed to evaluate the susceptibility of biofilm-producing and non-producing S. maltophilia clinical isolates to five commonly used hospital biocides, alone and in combination with EDTA to examine the synergistic effect of combining EDTA on the bactericidal activity of them by microbroth dilution method. As well as the frequency of efflux genes encoding resistance to biocides among isolates. This study also intended to assess the effect of exposure of S. maltophilia isolates to sub-inhibitory concentrations of sodium hypochlorite upon the antimicrobial susceptibility patterns.ResultsBased on minimum inhibitory and bactericidal concentrations of biocides sodium hypochlorite 5% (w/v) and ethyl alcohol 70% (v/v) were the strongest and weakest biocides against S. maltophilia isolates, respectively. The combination of EDTA with biocides significantly increased the effectiveness of the studied biocides. Exposure to sub-inhibitory concentration of sodium hypochlorite showed a significant change in the susceptibility of isolates towards ceftazidime (p = 0.019), ticarcillin/clavulanate (p = 0.009), and chloramphenicol (p = 0.028). As well as among the isolates examined, 94 (95%) were able to produce biofilm. The frequency of sugE1 resistance genes was found in 90.7% of our clinical S. maltophilia isolates. None of the isolates carried qacE and qacEΔ1 gene.ConclusionsThe current study recommended that using the mixture of biocides with EDTA can be effective in reducing nosocomial infections. Also, this study demonstrated that exposure to sub-inhibitory concentrations of sodium hypochlorite leads to reduced antibiotic susceptibility and development of multidrug-resistant S. maltophilia strains.

Biofilms and efflux pump regulatory gene (mexR) in multidrug-resistant Pseudomonas aeruginosa isolated from migratory birds in Egypt.

Multidrug-resistant (MDR) Pseudomonas aeruginosa is a global threat to public health. This study aimed to determine biofilms and efflux pump regulatory gene (mexR) in MDR P. aeruginosa isolates. A total of 42 fecal samples of aquatic migratory birds collected during hunting season in Egypt were evaluated for the detection of P. aeruginosa according to standard culture-based methods. The antibiotic susceptibility of P. aeruginosa strains was evaluated using disk diffusion methods. The biofilm formation ability of the isolates was phenotypically determined using a colorimetric microtitration plate assay. Polymerase chain reaction amplification was performed to detect biofilm genes (PelA and PslA) and mexR. In total, 19 isolates (45.2%) were recovered from the 42 fecal samples of migratory birds. All isolates were identified as MDR P. aeruginosa, and 78.9% of the strains produced biofilms at different degrees. Molecular detection of biofilm extracellular polymeric substances revealed that PelA was the most predominant gene in the biofilm-producing isolates, followed by PslA. mexR was detected in 63.2% of MDR P. aeruginosa isolates, and its prevalence was higher in non-biofilm-producing strains (75%) than in biofilm-producing strains (60%). Antibiotic resistance in P. aeruginosa isolates recovered from migratory birds through various mechanisms is a major public and animal health problem. It is important to consider the significance of migratory birds in disease transmission.

In Vitro and In Vivo Antimicrobial Activity of Hypochlorous Acid against Drug-Resistant and Biofilm-Producing Strains.

ABSTRACTThe aims of this study were as follows. First, we determined the antimicrobial efficacy of hypochlorous acid (HClO) against bacterial, fungal, and yeast strains growing planktonically and growing in biofilms. Second, we sought to compare the activity of the combination of daptomycin and HClO versus those of the antimicrobial agents alone for the treatment of experimental catheter-related Staphylococcus epidermidis infection (CRI) using the antibiotic lock technique (ALT) in a rabbit model. HClO was generated through direct electric current (DC) shots at determined amperages and times. For planktonic susceptibility studies, 1 to 3 DC shots of 2, 5, and 10 mA from 0 to 300 s were applied. A DC shot of 20 mA from 0 to 20 min was applied to biofilm-producing strains. Central venous catheters were inserted into New Zealand White rabbits, inoculated with an S. epidermidis strain, and treated with saline solution or ALT using daptomycin (50 mg/mL), HClO (20 mA for 45 min), or daptomycin plus HClO. One hundred percent of the planktonic bacterial, fungal, and yeast strains were killed by applying one DC shot of 2, 5, and 10 mA, respectively. One DC shot of 20 mA for 20 min was sufficient to eradicate 100% of the tested biofilm-producing strains. Daptomycin plus HClO lock therapy showed the highest activity for experimental CRI with S. epidermidis. HClO could be an effective strategy for treating infections caused by extensively drug-resistant or multidrug-resistant and biofilm-producing strains in medical devices and chronic wounds. The results of the ALT using daptomycin plus HClO may be promising.IMPORTANCE Currently, drug-resistant infections are increasing and there are fewer antibiotics available to treat them. Therefore, there is an urgent need to find new antibiotics and nonantimicrobial strategies to treat these infections. We present a new nonantibiotic strategy based on hypochlorous acid generation to treat long-term catheter-related and chronic wounds infections.

Analysis of biofilm production and expression of adhesion structures of circulating Clostridioides difficile strains from Mexico

IntroductionClostridioides difficile biofilms are believed to protect the pathogen from antibiotics, in addition to potentially contributing to recurrent infections. MethodologyBiofilm production of 102 C. difficile isolates was determined using the crystal violet staining technique, and detachment assays were performed. The expression levels of cwp84 and slpA genes were evaluated by real-time PCR on selected isolates. ResultsMore than 70% of isolates (75/102) were strong biofilm producers, and the highest detachment of biofilm was achieved with the proteinase K treatment (>90%). The overall mean expression of cwp84 was higher in RT027 than in RT001 (p=0.003); among strong biofilm-producing strains, the slpA expression was lower in RT027 than in RT001 (p<0.000). ConclusionsProteins seem to have an important role in the biofilm's initial adherence and maturation. slpA and cwp84 are differentially expressed by C. difficile ribotype and biofilm production level.

Isolation and Molecular Detection of Enterococcus faecalis from Cow Milk of Anand City with Special Reference to

The present study was conducted to determine the drug resistance pattern and the occurrence of biofilm-producing Enterococcus faecalis from cow milk samples collected from in and around Anand city, Gujarat. A total of 100 samples were collected aseptically from the doorsteps of livestock farmers. Out of 100 samples, 73 (73%) samples were found to be positive on selective media, which was confirmed by polymerase chain reaction, which revealed that all the 73 isolates were of Enterococcus faecalis. The antibiotic sensitivity test showed that all the isolates were sensitive to ampicillin (100%) only, and resistance was observed against Trimethoprim (100%), Tigecycline (80.82%), Vancomycin (67.12%), Gentamicin (46.57%), Imipenem-cilastatin (28.76%), and Norfloxacin (10.95%). Out of all the positive isolates, 30.13% (22/73) were biofilm producers. So, it can be concluded that milk can be a possible intermediary vehicle for the spread of multidrug-resistant biofilm-producing enterococci strains to humans

Analysis of Microorganism Colonization, Biofilm Production, and Antibacterial Susceptibility in Recurrent Tonsillitis and Peritonsillar Abscess Patients.

Background: Despite the widespread use of antibiotics to treat infected tonsils, episodes of tonsillitis tend to recur and turn into recurrent tonsillitis (RT) or are complicated by peritonsillar abscesses (PTAs). The treatment of RT and PTAs remains surgical, and tonsillectomies are still relevant. Materials and methods: In a prospective, controlled study, we analyzed the bacteria of the tonsillar crypts of 99 patients with RT and 29 patients with a PTA. We performed the biofilm formation and antibacterial susceptibility testing of strains isolated from study patients. We compared the results obtained between patient groups with the aim to identify any differences that may contribute to ongoing symptoms of RT or that may play a role in developing PTAs. Results: The greatest diversity of microorganisms was found in patients with RT. Gram-positive bacteria were predominant in both groups. Candida species were predominant in patients with a PTA (48.3% of cases). Irrespective of patient group, the most commonly isolated pathogenic bacterium was S. aureus (in 33.3% of RT cases and in 24.14% of PTA cases). The most prevalent Gram-negative bacterium was K. pneumoniae (in 10.1% of RT cases and in 13.4% of PTA cases). At least one biofilm-producing strain was found in 37.4% of RT cases and in 27.6% of PTA cases. Moderate or strong biofilm producers were detected in 16 out of 37 cases of RT and in 2 out of 8 PTA cases. There was a statistically significant association found between the presence of Gram-positive bacteria and a biofilm-formation phenotype in the RT group and PTA group (Pearson χ2 test, p < 0.001). S. aureus and K. pneumoniae strains were sensitive to commonly used antibiotics. One S. aureus isolate was identified as MRSA. Conclusions: S. aureus is the most common pathogen isolated from patients with RT, and Candida spp. are the most common pathogens isolated from patients with a PTA. S. aureus isolates are susceptible to most antibiotics. Patients with RT more commonly have biofilm-producing strains, but patients with a PTA more commonly have biofilm non-producer strains. K. pneumoniae does not play a major role in biofilm production.

Determination of Enterococcal Virulence Factors Expression and Impact of Biofilm Formation on Antimicrobial Susceptibility Pattern

Introduction: Enterococcus spp. has become recognized as a significant cause of hospital-acquired infections. Two main virulence factors namely gelatinase and hemolysin of Enterococci have been proved to cause severe infections. In addition, biofilm formation is causing infection by enhancing the persistence of Enterococci in medical indwelling devices. Therefore, the study aimed to evaluate the presence of hemolysin, gelatinase, and biofilm formation in Enterococcus spp. and the impact of biofilm on antimicrobial susceptibility patterns.&#x0D; Materials &amp; Methods: Total 104 Enterococcal isolates obtained from different clinical samples were included in the study for expression of virulence factors. All isolates were evaluated for biofilm formation by the tissue culture plate method. Hemolysin production was checked by using 5% sheep blood agar and gelatinase production by peptone yeast extract agar containing 3% gelatin. Antimicrobial susceptibility testing was done by the Vitek2 compact automated system.&#x0D; Results: Out of 104 isolates, 1(1%) were strong biofilm producers while 4(3.85% %) and 54(52%) were moderate and weak biofilm producers respectively. Hemolysin production was observed in 19(18%) isolates and gelatinase production was universal.&#x0D; Conclusion: Biofilm-producing strains showed higher resistance to beta-lactam drugs and high-level aminoglycosides. Hence, amongst three virulence factors, studying biofilm formation can be an important tool to develop a hospital’s antibiotic policy and other virulence factors can be helpful to understand the pathogenesis of infection caused by Enterococcus spp. as well as for antimicrobial usage strategies.

Burkholderia pseudomallei biofilm phenotypes confined but surviving in neutrophil extracellular traps of varying appearance.

Melioidosis is a fatal infectious disease caused by Burkholderia pseudomallei. Complications following treatment are usually due to antibiotic resistance and relapse is mainly caused by B. pseudomallei biofilm. Although the release of neutrophil extracellular traps (NETs) is crucial to capture and eliminate bacterial pathogens, to date response of NETs to B. pseudomallei biofilm is poorly understood. Here we compare the NETs produced by neutrophils in response to B. pseudomallei H777 (a biofilm-producing strain containing the bpsl0618 gene), a biofilm-defect strain lacking this gene (B. pseudomallei M10) and a bpsl0618 biofilm-complemented strain, B. pseudomallei C17, in which function of bpsl0618 was restored. Co-cultivation of these strains with healthy human neutrophils at MOI 10 with or without cytochalasin D demonstrated that H777 significantly resisted neutrophil-mediated killing and non-phagocytotic mechanisms compared to M10 (p < 0.0001). Three distinct morphotypes of NETs were seen: "aggregated", "spiky" and "cloudy". These were induced in different proportions by the different bacterial strains. All types of NETs were shown to confine all B. pseudomallei strains. Strains H777 and C17 could stimulate production of twice as much extracellular DNA (234.62 ng/mL and 205.43 ng/mL, respectively) as did M10 (111.87 ng/mL). Cells of H777 and C17 were better able to survive in the presence of neutrophil killing mechanisms relative to M10 (p < 0.0001) and NET formation (p < 0.0001 and 0.05). These findings suggest that NET stimulation was insufficient to eradicate B. pseudomallei H777 and C17 despite their possession of bpsl0618, a sugar-transferase gene associated with biofilm formation ability. Our findings demonstrate that B. pseudomallei biofilm phenotype may be a key factor in assisting pathogens to escape killing by neutrophils. This work provides a better understanding of how B. pseudomallei biofilm-associated infections induce and survive NET formation, resulting in bacterial persistence and increased severity of disease.

Synergistic Activity of the Human Lactoferricin-Derived Peptide hLF1-11 in Combination with Caspofungin against Candida Species.

ABSTRACTCandida species are the main fungal opportunistic pathogens causing systemic infections that are often associated with drug resistance and biofilm production on medical devices. The pressing need for new antifungal agents led to an increased interest in the use of combination therapies. The present study was aimed at investigating potential synergistic activity of the human lactoferrin-derived hLF1-11 peptide with caspofungin against caspofungin-resistant or -susceptible C. albicans, C. parapsilosis, and C. glabrata strains. Synergism was evaluated by the checkerboard assay, measuring cellular metabolic activity against Candida planktonic and sessile cells. A fractional inhibitory concentration (FIC) index of ≤0.5 was interpreted as synergy. Synergism was evaluated by killing assays on planktonic cells. A cell viability assay was performed with biofilm formation inhibition and preformed biofilm. Synergy for killing and viability assays was defined as a ≥2-log-CFU/mL reduction in comparison with the most active constituent. hLF1-11 and caspofungin exerted (i) synergistic effects against planktonic cells of all the tested strains, yielding drastic caspofungin MIC reduction, (ii) synergistic effects on the inhibition of biofilm formation against biofilm producer strains, yielding caspofungin BIC reduction, and (iii) synergistic effects on preformed biofilm assessed by measuring metabolic activity (FIC range, 0.28 to 0.37) against biofilm-producing strains and by cell viability assay in C. albicans SC5314. The synergistic effect observed between caspofungin and hLF1-11 against Candida spp. is of potential clinical relevance, representing a promising novel approach to target caspofungin-resistant Candida species infections. Further studies elucidating the mechanisms of action of such a synergistic effect are needed.IMPORTANCE The present study describes a synergistic effect between a conventional antifungal drug, caspofungin, and a synthetic peptide derived from human lactoferrin, hLF1-11, against Candida species. These yeasts are able to cause severe systemic fungal infections in immunocompromised hosts. In addition, they can form biofilms in medical implanted devices. Recently, caspofungin-resistant Candida strains have emerged, thus highlighting the need to develop different therapeutic strategies. In in vitro studies, this drug combination is able to restore sensitivity to caspofungin in caspofungin-resistant strains of Candida species, both in free-living cells and in cells organized in biofilms. This synergism could represent a promising novel approach to target infections caused by caspofungin-resistant Candida species.

Photocatalyst-mineralized biofilms as living bio-abiotic interfaces for single enzyme to whole-cell photocatalytic applications.

There is an increasing trend of combining living cells with inorganic semiconductors to construct semi-artificial photosynthesis systems. Creating a robust and benign bio-abiotic interface is key to the success of such solar-to-chemical conversions but often faces a variety of challenges, including biocompatibility and the susceptibility of cell membrane to high-energy damage arising from direct interfacial contact. Here, we report living mineralized biofilms as an ultrastable and biocompatible bio-abiotic interface to implement single enzyme to whole-cell photocatalytic applications. These photocatalyst-mineralized biofilms exhibited efficient photoelectrical responses and were further exploited for diverse photocatalytic reaction systems including a whole-cell photocatalytic CO2 reduction system enabled by the same biofilm-producing strain. Segregated from the extracellularly mineralized semiconductors, the bacteria remained alive even after 5 cycles of photocatalytic NADH regeneration reactions, and the biofilms could be easily regenerated. Our work thus demonstrates the construction of biocompatible interfaces using biofilm matrices and establishes proof of concept for future sustainable photocatalytic applications.

Role of Extracellular DNA in Dalbavancin Activity against Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilms in Patients with Skin and Soft Tissue Infections.

ABSTRACTMethicillin-resistant Staphylococcus aureus (MRSA) has become the leading cause of skin and soft tissue infections (SSTIs). Biofilm production further complicates patient treatment, contributing to increased bacterial persistence and antibiotic tolerance. The study aimed to explore the efficacy of different antibiotics on biofilm-producing MRSA isolated from patients with SSTI. A total of 32 MRSA strains were collected from patients with SSTI. The MIC and minimal biofilm eradication concentration (MBEC) were measured in planktonic and biofilm growth. The study showed that dalbavancin, linezolid, and vancomycin all inhibited MRSA growth at their EUCAST susceptible breakpoint. Of the MRSA strains, 87.5% (n = 28) were strong biofilm producers (SBPs), while only 12.5% (n = 4) were weak biofilm producers (WBPs). The MBEC90 values for dalbavancin were significantly lower than those of linezolid and vancomycin in all tested strains. We also found that extracellular DNA (eDNA) contributes to the initial microbial attachment and biofilm formation. The amount of eDNA differed among MRSA strains and was significantly higher in those isolates with high dalbavancin and vancomycin tolerance. Exogenously added DNA increased the MBEC90 and protection of biofilm cells from dalbavancin activity. Of note, the relative abundance of eDNA was higher in MRSA biofilms exposed to MBEC90 dalbavancin than in untreated MRSA biofilms and those exposed to sub-MIC90. Overall, dalbavancin was the most active antibiotic against MRSA biofilms at concentrations achievable in the human serum. Moreover, the evidence of a drug-related increase of eDNA and its contribution to antimicrobial drug tolerance reveals novel potential targets for antibiofilm strategies against MRSA.IMPORTANCE Staphylococcus aureus is the most common cause of skin and soft tissue infections (SSTIs) worldwide. In addition, methicillin-resistant S. aureus (MRSA) is increasingly frequent in postoperative infections and responsible for a large number of hospital readmissions and deaths. Biofilm formation by S. aureus is a primary risk factor in SSTIs, due to a higher antibiotic tolerance. Our study showed that the biofilm-forming capacity varied among MRSA strains, although strong biofilm producers were significantly more abundant than weak biofilm producer strains. Notably, dalbavancin demonstrated a potent antibiofilm activity at concentrations achievable in human serum. Nevertheless, dalbavancin activity was affected by an increased concentration of extracellular DNA in the biofilm matrix. This study provides novel insight for designing more targeted therapeutic strategies against MRSA and to prevent or eradicate harmful biofilms.

Anti-Biofilm Effects of Torilis japonica Ethanol Extracts against Staphylococcus aureus.

The spread of antibiotic-resistant strains of Staphylococcus aureus, a gram-positive opportunistic pathogen, has increased due to the frequent use of antibiotics. Inhibition of the quorum-sensing systems of biofilm-producing strains using plant extracts represents an efficient approach for controlling infections. Torilis japonica is a medicinal herb showing various bioactivities; however, no studies have reported the anti-biofilm effects of T. japonica extracts against drug-resistant S. aureus. In this study, we evaluated the inhibitory effects of T. japonica ethanol extract (TJE) on biofilm production in methicillin-sensitive S. aureus (MSSA) KCTC 1927, methicillin-resistant S. aureus (MRSA) KCCM 40510, and MRSA KCCM 40511. Biofilm assays showed that TJE could inhibit biofilm formation in all strains. Furthermore, the hemolysis of sheep blood was found to be reduced when the strains were treated with TJE. The mRNA expression of agrA, sarA, icaA, hla, and RNAIII was evaluated using reverse transcription-polymerase chain reaction to determine the effect of TJE on the regulation of genes encoding quorum sensing-related virulence factors in MSSA and MRSA. The expression of hla reduced in a concentration-dependent manner upon treatment with TJE. Moreover, the expression levels of other genes were significantly reduced compared to those in the control group. In conclusion, TJE can suppress biofilm formation and virulence factor-related gene expression in MSSA and MRSA strains. The extract may therefore be used to develop treatments for infections caused by antibiotic-resistant S. aureus.

Canine Cystitis - Biofilm Formation by Bacterial Isolates

Background: Biofilms have been reported as important virulent markers associated with drug resistance in urinary tract infections (UTIs) in humans and dogs. However, in veterinary medicine, researches involving biofilm formation, treatments and preventions have been limited; yet, it is still possible to find few studies demonstrating biofilm-forming bacteria associated with different comorbidities such as otitis, wound infections, UTIs, and endometritis. These studies generally select dogs with chronic and recurrent infections, which could be an important factor in antibiotic resistance. We aimed to evaluate biofilms in sporadic cystitis regarding prevalence and drug resistance.Materials, Methods &amp; Results: Urine samples were collected by cystocentesis from 36 client-owned dogs under clinical and laboratory suspicion of non-recurrent urinary bladder infection (cystitis). Urine was aseptically plated onto blood agar, MacConkey, and CLED, followed by incubation for 24 to 48 h. Definitive identification of a potential pathogen was made by subculture collected from an isolated colony to obtain a pure culture. The gram staining method and specific biochemical tests (phenol red fermentation, lysine, phenylalanine, citrate, sulfide-indole-motility, and urease) were used to distinguish and classify the bacteria. After identification, the bacteria were tested for antimicrobial susceptibility by a standard disk diffusion method, using the following antimicrobials: amoxicillin with clavulanic acid, ampicillin, ceftriaxone, ciprofloxacin, clindamycin, cefazolin, cephalothin, erythromycin, gentamicin, norfloxacin, and sulfamethoxazole-trimethoprim. The biofilm-forming ability was determined based on a culture in Congo red agar (CRA), where biofilm producer strains formed black colonies with a dry crystalline surface, while non-biofilm producer strains formed red colonies with a smooth surface. A crystal violet dye assay was used to confirm the CRA results. Of the 36 urine samples collected from dogs with suspected cystitis, a total of 37 isolates were obtained, from mixed or pure cultures. The most prevalent bacteria were Escherichia coli (11/37), followed by Staphylococcus spp. (8/37), Proteus spp. (7/37), and Enterococcus spp. (5/37). Other less prevalent bacteria were Klebsiella spp., Streptococcus spp., and Enterobacter spp. As for biofilm-forming ability, 67.6% (25/37) of the 37 bacterial isolates had biofilm formation in CRA and 54.05% (20/37) on the microplates containing crystal violet dye. There was no statistical difference in antimicrobial susceptibility between biofilm producer and non-biofilm producer bacteria.Discussion: We found a high proportion (&gt; 54%) of in vitro biofilm-forming ability by different bacteria, which may indicate that biofilms may also be formed in vivo, in simple cystitis. Antimicrobial resistance was not noticed in bacteria capable of forming a biofilm; however, in a future study it is important to evaluate bacterial resistance in vivo, considering the possibility of having a different response than in vitro. In addition, the problem of the presence of a biofilm in vivo is that it can nullify the antimicrobial efficacy of therapeutic agents even with in vitro susceptibility. Besides the possibility of slow or incomplete diffusion of antibiotics through the extracellular matrix of the biofilm, aspects like hydration level, pCO2, pO2, pH, pyrimidine, and divalent cation concentration that negatively influence antimicrobial activity in vitro can also cause undesirable effects at the profound layers of the biofilm. In conclusion, all of the genera of bacteria isolated from dog’s sporadic cystitis in this study were able to form a biofilm in vitro. The pathogenicity and antibiotic resistance of bacteria appears unrelated to biofilm formation in vitro.Keywords: sessile bacteria, urine, simple cystitis, antibiotic resistance.

Methicillin- and Vancomycin-Resistant Staphylococcus aureus From Humans and Ready-To-Eat Meat: Characterization of Antimicrobial Resistance and Biofilm Formation Ability.

Methicillin-resistant and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA) are zoonotic life-threatening pathogens, and their presence in food raises a public health concern. Yet, scarce data are available regarding MRSA and VRSA in both ready-to-eat (RTE) meat and food handlers. This study was undertaken to determine the frequency, antimicrobial resistance, and biofilm-forming ability of MRSA and VRSA isolated from RTE meat (shawarma and burger) and humans (food handlers, and hospitalized patients) in Zagazig city, Sharkia Governorate, Egypt. We analyzed 176 samples (112 human samples: 72 from hospitalized patients and 40 from food handlers, 64 RTE meat samples: 38 from shawarma and 26 from burger). Using phenotypic, PCR-based identification of nuc gene and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), 60 coagulase-positive S. aureus (COPS) isolates were identified in the samples as follow: RTE meat (15/64, 23.4%), hospitalized patients (33/72, 45.8%) and food handlers (12/40, 30%). All the COPS isolates were mecA positive (and thus were classified as MRSA) and multidrug resistant with multiple antibiotic resistance indices ranging from 0.25 to 0.92. Overall, resistance to cefepime (96.7%), penicillin (88.3%), were common, followed by ampicillin-sulbactam (65%), ciprofloxacin (55%), nitrofurontoin (51.7%), and gentamicin (43.3%). VRSA was detected in 30.3% of COPS hospitalized patient’s isolates, 26.7% of COPS RTE meat isolates and 25% of COPS food handler’s isolates. VanA, vanB, or both genes were detected in 64.7, 5.9, and 29.4% of all VAN-resistant isolates, respectively. The majority of the COPS isolates (50/60, 83.3%) have biofilm formation ability and harbored icaA (76%), icaD (74%), icaC (50%), and icaB (46%) biofilm-forming genes. The bap gene was not detected in any of the isolates. The ability of MRSA and VRSA isolates to produce biofilms in addition to being resistant to antimicrobials highlight the danger posed by these potentially virulent microorganisms persisting in RTE meat, food handlers, and patients. Taken together, good hygiene practices and antimicrobial surveillance plans should be strictly implemented along the food chain to reduce the risk of colonization and dissemination of MRSA and VRSA biofilm-producing strains.

Prevention, inhibition, and degradation effects of melittin alone and in combination with vancomycin and rifampin against strong biofilm producer strains of methicillin-resistant Staphylococcus epidermidis

Methicillin-resistant Staphylococcus epidermidis (MRSE) bacteria are being recognized as true pathogens as they are able to resist methicillin and commonly form biofilms. Recent studies have shown that antimicrobial peptides (AMPs) are promising agents against biofilm-associated bacterial infections. In this study, we aimed to explore the antibiofilm activity of melittin, either alone or in combination with vancomycin and rifampin, against biofilm-producing MRSE strains. Minimum biofilm preventive concentration (MBPC), minimum biofilm inhibition concentration (MBIC), and minimum biofilm eradication concentration (MBEC), as well as fractional biofilm preventive-, inhibitory-, and eradication concentrations (FBPCi, FBICi, and FBECi), were determined for the antimicrobial agents tested. Cytotoxicity and hemolytic activity of melittin at its synergistic concentration were examined on human embryonic kidney cells (HEK-293) and Red Blood Cells (RBCs), respectively. The effect of melittin on the downregulation of biofilm-associated genes was explored using Real-Time PCR. MBPC, MBIC, and MBEC values for melittin were in the range of 0.625–20, 0.625–20, and 10–40 μg/μL, respectively. Melittin showed high synergy (FBPCi, FBICi and FBECi < 0.5). The synergism resulted in a 64–512-fold, 2–16 and 2–8-fold reduction in melittin, rifampicin and vancomycin concentrations, respectively. The synergistic melittin concentration found to be effective did not manifest either cytotoxicity on HEK-293 or hemolytic activity on RBCs. Results showed that melittin downregulated the expression of biofilm-associated icaA, aap, and psm genes in all isolates tested, ranging from 0.04-folds to 2.11-folds for icaA and from 0.05 to 3.76-folds for aap and psm. The preventive and therapeutic indexes of melittin were improved 8-fold when combined with vancomycin and rifampin. Based on these findings, the combination of melittin with conventional antibiotics could be proposed for treating or preventing biofilm-associated MRSE infections.

Antimicrobial activity of RK-7 peptide mimic against Staphylococcus aureus in solution and when immobilised onto contact lenses

Purpose: Our previous studies had shown that antimicrobial peptide-coated contact lenses could lose activity due to proteolysis. Antimicrobial peptide mimics are resistant to proteases. Therefore, the purpose of this study was to evaluate the antimicrobial activity of RK-7 peptide mimic against a drug resistant (mecA-positive, ciprofloxacin and ceftazidime resistant) and biofilm producing strain of Staphylococcus aureus in solution and when surface immobilised onto contact lenses.

Biofilm-overproducing Bacillus subtilis B12ΔYwcc decreases Cd uptake in Chinese cabbage through increasing Cd-immobilizing related gene abundance and root surface colonization

Biofilm-producing bacteria can decrease Cd uptake in vegetables, but mechanisms underlying this effect are poorly characterized. In this study, two mutant strains B12ΔYwcc and B12ΔSlrR were constructed from a biofilm-producing Bacillus subtilis strain B12. Then, the impacts of strain B12 and its high biofilm-producing mutant strain B12ΔYwcc and low biofilm-producing mutant strain B12ΔSlrR on Cd availability and uptake in Chinese cabbage and the related mechanisms were investigated in the Cd-polluted soil. Strain B12 and its mutants B12ΔYwcc and B12ΔSlrR increased the dry biomasses of edible tissues by 54%–130% compared with the controls. Strain B12 and its mutant B12ΔYwcc reduced the soil available Cd content by 36%–50% and root and edible tissue Cd contents by 23%–50% compared with the controls. Furthermore, the mutant strain B12ΔYwcc reduced the edible tissue Cd content by 40% and increased the polysaccharide content by 23%, invertase activity by 139%, and gene copies of the cumA by 4.5-fold, epsA by 7.1-fold, and cadA by 4.3-fold, which were involved in Cd adsorption in the rhizosphere soils, respectively, compared with strain B12. The polysaccharide content and cumA, epsA, and cadA gene copy numbers showed significantly reverse correlations with the available Cd content. Notably, the mutant strain B12ΔYwcc showed better ability to colonize the vegetable root surface than strain B12. These findings demonstrated that the biofilm-overproducing mutant strain B12ΔYwcc increased the polysaccharide production and Cd-immobilizing related cumA, epsA, and cadA gene copies, resulting in lower Cd availability and accumulation in Chinese cabbage in the Cd-polluted soil.

Pseudomonas aeruginosa Isolated from the Environment of a Veterinary Academic Hospital in Brazil - Resistance Profile

Background: The presence of resistant and potentially virulent bacterial strains in a veterinary hospital environment is a neglected problem. Pseudomonas aeruginosa is an opportunistic microorganism present and circulating in the veterinary hospital environment, of clinical importance and zooanthroponotic transmission of P. aeruginosa has also been reported. The aim of this study was to characterize the population of P. aeruginosa present in a veterinary hospital environment by evaluating their resistance profile and biofilm production.Materials, Methods &amp; Results: A total of 306 samples were collected from the veterinary hospital environment (swabs from consultation tables, surgical tables, door handles, hospitalization cages, stethoscopes, thermometers, and muzzles). The isolates were biochemically identified as belonging to the species Pseudomonas aeruginosa through nitrate to nitrite reduction, motility and oxidase test, growth at 42°C, pigment production, and alkalinization of acetamide. Antimicrobial resistance was tested using the minimum inhibitory concentration (MIC) test. Twenty seven isolates of P. aeruginosa were obtained, with a frequency of 8.8%. The detection of beta-lactamase production and biofilm formation genes by polymerase chain reaction (PCR). Two multidrug resistant (MDR) and 3 single-drug resistant (SDR) strains of P. aeruginosa were identified. Furthermore, it was observed that the strains carried genes related to beta-lactamase production (TEM and CTX-M group 25) and biofilm production (pelA, pslA, ppyR).Discussion: Pseudomonas aeruginosa is considered a major cause of opportunistic hospital infections, as it causes significant morbidity and mortality in immunosuppressed individuals, both in animals and in humans. Veterinary hospitals can harbor microorganisms that cause infections, as well as multiresistant agents. Normally, these environments have a large circulation of people and animals, which particularly enables a facilitated dissemination of these resistant microorganisms. Recently, the World Health Organization (WHO) listed carbapenem-resistant P. aeruginosa as one of 3 bacterial species in critical need for the development of new antibiotics to treat their infections. The data found in this work strengthen the knowledge on the antimicrobial resistance capacity that P. aeruginosa exhibits. The presence of 3 multiresistant strains further highlights the advanced stage of resistance of this bacterial species. The characterization of strains of this species in a veterinary hospital environment is crucial for the control of this population circulating in this environment, and the consequent adoption of more effective measures aimed at controlling its proliferation. The study of this bacterial species in a veterinary hospital environment has a direct impact on human health, due to the mechanisms of resistance and genetic variability that can occur between infections in different animal species and in humans. In view of that, professionals working in veterinary hospitals should be aware of the importance of controlling these microorganisms. Correct measures must be taken to sanitize the environment and utensils between animal care sessions, besides frequent hand washing by all employees and the use of protective equipment such as masks and gloves. The presence of potentially biofilm-producing MDR and SDR strains indicates the free circulation of these bacteria in the veterinary hospital environment. Thus, as a potentially pathogenic microorganism to humans and animals, containment measures must be taken to prevent this possible transmission.Keywords: bacteria, antimicrobial resistance, multidrug resistant, beta-lactamase, biofilm, veterinary care.

Analysis of Gtpases Rab 5 and Rab 7 expression from macrophages infected with biofilm-producing and non biofilm-producing strains of Corynebacterium pseudotuberculosis.

Corynebacterium pseudotuberculosis is a facultative intracellular pathogen that uses various mechanisms to survive within macrophages. In phagocytosis, this survival can be attributed to the ability to inhibit phagosome-lysosome fusion. In this fusion, some proteins, including Rabs GTPases, are involved in the maturation process and are responsible for regulating membrane vesicle trafficking. Thus, to better understand these mechanisms, the capacity of biofilm-producing and non biofilm-producing strains of Corynebacterium pseudotuberculosis for modulating the expression of endosomal proteins GTPases Rab 5 and Rab 7 was evaluated in an in vitro study of infection of goat macrophages. Blood was collected from ten Canindé goats, infected with biofilm-producing and non biofilm-producing strains of C. pseudotuberculosis. Blood cells were separated in colloidal silica-polyvinylpyrrolidone gradients (GE Healthcare®). These cells were maintained at 37°C, with 5% of CO2. After differentiation, macrophages were infected with the mentioned strains. The bacterial pellets were marked with Rab 5 and Rab 7 antibodies, and their expression was observed by flow cytometry. Both strains of C. pseudotuberculosis (biofilm-producing and non biofilm-producing) were observed to be capable of altering the expression of Rab proteins in macrophages cultivated in vitro. Macrophages from the animals infected with the biofilm-producing strain had an increase in the expression of Rab 5 protein, mainly when these macrophages were treated with the non biofilm-producing strain. The same mechanism was shown to function with Rab 7 protein, however at a lower intensity of expression when compared with Rab 5.