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BACKGROUND Biocides are frequently used as preservative, disinfectant and sterilizer against many microorganisms in hospitals, industry and home. However, the reduced susceptibility rate of Pseudomonas aeruginosa (P. aeruginosa) strains to biocides is increasing. The aim of this study was to evaluate the antimicrobial activity of four frequently used biocides against P. aeruginosa and to determine the prevalence of genes involved in biocide resistance. METHODS A total of 76 clinical isolates of P. aeruginosa strains were used in the present study. The minimum inhibitory concentrations (MICs) of four biocides, i.e. chlorhexidine digluconate, benzalkonium chloride, triclosan and formaldehyde, against P. aeruginosa strains were determined using agar dilution method. In addition, the prevalence of biocide resistance genes was determined using the polymerase chain reaction (PCR) method. RESULTS In the present study, the highest MIC90 and MIC95 (epidemiological cut-off) values were observed for benzalkonium chloride (1024 μg/mL), followed by formaldehyde (512 μg/mL), triclosan (512 μg/mL) and chlorhexidine digluconate (64 μg/mL). Furthermore, the prevalence of qacEΔ1, qacE, qacG, fabV, cepA and fabI genes were 73.7% (n = 56), 26.3% (n = 20), 11.8% (n = 9), 84.2% (n = 64), 81.5% (n = 62) and 0% (n = 0), respectively. A significant association was observed between the presence of biocide resistance genes and MICs (p 0.05), except for levofloxacin and norfloxacin antibiotics and qacE and qacG genes (p

Enterococci are among the most common causes of nosocomial infections worldwide. Antimicrobial biocides are extensively used to control the growth of microorganisms on different surfaces. The purpose of this study was to determine the susceptibility of Enterococcus faecalis and Enterococcus faecium isolates collected in Iran to biocide agents, formaldehyde (FOR), benzalkonium chloride (BZC), triclosan (TRE), and chlorhexidine digluconate (CHDG). Additionally, the frequency of biocide tolerance-associated (BTA) genes, qacA/B, qacED1, emeA, sigV and gasp65 were investigated. In this study, 222 isolates of E. faecalis and 425 isolates of E. faecium from clinical and non-clinical sources were investigated. Minimum inhibitory concentration (MIC) of biocide agents was determined using agar dilution method. Biocides epidemiological cutoff values (ECOFFs) were determined using 95% rule. BTA genes were identified using PCR testing. ECOFFs for CHDG, BZC, TRE and FOR were 8 µg/mL, 16 µg/mL, 32 µg/mL and 512 µg/mL for both species, respectively. MIC values showed that the distribution of isolates with high level of tolerance to antimicrobial biocides was clearly different, depending on ecological niches. The BTA genes, qacA/B, qacED1, emeA, sigV and gasp65 were detected in 19.4% (43), 19.8% (44), 42.8% (95), 89.6% (199) and 70.2% (156) of E. faecalis and 10.3% (44), 17.2% (73), 27.8% (118), 42.2% (188) and 82.8% (352) of E. faecium isolates, respectively. Based on the distribution pattern of BTA genes 14 and 18 different profiles were identified for E. faecalis and E. faecium isolates respectively. Generally, the isolates carrying at least a single BTA gene showed higher MIC

Background In this study, antimicrobial resistance, virulence genes profile, and genetic relatedness among Enterococcus isolates obtained from a hospital in Ardabil were studied. Methods E. faecalis and E. Faecium isolates were identified using microbiological and molecular methods. Vancomycin minimum inhibitory concentrations (MICs) were determined by agar dilution assay. Antimicrobial resistance pattern was evaluated by the disk diffusion method. Vancomycin resistance and virulence genes were detected by polymerase chain reaction (PCR). Genetic relatedness among the vancomycin-resistant Enterococcus (VRE) isolates was evaluated by enterobacterial repetitive intergenic consensus (ERIC)-PCR. Results Totally, 96 Enterococcus isolates were collected. Of these, 72 (75%) and 24 (25%) cases belonged to E. faecalis and E. faecium species, respectively. One (1.4%) and 10 (41.7%) isolates of E. faecalis and E. faecium were found to be resistant to vancomycin, respectively. All the VRE isolates were positive for the vanA gene. Both E. faecalis and E. faecium species showed high rates of resistance to erythromycin (58.3%, 87.5%), tetracycline (50%, 79.16%), rifampicin (47.2%, 95.8%), and ciprofloxacin (38.9%, 75%), respectively. The resistance rates were significantly higher in VRE isolates compared to vancomycin-sensitive isolates (P ≤ 0.05). The lowest values were observed for resistance to nitrofurantoin (1.4% and 0.0%) and chloramphenicol (1.4% and 12.5%) in E. faecalis and E. faecium isolates, respectively. Most of the VRE isolates were recovered from urine specimens obtained from patients admitted to internal ward. gelE and asa1 were the major virulence genes in VRE isolates. High genetic diversity was observed among VRE isolates. Conclusion The high prevalence of genetically versatile and multidrug resistant E. faecium in our study indicates the need for careful infection control precautions.