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. ResultsIn the present study, the highest MIC 90 and MIC 95 (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). Furthermore, there was no significant association between the presence of biocide resistance genes and antibiotic resistance (p > 0.05), except for levofloxacin and norfloxacin antibiotics and qacE and qacG genes (p < 0.05). Conclusion Our results revealed that chlorhexidine digluconate is the most effective biocide against P. aeruginosa isolates in Ardabil hospitals. However, we recommend continuous monitoring of the antimicrobial activity of biocides and the prevalence of biocide-associated resistance genes for a better prevention of microorganism dissemination and infection control in hospitals.

Background: Carbapenems are the most commonly administered drugs for the treatment of multidrug-resistant Pseudomonas aeruginosa (MDR-P. aeruginosa) infections. However, carbapenem-resistant P. aeruginosa is spreading rapidly and has led to a new threat to human health worldwide. Objectives: The current study aimed to determine the prevalence of imipenem-resistant P. aeruginosa, detect metallo-β-lactamase (MBL)-producer isolates, and evaluate their clonal relationships in strains isolated from patients referring to the hospitals of Ardabil city, Iran. Methods: The resistance rate to imipenem was evaluated using the disk diffusion method. Double-disk synergy test and PCR technique were used for phenotypic and genotypic screening of MBL-positive P. aeruginosa, respectively. Ultimately, ERIC-PCR and MLST methods were used for assessing clonal relatedness among the isolates. Results: The prevalence of imipenem-resistant P. aeruginosa strains was estimated at 57.1% (48 out of 84 isolates). In addition, 45 (93.7%) out of 48 imipenem-resistant P. aeruginosa isolates were phenotypically screened as MBL-positive, among which 16 (35.5%) and three (6.6%) isolates harbored blaIMP and blaVIM-1 genes, respectively. However, blaNDM, blaSIM-2, blaSPM, and blaGIM-1 genes were not detected in this study. MBL-producing P. aeruginosa strains were divided into 42 ERIC-PCR types. Based on the results of MLST, P. aeruginosa ST235 was the only identified sequence type. Conclusions: Our results revealed a high and alarming prevalence of imipenem-resistant and blaIMP-positive P. aeruginosa ST235 at Ardabil hospitals. Continuous monitoring is essential to control the further spread of this highly virulent and drug-resistant clone.

Background & objectives: Bacterial antibiotic resistance is becoming a global health crisis. The aim of this descriptive, cross-sectional study was to investigate the prevalence of multidrug-resistant Pseudomonas aeruginosa strains in Ardabil. Methods: During 9 months, between July 2019 and March 2020, 50 strains of Pseudomonas aeruginosa were collected from different clinical specimens in four hospitals of Ardabil and the prevalence of MDR, XDR and PDR strains of Pseudomonas aeruginosa were evaluated. Antibiotic susceptibility testing was assessed using the disk diffusion method. Results: In the present study, the prevalence of MDR, XDR and PDR strains of Pseudomonas aeruginosa were 52%, 40% and 14%, respectively. Conclusion: Due to high prevalence of multidrug-resistant strains of Pseudomonas aeruginosa in Ardabil, continuous monitoring of the antibiotic resistance trend in clinical isolates in order to select the best medication is necessary.

Background: Biocides are frequently used as preservative, disinfectant and sterilizer against many microorganisms in hospitals, industry and home. However, the resistance 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 value was observed for benzalkonium chloride (MIC90=1024 μg/mL), followed by formaldehyde (MIC90=512 μg/mL), triclosan (MIC90=512 μg/mL) and chlorhexidine digluconate (MIC90=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). Furthermore, there was no significant association between the presence of biocide resistance genes and antibiotic resistance (p>0.05), except for levofloxacin and norfloxacin antibiotics and qacE and qacG genes (p<0.05). Conclusion: Our results revealed that chlorhexidine digluconate is the most effective biocide against P. aeruginosa isolates in Ardabil hospitals. However, we recommend continuous monitoring of the antimicrobial activity of biocides and the prevalence of biocide-associated resistance genes for a better prevention of microorganism dissemination and infection control in hospitals.