Prevalence of Chlorhexidine-Tolerant <i>Pseudomonas aeruginosa</i> and Correlation with Antibiotic Resistance

Background and Aim: Pseudomonas aeruginosa (P.aeruginosa) is a common environmental bacterium linked to the serious hospital-acquired infections.Chlorhexidine (CHX), a widely used antiseptic in hospitals, can create selection pressure that contributes to the cross-antibiotic resistance and the emergence of multidrug-resistant (MDR) strains.This study aimed to investigate the prevalence of tolerance to CHX and the presence of the pslA, pelA, qacE, and qacE1 genes among P. aeruginosa isolates in Shiraz, Southwest Iran. Materials and Methods:From October 2020 to July 2021, 120 P. aeruginosa isolates were collected from hospitalized patients at Nemazee Hospital in Shiraz, Southwest Iran.The Kerby-Bauer disk diffusion method was employed for the antimicrobial susceptibility testing.The susceptibility to CHX was evaluated using the microbroth dilution method.Finally, the prevalence of the pelA, pslA, qacE, and qacE1 genes was assessed among all P. aeruginosa isolates. Results:The highest resistance rate was observed against ceftriaxone and ceftazidime, with frequencies of 97.120 (80.8%) and 96.120 (80%), respectively.In contrast, the lowest resistance rates were noted for amikacin (5.120, or 4.2%), ofloxacin (7.120, or 5.8%), and meropenem (10.120, or 8.3%).Among the 120 P. aeruginosa isolates, 33 (27.5%) were CHX-tolerant, and 22 (18.3%) were MDR.There was a highly significant correlation between the rates of MDR and CHX-tolerant P. aeruginosa isolates (P<0.005). Conclusion:A positive association between the percentages of MDR strains and CHX-tolerant P. aeruginosa isolates has reinforced the hypothesis that exposure to CHX may contribute to developing cross-resistance.Thus, concise monitoring of CHX susceptibility seems essential in the hospital and clinical settings.