Frequency of Plasmid-mediated Quinolone Resistance in Citrobacter Isolated From Urinary Tract Infection

Abstract

Background and Objectives: Plasmid-mediated quinolone resistance (PMQR) plays an essential role in developing resistance to quinolones. This study aimed to investigate the presence and effect of PMQR genes in clinical isolates of Citrobacter from urinary tract infections. Methods: Fifty-one citrobacter isolates were found in urinary samples of patients referred to Imam Reza Hospital in Kermanshah City, Iran, in 2019. The susceptibility to antibiotics was determined by disk diffusion and broth microdilution methods. The qnrA, qnrB, qnrS, aac (6 ')-Ib, and qepA genes of isolates were detected by the polymerase chain reaction (PCR) method. Then, the PCR-RFLP (restriction fragment length polymorphism) method was used to differentiate the aac (6')-Ib gene from its aac (6')-Ib-cr variant. The obtained data were analyzed using the chi-square and Mann-Whitney statistical methods. Results: The highest resistance of isolates was seen against cefazolin (74.5%), ciprofloxacin (41.2%), and cotrimoxazole (35.3%). More than 80% of isolates were susceptible to carbapenems, gentamicin, and piperacillin/tazobactam. The frequency of qnr genes in isolates was 41.5%. The qnrB gene was the most frequent (43.2%), followed by qnrS (5.9%) and qnrA (1.9%). The aac (6') -Ib gene was found in 27.5% of the isolates; all were aac (6')-Ib-cr. The qepA gene was not found in any isolate. Conclusion: The results of this study indicate the importance of Citrobacter freundii as an agent of urinary tract infection and its high resistance to ciprofloxacin. PMQR genes are highly prevalent in Citrobacter isolates, and there is a significant correlation between the qnrB and qnrS genes with the increased minimum inhibitory concentration of ciprofloxacin. Therefore, antibiotic susceptibility should be performed before treating Citrobacter urinary tract infections.

Keywords

• citrobacter
• fluoroquinolones
• plasmid