Prevalence of quinolone-resistant uropathogenic Escherichia coli in a tertiary care hospital in south Iran

Background: Quinolones are a family of synthetic antimicrobial agents with a broad antibacterial activity commonly used as a suitable therapy in patients with urinary tract infection (UTI). In the present study, we aimed to evaluate the prevalence of quinolones resistance and the presence of plasmid-mediated quinolone resistance (PMQR) genes among Escherichia coli isolates. METHODS: This study was performed on a collection of 121 E. coli isolates derived from patients with UTI. Antimicrobial susceptibility to nalidixic acid, ciprofloxacin, levofloxacin, norfloxacin, and ofloxacin was specified by the disk diffusion method. The presence of PMQR genes was determined by PCR method. RESULTS: Antibiotic susceptibility results showed that the highest and lowest resistance rates were against nalidixic acid (71.9%) and norfloxacin (44.6%), respectively. The molecular results showed that 40 (33.1%) and 15 (12.4%) of the isolates were positive for qnrS and qnrB genes, respectively. Meanwhile, 5 (4.1%) of the isolates were found positive for both genes, while none were found to be positive for qnrA gene. There was no significant association between the presence of qnr genes and higher antibiotic resistance. CONCLUSION: We found high levels of quinolones resistance (more than 40%) among E. coli strains isolated from patients with UTIs in the south of Iran. We further report the prevalence of PMQR genes among uropathogenic E. coli; however, it seems that these genes are not the main components of quinolone resistance in our region.