Study of Plasmid-Mediated Quinolone Resistance in Escherichia coli from Nosocomial Urinary Tract Infections.

The aim of the present study was to study the prevalence of plasmid-mediated quinolone resistance (PMQR) genes (qnrA, qnrB, qnrC, qnrD, qnrS, qepA, oqxA, oqxB and aac) in Escherichia coli (E. coli) isolated from patients with nosocomial urinary tract infections (UTIs) and its relation to the extended-spectrum β-lactamase (ESBL) production. ; Methods: A cross-sectional study was carried out on 200 non-duplicated isolates of E. coli isolated from patients with nosocomial UTIs. E.coli isolates were subjected to antibiotic susceptibility testing by disc diffusion method, determination of minimum inhibitory concentrations (MICs) of ciprofloxacin by Epsillometer (E) test strips, detection of ESBL production by double disc synergy method and detection of qnrA, qnrB, qnrC, qnrD, qnrS, qepA, oqxA, oqxB and aac genes by polymerase chain reaction (PCR). ; Results: The antimicrobial susceptibility testing of the isolated E. coli revealed a high frequency of resistance to ampicillin (73.5%), ceftazidime (72%) and imipenem (71.5%). The less frequent resistance was for aztreonam (21.5%), amikacin (36.5%) and gentamicin (38.5%). ESBL production was found in 131 isolates (65.5%) and phenotypic quinolone resistance was detected by MIC in 65 isolates (32.5%), with 52.3% of them showed high resistance to ciprofloxacin with an MIC more than 32 μg/ml. PMQR genes were found in 40 isolates. The frequency of the detected genes was 40%, 37.5%, 35%, 20% and 5% for qnrA, qnrS, qepA, qnrB and oqxA, respectively. Significant association was found between the presence of PMQR genes and ESBL production (P=0.0001). ; Conclusion: The study highlights the prevalence of PMQR genes in E. coli with high association with the ESBL phenotype. This finding is a sign of limited therapeutic options for E. coli.