Detection of Plasmid-Mediated qnr Genes Among the Clinical Quinolone-Resistant Escherichia coli Strains Isolated in Tehran, Iran

Abstract

Background:Escherichia coliis one of the most important bacterial agents to cause urinary tract infections. Inappropriate and unnecessary administration of antibiotics has led to an increase in the appearance of multidrug-resistantE. coliisolates, limiting treatment options. The increase in a number of resistant strains of bacteria is a major concern of health authorities worldwide.Objective:The purpose of this study was to determine the presence of theqnrgenes amongE. coliisolated from UTIs of patients in Baqiyatallah hospital in Tehran province, Iran.Method:Clinical urine samples of patients with suspected urinary tract infection were collected by standard methods in sterile disposable containers. After analysis of urine, microscopic observations and culture analysis, the bacterial genome was extracted by boiling method. PCR for detection ofqnrgenes includingqnrA,qnrBandqnrSwas done by specific primers, then PCR products were run using gel electrophoresis and visualized by gel documentation system.Results:In the present study among the 95 isolates, 60 strains were resistant to nalidixic acid. PCR showed that 92 strains were positive forqnrS. TheqnrAandqnrBgenes were not found among the clinical isolates.Conclusion:Our finding indicates a high level of resistance against nalidixic acid amongE. coliisolates recovered from the patients with UTI. Also, the high frequency ofqnrSimposes the importance of survey of molecular and genetic analysis of mechanisms of quinolone resistance inE. colistrains.