The Frequency of Plasmid qnr Genes in Quinolone-Resistant Isolates of Escherichia Coli Causing Urinary Tract Infection

Escherichia coli is one of the main causes of urinary tract infection in humans. The bacteria have become resistant to antibiotics and its treatment is difficult. The plasmid-dependent resistance to quinolones is increasing in the family of Enterobacteriaceae. This study aimed to assess the frequency of plasmid qnr genes in quinolone-resistant isolates of Escherichia coli causing urinary tract infection In this descriptive study, 96 isolates of Escherichia coli were identified. Antibiotic susceptibility of isolates was investigated using disc diffusion method. The presence of qnrA, qnrB, and qnrS plasmids was assessed using molecular methods with specific primers. Findings: Of the 96 isolates examined, 53 isolates (40.16%) were resistant to fluoroquinolone antibiotics. Moreover, the presence of qnrA gene in 18 isolates (33.96%), qnrB gene in 8 isolates (15.1%), and qnrS gene in 5 isolates (9.43%) of 53 isolates resistant to fluoroquinolones was confirmed via polymerase chain reaction (PCR) assay. The results of this study show that genes of plasmid-dependent qnr group have expanded in Isfahan City, Iran. The frequency of the qnrA gene relative to qnrB and qnrS is higher among quinolone-resistant Escherichia coli isolates in Isfahan.