Introduction & Objective: Fluoroquinolones are essential antimicrobial agents used to treat UTIs. Clinical experiences have shown a high rate of antibiotic resistance among uropathogens. These resistance are usually the consequence of mutations involving genes encoding gyrA and parC. The aim of this study was to determine antimicrobial resistance pattern and the presence of mutations in regions that code for quinolone resistance in the genes gyrA and parC in clinical isolates of E. coli from a hospital in Isfahan, Iran.    

Materials & Methods: A total of 135 isolates of E.coli (from urine) were collected from September to February 2013 from Alzahra Hospital (Isfahan, Iran). Bacterial susceptibility to antimicrobial agents was determined using disk diffusion method. PCR was performed to detect genes gyrA and parC. Then, 13 isolates were randomly chosen for genetic characterization of the quinolone-determining region (QRDR) of the parC and gyrA genes.

Results: Among 135 E. coli isolates, 61 isolates ( 45 % ) were resistant to fluoroquinolones. From 13 isolates, 11 isolates showed two mutations (Ser83Leu/ Asp87Asn) and 2 isolates showed a single mutation (Ser83Leu) in gyrA gene. Also, five different mutations were detected in parC gene in the E. coli isolates, encoding Ser80Ile, Ser80Val, Ser80Arg, Glu84Val, Gly78Ser.

Conclusion: More research on the molecular basis of FQ resistance is required to develop new therapeutic strategies for FQ-resistant E. coli. To overcome antibiotic resistance antibiotic therapy should be limited and based on the susceptibility patterns of microorganisms.