Fluoroquinolone Resistance in Clinical Isolates of Klebsiella Pneumoniae

Introduction  Fluoroquinolones are widely used broad-spectrum antibiotics. Recently, increased rate of resistance to this antibiotic has been observed in Klebsiella pneumoniae. The aim of the present study was to determine the presence of quinolone resistance determining regions (QRDR) mutation genes and plasmid-mediated quinolone resistance (PMQR) determinants in clinical isolates of ciprofloxacin-resistant K. pneumoniae. Material and Methods  The study included 110 nonduplicate ciprofloxacin-resistant K. pneumoniae clinical isolates. Antibiotic susceptibility testing by disk diffusion method and minimum inhibitory concentration (MIC) by agar dilution methods for ciprofloxacin was performed according to the recommendations of Clinical Laboratory Standards Institute. The presence of QRDR genes and PMQR genes was screened by polymerase chain reaction (PCR) amplification. Result  All 110 isolates were resistance to ciprofloxacin, levofloxacin, and ofloxacin. As much as 88% of the isolates exhibited high-level of MIC to ciprofloxacin. Among the 110 isolates, 94(85%) harbored gyrA and 85 (77%) gyrB. The parC and parE genes were detected in 88 (80%) and 64 (58%) isolates. qnrB was detected in 13 (12%) isolates and qnrS in 5 (4.5%) isolates. Two (1.8%) isolates carried both qnrB and qnrS genes. The acc (6')-Ib-cr gene was found in 98 (89%) isolates and oqxAB was detected in 7 (6.3%) isolates. One (0.9%) isolate carried qnrB, acc(6')-Ib-cr and oqxAB genes. Conclusion  The prevalence of acc (6')-Ib-cr gene is high among PMQR determinants, followed by qnrB, oqxAB and qnrS.