Investigation of plasmid-mediated quinolone resistance genes among clinical isolates of Klebsiella pneumoniae in southwest Iran

Background Extensive and inappropriate use of quinolones has led to growing resistance rates to these broad-spectrum antibiotics. The present study purposed to investigate the prevalence of plasmid-mediated quinolone resistance (PMQR) genes in Klebsiella pneumoniae clinical isolates. Method Ninety-two non-repetitive K. pneumoniae clinical isolates were confirmed by standard microbiological methods. Antibacterial susceptibility of isolates toward seven agents from the quinolone family was evaluated by the disc diffusion method. Ciprofloxacin minimum inhibitory concentrations (MICs) were determined using the standard agar dilution method. PCR amplification was used to detect the existence of PMQR genes in the studied isolates. Results In the present study, significant quinolones' resistance (40%) was observed in K. pneumoniae isolates, and most of the strains were resistant to nalidixic acid (94.6%) and ofloxacin (45.6%). MIC analysis showed 15 strains were resistant to 6-128 mu g/ml of ciprofloxacin, and five were intermediately-resistant. PMQR genes were detected in 88% of all isolates. Acc(6')-Ib-cr was constituted half of the total PMQR genes detected among ciprofloxacin non-susceptible isolates. Of 20 ciprofloxacin non-susceptible isolates, 65% (n = 13) harbored multiple PMQR determinants, and 15 strains were determined as integron carriage. Conclusion The findings of this study indicated considerable resistance against quinolones, which could be correlated with the extensive and inappropriate use of this class of antibiotics as empirical treatment.

Automated summary

This study found significant quinolone resistance in Klebsiella pneumoniae isolates, with most strains showing resistance to nalidixic acid and ofloxacin. MIC analysis revealed a high percentage of isolates resistant to ciprofloxacin, with a majority harboring PMQR genes. The findings suggest a considerable level of resistance against quinolones, potentially due to their extensive and inappropriate use.