Frequency of Plasmid-Mediated Quinolone Resistance Genes qnrA, qnrB, and qnrS among Clinical Isolates of Klebsiella pneumoniae

Document Type : Original Article


1 Departments of Microbiology, Damghan Branch, Islamic Azad University Damghan, Iran

2 Departments of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran


Introduction: Plasmid-mediated quinolone resistance (PMQR) is a growing clinical concern throughout the world. The purpose of this study was to detect qnr-encoding genes and to evaluate the clonal relatedness of qnr-positive Klebsiella pneumoniae isolates.
Materials and Methods: A total of 88 K. pneumoniae isolates assessed to quinolone which were obtained from Tehran hospital in Tehran, Iran. Bacterial identification was administrated using standard laboratory methods. Quinolone resistance was determined using the Kirby-Bauer disk diffusion method according to the Clinical Laboratory Standards Institute (CLSI) guidelines. The PCR was employed to detect qnrA, qnrB and qnrS genes.
Results: The results of disk diffusion showed that 39.3%, 32.1%, 27.4%, 27.1%, 22.6% of strains were fully resistant to nalidixic, norfloxacin, ofloxacin, ciprofloxacin and levofloxacin, respectively. The qnrB (43% isolates) was the most commonly detected gene, followed by qnrS (34% isolates) and qnrA (23 % isolates) either alone or in combination with other genes.
Conclusions: This study describes the high prevalence of the qnrB, qnrS, and qnrA genes among K. pneumoniae isolates in Iran. The detection of qnr genes accentuate the need for organizing tactful policies associated with infection control measures in hospital settings in Iran.