Journal of Medical Bacteriology 2016. 5(5-6):39-45.

Frequency of Quinolone Resistance and qnrB and qnrC Genes in Clinical Isolates of Klebsiella pneumoniae
Maryam Moghadasi, Mohsen Mirzaee, Mohammad Reza Mehrabi


Background:   Klebsiella pneumoniae is among the most common and significant agents of community and hospital-acquired infections. Plasmid mediated quinolone resistance (PMQR) was increasingly identified in Enterobacteriaceae family worldwide. Plasmid-mediated quinolone resistance (PMQR) was first reported in 1998 from a Klebsiella pneumoniae isolate in the USA. Till date, five Qnr proteins have been identified; QnrA, QnrB, QnrC, QnrD and QnrS. Quinolone are broad spectrum antibiotics the resistant to which has increasingly been reported among many bacterial species including Klebsiella. The aim of this study was the antibiotic resistance profile was determined based on resistance and molecular characterization of qnrB and qnrC genes in Klebsiella pneumoniae clinical isolated.

Methods:   In this cross sectional study, 94 samples of K. pneumoniae were collected. Isolates were screened for quinolone antibiotics resistance using disk diffusion method according to clinical and laboratory standards institute (CLSI) guidelines. Isolates with resistance to at least one of the quinolone antibiotics, examined for presence of the qnrB and qnrC genes.

Results:  Based on the obtained results by the Agar disk diffusion test, 29.78%, 27.65%, 28.72% and 27.65% of the isolates were resistant to nalidixic acid, ciprofloxacin, norfloxacin and ofloxacin, respectively. Of these 46.66% carried qnrB, 3.33% carried qnrC genes.


Conclusion:   The identification of qnrB gene among quinolone-resistant K. pneumoniae isolates shows that the emergence of PMQR in this region requires serious preventive measures.


Klebsiella pneumoniae; Quinolone Resistance; qnr Genes

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