The Frequency of qnr Genes in Extended-Spectrum β-lactamases and non-ESBLs Klebsiella pneumoniae Species Isolated from Patients in Mashhad, Iran

Since the fluoroquinolones are the broad-spectrum antibiotics, they affect both Gram-negative and Gram-positive bacteria. These antibiotics are widely prescribed by physicians. As a result, some bacteria, especially Enterobacteriaceae, have shown a resistance to this family of antibiotics The current study aimed at detecting the frequency of , and genes, novel plasmid-mediated quinolone-resistance genes, among extended-spectrum β-lactamases (ESBL)-positive and ESBL-negative isolates. One hundred and thirty isolates of were collected from Imam Reza Hospital and its associated clinics from May 2011 to July 2012. The isolates were tested for ESBLs by the conventional methods. Polymerase chain reaction (PCR) was performed to amplify , and . Thirty-eight (29.3%) isolates were ciprofloxacin-resistant. Among 130 infectious isolates, 56 (43%) were capable of producing ESBL; 10.8% (n=14), 15.4% (n=20), and 20.8% (n=27) of ESBL-producing were positive for , and , respectively, and 13.8% (n=18) of the isolates harbored 2 or 3 genes. The results of the current study showed that quinolone-resistance genes were more frequent in ESBL-producing (37.5%) isolates, compared with the ESBL-negative isolates (20.89%). The prevalence of genes was high in isolates, with higher frequency in ESBL-positive strains. Most of the isolates were positive for all 3 groups of genes and the was the most common one.