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. 2015 Nov;40(6):515-21.

Prevalence of qnr and aac(6')-Ib-cr Genes in Clinical Isolates of Klebsiella Pneumoniae from Imam Hussein Hospital in Tehran

Fereshteh Eftekhar PhD  1 , Seyed Mohsen Seyedpour MSc  1
Affiliations

Prevalence of qnr and aac(6')-Ib-cr Genes in Clinical Isolates of Klebsiella Pneumoniae from Imam Hussein Hospital in Tehran

Fereshteh Eftekhar PhD et al. Iran J Med Sci. 2015 Nov.

Abstract

Background: Plasmid mediated quinolone resistance (PMQR) has been shown to play an important role in resistance not only to quinolones, but also β-lactams and aminoglycosides. In fact, qnr genes are frequently carried along with β-lactamase determinants on the same plasmids. We studied the prevalence of qnrA, qnrB, qnrS and aac(6')-Ib-cr genes among quinolone and cephalosporin resistant clinical isolates of Klebsiella pneumoniae (K. pneumoniae), as well as the association between PMQR genes with resistance to quinolones, cephalosporins and aminoglycosides.

Methods: The study was conducted on 79 K. pneumoniae clinical isolates collected from Imam Hussein hospital in Tehran between July 2010 and January 2011, based on their resistance to quinilones and cephalosporins. Antibacterial susceptibility was determined to 15 antibiotics by disc diffusion. Presence of qnrA, qnrB, qnrS and aac(6')-Ib-cr genes were investigated using specific primers and PCR.

Results: Of the 79 K. pneumoniae isolates, 47 (59.5%) carried the PMQR determinants. Among these, 42 (89.4%) carried aac(6')-Ib-cr of which, 21 (50%) also harbored qnrB. Three isolates carried qnrB alone, two (4.2%) harbored qnrS and none had qnrA. Resistance to aminoglycosides and cephalosporins was significantly higher in the isolates carrying both qnrB and aac(6')-Ib-cr genes compared to aac(6')-Ib-cr alone.

Conclusion: This study showed a high prevalence of aac(6')-Ib-cr and qnrB genes among the Iranian K. pneumoniae clinical isolates as well as co-carriage of the two genes. There was a significant association between qnrB gene carriage and resistance to quinolones, cephalosporins, and aminoglycosides.

Keywords: Iran; Klebsiella pneumoniae; Qnr protein; Quinolone resistance.

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Figures

Figure 1
Figure 1
Shows gel electrophoresis of qnrB (A; lanes 1-6, and 7-13) and qnrS (B: lanes 1 and 2) genes in some isolates of K. pneumoniae by PCR. L: 1Kb Ladder, C-: negative control.
Figure 2
Figure 2
Shows gel electrophoresis of aac(6’)-Ib-cr gene in some isolates of K. pneumoniae by PCR (lanes 1-8 and 9-16). L: 1Kb Ladder, C-: negative control.
Figure 3
Figure 3
Shows comparison of antibiotic resistance profiles in K. pneumoniae isolates carrying only qnrB (black bars) with the isolates which harbored both qnrB+aac(6’)-Ib-cr (grey bars). NA: Nalidixic acid, CP: Ciprofloxacin, LOM: Levofloxacin, NOR: Norfloxacin, OFX: Ofloxacin, CTX: Cefotaxime, CAZ: Ceftazidime, CPM: Cefepime, GM: Gentamycin, AK: Amikacin, KM: Kanamycin.
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