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. 2011 Oct;31(4):257-64.
doi: 10.3343/kjlm.2011.31.4.257. Epub 2011 Oct 3.

Prevalence of plasmid-mediated quinolone resistance and its association with extended-spectrum beta-lactamase and AmpC beta-lactamase in Enterobacteriaceae

Haeng Soon Jeong  1 , Il Kwon Bae, Jeong Hwan Shin, Hee Jung Jung, Si Hyun Kim, Ja Young Lee, Seung Hwan Oh, Hye Ran Kim, Chulhun Ludgerus Chang, Weon-Gyu Kho, Jeong Nyeo Lee
Affiliations

Prevalence of plasmid-mediated quinolone resistance and its association with extended-spectrum beta-lactamase and AmpC beta-lactamase in Enterobacteriaceae

Haeng Soon Jeong et al. Korean J Lab Med. 2011 Oct.

Abstract

Background: We investigated the prevalence of plasmid-mediated quinolone resistance and its association with extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase in Enterobacteriaceae.

Methods: A total of 347 non-duplicated isolates of Enterobacteriaceae were collected between August and October 2006 from 2 hospitals. Qnr determinant screening was conducted using PCR amplification, and all positive results were confirmed by direct sequencing. Qnr-positive strains were determined on the basis of the presence of ESBL and AmpC beta-lactamase genes.

Results: The qnr gene was detected in 47 of 347 clinical Enterobacteriaceae isolates. Among the 47 qnr-positive strains, Klebsiella pneumoniae (N=29) was the most common, followed by Escherichia coli (N=6), Enterobacter cloacae (N=6), Citrobacter freundii (N=5), and Enterobacter aerogenes (N=1). These isolates were identified as qnrA1 (N=6), 8 qnrB subtypes (N=40), and qnrS1 (N=1). At least 1 ESBL was detected in 38 of the 47 qnr-positive strains. Qnr-positive strains also showed high positive rates of ESBL or AmpC beta-lactamase, such as TEM, SHV, CTX-M, and DHA. DHA-1 was detected in 23 of 47 qnr-positive strains, and this was co-produced with 1 qnrA1 and 22 qnrB4. Strains harboring MIR-1T and CMY were also detected among the qnr-positive strains. Antimicrobial-resistance rates of qnr-positive strains to ciprofloxacin, levofloxacin, norfloxacin, nalidixic acid, and moxifloxacin were 51.1%, 46.8%, 46.8%, 74.5%, and 53.2%, respectively.

Conclusions: The qnr genes were highly prevalent in Enterobacteriaceae, primarily the qnrB subtypes. They were closely associated with EBSL and AmpC beta-lactamase.

Keywords: Beta-lactamase; Enterobacteriaceae; Qnr; Quinolone.

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Conflict of interest statement

No potential conflict of interest relevant to this article was reported.

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