Journal Article

Emergence of plasmid-mediated resistance to quinolones in Enterobacteriaceae

Patrice Nordmann and Laurent Poirel

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 56, issue 3, pages 463-469
Published in print September 2005 | ISSN: 0305-7453
Published online July 2005 | e-ISSN: 1460-2091 | DOI:
Emergence of plasmid-mediated resistance to quinolones in Enterobacteriaceae

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Although quinolone resistance results mostly from chromosomal mutations in Enterobacteriaceae, it may also be mediated by plasmid-encoded Qnr determinants. Qnr proteins protect DNA from quinolone binding and compromise the efficacy of quinolones such as nalidixic acid. Qnr proteins (QnrA-like, QnrB and QnrS) have been identified worldwide with a quite high prevalence among Asian isolates with a frequent association with clavulanic acid inhibited expanded-spectrum β-lactamases and plasmid-mediated cephalosporinases. The qnrA genes are embedded in complex sul1-type integrons. A very recent identification of the origin of QnrA determinants in the water-borne species Shewanella algae underlines the role of the environment as a reservoir for this emerging threat. It may help to determine the location of in vivo transfer of qnrA genes. Further analysis of the role (if any) of quinolones for enhancing this gene transfer may be conducted. This could prevent the spread, if still possible, of this novel antibiotic resistance mechanism.

Keywords: nalidixic acid; Qnr; fluoroquinolones

Journal Article.  4734 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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