Accumulation of plasmid-mediated fluoroquinolone resistance genes, qepA and qnrS1, in Enterobacter aerogenes co-producing RmtB and class A beta-lactamase LAP-1

Ann Clin Lab Sci. 2009 Winter;39(1):55-9.

Abstract

A new plasmid-mediated fluoroquinolone efflux pump gene, qepA, is known to be associated with the rmtB gene, which confers high-level resistance to aminoglycosides. We investigated the qepA gene in 573 AmpC-producing Enterobacteriaceae including one Citrobacter freundii known to harbor rmtB. Of them, two clonally unrelated E. aerogenes harbored qepA. Both isolates co-harbored rmtB, qnrS1, qepA, and bla(LAP-1) on an IncFI type plasmid. The qepA was flanked by two copies of IS26 containing ISCR3C, tnpA, tnpR, bla(TEM), and rmtB. The qnrS1 and bla(LAP-1) were located upstream of qepA. All the resistance determinants (qepA, qnrS1, rmtB, and bla(LAP-1)) were co-transferred to E. coli J53 by filter mating from both isolates. Although the prevalence of qepA is currently low, considering the presence of ISCR3C and the possibility of co-selection and co-transferability of plasmids, more active surveillance for these multi-drug resistant bacteria and prudent use of antimicrobials are needed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Conjugation, Genetic / drug effects
  • Drug Resistance, Bacterial / drug effects
  • Drug Resistance, Bacterial / genetics*
  • Enterobacter aerogenes / drug effects
  • Enterobacter aerogenes / enzymology*
  • Enterobacter aerogenes / genetics*
  • Fluoroquinolones / pharmacology*
  • Genes, Bacterial*
  • Microbial Sensitivity Tests
  • Plasmids / genetics*
  • beta-Lactamases / metabolism*

Substances

  • Anti-Bacterial Agents
  • Fluoroquinolones
  • beta-Lactamases