Prevalence of quinolone resistance determinant qnrA6 among broad- and extended-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates with sul1-type class 1 integron association in a Tunisian Hospital

Scand J Infect Dis. 2013 Aug;45(8):600-5. doi: 10.3109/00365548.2013.795657. Epub 2013 Jun 9.

Abstract

Objectives: The aim of this study was to investigate the prevalence and the emergence of plasmid-mediated quinolone resistance among broad-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates recovered in the Military Hospital in Tunisia.

Methods: Of 200 strains examined, 50 exhibited resistance to quinolones. Quinolone resistance determinants (qnr and aac(6')-Ib-cr) were characterized by multiplex PCR and sequencing. Chromosomal quinolone resistance mutations in the quinolone resistance-determining region (QRDR) and class 1 integron characterization were analysed by PCR and sequencing. The clonal relationship between the isolates was studied by pulsed-field gel electrophoresis (PFGE).

Results: Fourteen isolates harboured qnrA6 and among them 8 (57%) were extended-spectrum beta-lactamase (ESBL) producers, whilst 12 (85%) isolates harboured blaDHA-1. Mutations in the QRDR were detected in gyrA (Ser83Ile, Glu87Lys), gyrB (Ser464Phe), and parC (Ser80Ile). qnrA6 and blaDHA-1 genes were found embedded in complex sul1-type class 1 integrons. A gene cassette carrying aac(6')-Ib-cr was found located in the class 1 integron upstream of the qacEΔ1 gene. According to the PFGE analysis, the isolates were clonally unrelated.

Conclusions: This is the first description in North Africa of class 1 integrons carrying blaDHA-1, qnrA6 gene, and aac(6')-Ib-cr determinants in clinical strains of Proteus mirabilis and Morganella morganii.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Anti-Bacterial Agents / pharmacology*
  • DNA, Bacterial / genetics
  • Drug Resistance, Bacterial*
  • Electrophoresis, Gel, Pulsed-Field
  • Enterobacteriaceae Infections / microbiology*
  • Female
  • Genes, Bacterial*
  • Hospitals, Military
  • Humans
  • Integrons
  • Male
  • Middle Aged
  • Molecular Typing
  • Morganella morganii / classification
  • Morganella morganii / drug effects
  • Morganella morganii / genetics*
  • Morganella morganii / isolation & purification
  • Plasmids
  • Polymerase Chain Reaction
  • Proteus mirabilis / classification
  • Proteus mirabilis / drug effects
  • Proteus mirabilis / genetics*
  • Proteus mirabilis / isolation & purification
  • Quinolones / pharmacology*
  • Sequence Analysis, DNA
  • Tunisia
  • beta-Lactams / pharmacology

Substances

  • Anti-Bacterial Agents
  • DNA, Bacterial
  • Quinolones
  • beta-Lactams