Prevalence of SXT/R391-like integrative and conjugative elements carrying blaCMY-2 in Proteus mirabilis

J Antimicrob Chemother. 2011 Oct;66(10):2266-70. doi: 10.1093/jac/dkr286. Epub 2011 Jul 13.


Objectives: To characterize the vectors involved in the dissemination of bla(CMY-2) genes in clinical isolates of Proteus mirabilis collected between 1999 and 2007.

Methods: Plasmid analysis of 19 P. mirabilis carrying ampC genes was performed by PCR-based replicon typing, S1-PFGE and Southern hybridization with ampC and replicon probes. Isolates that could not be characterized were examined for the presence of SXT/R391-like elements. To demonstrate the involvement of these elements in the dissemination of bla(CMY-2), we performed a PCR amplification of the integrase (int) and toxin/antitoxin (TA) genes from SXT/R391-like integrative conjugative elements (ICEs). Later on, I-Ceu-I PFGE gels and hybridization with bla(CMY-2), int and prfC probes were performed. The genetic organization of bla(CMY-2) was also studied.

Results: ampC genes were located on large conjugative plasmids in 11 of the 19 (58%) P. mirabilis studied. However, in eight of these isolates a plasmid was not involved in the mobilization of ampC genes. I-Ceu-I PFGE and hybridization analyses revealed that bla(CMY-2) were chromosomally located in these eight P. mirabilis isolates. The genetic organization of bla(CMY-2) and hybridization analyses revealed that bla(CMY-2) was carried by an ICE almost identical to ICEPmiJpan1 in seven out of these eight isolates.

Conclusions: The prevalence of ICEs carrying bla(CMY-2) was surprisingly high [37% (7 out of 19)]. This is the first study giving prevalence data on ICEs carrying bla(CMY-2) genes. These results suggest the need to study these mobile genetic elements in the context of dissemination of acquired AmpC β-lactamases and also of other β-lactamases, such as extended-spectrum β-lactamases and carbapenemases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Conjugation, Genetic
  • DNA, Bacterial / genetics
  • Drug Resistance, Multiple, Bacterial / genetics
  • Humans
  • Integrases / genetics
  • Interspersed Repetitive Sequences*
  • Microbial Sensitivity Tests
  • Plasmids*
  • Proteus Infections / drug therapy
  • Proteus Infections / microbiology
  • Proteus mirabilis / genetics*
  • Proteus mirabilis / isolation & purification
  • beta-Lactamases / genetics*


  • Bacterial Proteins
  • DNA, Bacterial
  • Integrases
  • beta-lactamase CMY-2
  • AmpC beta-lactamases
  • beta-Lactamases