Characterization of blaCMY-10 a novel, plasmid-encoded AmpC-type beta-lactamase gene in a clinical isolate of Enterobacter aerogenes

J Appl Microbiol. 2003;95(4):744-52. doi: 10.1046/j.1365-2672.2003.02040.x.

Abstract

Aims: We report the description of a novel plasmid-encoded AmpC beta-lactamase gene (blaCMY-10) from Enterobacter aerogenes K9911729 that was isolated from a patient suffering from pneumonia in South Korea.

Methods and results: Using antibiotic susceptibility testing, plasmid analysis, transconjugation and Southern blot analysis, the cefoxitin resistance phenotype reflects the presence of a large plasmid [pYMG-1 (130 kb)] in Ent. aerogenes K9911729. One beta-lactamase with the pI of 8.0 from transconjugant of Ent. aerogenes K9911729 was identified by isoelectric focusing on a gel. A 1475 bp DNA fragment containing the blaCMY-10 gene, identified on pYMG-1 of Ent. aerogenes K9911729, was sequenced and an open reading frame coding for 382 amino acid, CMY-10, was found. The 37 class C beta-lactamases were subclassified into 1a to 1j and CMY-10 into 1a by phylogenetic analysis. A sequence identical to the common regions in In6, In7 and a novel integron from pSAL-1 was found upstream from blaCMY-10 gene at nucleotide 1-71.

Conclusions: These results clearly show that blaCMY-10 gene belongs to the group of ampC-related bla genes. Homology analysis among AmpC enzymes or ampC genes implied that integration of the chromosomal ampC gene into a large resident plasmid, followed by transconjugation, was involved in the evolution of blaCMY-10 gene.

Significance and impact of the study: The first identification of the blaCMY-10 gene is of concern as chromosomal beta-lactamases may cause serious therapeutic problems if their genes are translocated onto plasmids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Blotting, Southern / methods
  • Cefoxitin
  • Conjugation, Genetic
  • Drug Resistance, Bacterial
  • Enterobacter aerogenes / classification
  • Enterobacter aerogenes / genetics*
  • Humans
  • Isoelectric Focusing / methods
  • Phylogeny
  • Plasmids / genetics
  • Pneumonia / microbiology
  • Polymerase Chain Reaction / methods
  • beta-Lactamases / genetics*

Substances

  • Cefoxitin
  • beta-Lactamases