Chromosome-encoded AmpC and CTX-M extended-spectrum β-lactamases in clinical isolates of Proteus mirabilis from Korea

Antimicrob Agents Chemother. 2011 Apr;55(4):1414-9. doi: 10.1128/AAC.01835-09. Epub 2011 Jan 31.

Abstract

Among 222 Proteus mirabilis clinical isolates collected from 17 hospitals in Korea in 2008, 28 (12.6%) and 8 (3.6%) isolates exhibited extended-spectrum β-lactamase (ESBL) and AmpC phenotypes, respectively. The most common type of ESBL gene identified by PCR and sequencing experiments was bla(CTX-M-14a) (n = 12). The bla(CTX-M-90) (n = 4), bla(CTX-M-15) (n = 3), bla(CTX-M-12) (n = 3), bla(CTX-M-2) (n = 2), bla(CTX-M-14b) (n = 1), bla(TEM-52) (n = 5), and bla(SHV-12) (n = 1) genes were also detected. Eight isolates carried an AmpC β-lactamase gene, such as bla(CMY-2) (n = 6) or bla(DHA-1) (n = 2). All bla genes encoding CTX-M-1- and CTX-M-9-type enzymes and all bla(CMY-2) genes were preceded by ISEcp1-like elements. The bla(CTX-M-2) gene found in two isolates was located on a complex class 1 integron. The bla(DHA-1) gene was preceded by a transcriptional regulator gene and was followed by phage shock protein genes. The bla(CTX-M) genes were located on the chromosome in 21 isolates. A plasmid location for the bla(CTX-M) gene was found in only four isolates: the bla(CTX-M-14a) gene was located on ∼150-kbp IncA/C plasmids in three isolates and on a ∼50-kbp IncN plasmid in one isolate. The bla(TEM-52) gene was located on ∼50-kbp IncN plasmids in all five isolates. The AmpC β-lactamase genes were located on the chromosome in seven of eight isolates; one isolate carried the bla(CMY-2) gene on a ∼150-kbp IncA/C plasmid. Our results show that a chromosomal location of CTX-M ESBL and AmpC β-lactamase genes in P. mirabilis is no longer an unusual phenomenon in hospital environments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / genetics*
  • Blotting, Southern
  • Chromosomes, Bacterial / genetics*
  • Clavulanic Acid / pharmacology
  • Korea
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Plasmids / genetics
  • Polymerase Chain Reaction
  • Proteus mirabilis / drug effects
  • Proteus mirabilis / enzymology*
  • Proteus mirabilis / genetics
  • beta-Lactamases / genetics*

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Clavulanic Acid
  • AmpC beta-lactamases
  • beta-Lactamases

Associated data

  • GENBANK/GU065288