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

Wonkeun Song, Juwon Kim, Il Kwon Bae, Seok Hoon Jeong, Young Hee Seo, Jong Hee Shin, Sook Jin Jang, Young Uh, Jeong Hwan Shin, Mi Kyung Lee, Kyungwon Lee

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51 Citations (Scopus)


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 blaCTX-M-90 (n = 4), bla CTX-M-15 (n = 3), blaCTX-M-12 (n = 3), bla CTX-M-2 (n = 2), blaCTX-M-14b (n = 1), bla TEM-52 (n = 5), and blaSHV-12 (n = 1) genes were also detected. Eight isolates carried an AmpC β-lactamase gene, such as bla CMY-2 (n = 6) or blaDHA-1 (n = 2). All bla genes encoding CTX-M-1- and CTX-M-9-type enzymes and all blaCMY-2 genes were preceded by ISEcp1-like elements. The blaCTX-M-2 gene found in two isolates was located on a complex class 1 integron. The blaDHA-1 gene was preceded by a transcriptional regulator gene and was followed by phage shock protein genes. The blaCTX-M genes were located on the chromosome in 21 isolates. A plasmid location for the blaCTX-M gene was found in only four isolates: the blaCTX-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 blaTEM-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 blaCMY-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.

Original languageEnglish
Pages (from-to)1414-1419
Number of pages6
JournalAntimicrobial agents and chemotherapy
Issue number4
Publication statusPublished - 2011 Apr

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases


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