Molecular epidemiology of CTX-M-producing Escherichia coli isolates at a tertiary medical center in Western Pennsylvania

Hanna E. Sidjabat, David L. Paterson, Jennifer M. Adams-Haduch, Lindsay Ewan, Anthony W. Pasculle, Carlene A. Muto, Guo Bao Tian, Yohei Doi

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107 Citations (Scopus)


A combination of phenotypic and genotypic methods was used to investigate 70 unique Escherichia coli clinical isolates identified as producing extended-spectrum β-lactamases (ESBLs) at a medical center in Pittsburgh, PA, between 2007 and 2008. Fifty-seven isolates (81%) produced CTX-M-type ESBLs, among which CTX-M-15 was predominant (n = 46). Isolates producing CTX-M-2, -9, -14, and -65 were also identified. One CTX-M-producing isolate coproduced CMY-2 cephalosporinase. Ten isolates (14%) produced SHV-type ESBLs, either SHV-5 or SHV-7. Two isolates produced only CMY-2 or -32. Pulsed-field gel electrophoresis revealed the presence of two major clusters of CTX-M-15-producing E. coli isolates, one in phylotype B2 (n = 15) and the other in phylotype A (n = 19). Of four phylotype B2 isolates that were able to transfer the bla CTX-M-15-carrying plasmids, three showed fingerprints related (>60%) to those of plasmids from phylotype A isolates. In phylotype B2, all CTX-M-15-producing isolates, as well as three isolates producing CTX-M-14, two producing SHV-5, and one producing SHV-7, belonged to the international epidemic clone defined by serotype O25:H4 and sequence type 131. The plasmids from eight of nine CTX-M-15-producing E. coli isolates of phylotype A that were examined were highly related to each other and were also found in two isolates belonging to phylotype D, suggesting horizontal transfer of this blaCTX-M-15- carrying plasmid between phylotypes. Our findings underscore the need to further investigate the epidemiology and virulence of CTX-M-producing E. coli in the United States.

Original languageEnglish
Pages (from-to)4733-4739
Number of pages7
JournalAntimicrobial agents and chemotherapy
Issue number11
Publication statusPublished - 11-2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases


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