Characterization of carbapenem-non-susceptible Escherichia coli isolates from a university hospital in Taiwan

Yi Fang Liu, Jing Jou Yan, Wen Chien Ko, Shu Huei Tsai, Jiunn Jong Wu

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Abstract

Objectives: To investigate characteristics of nine carbapenem-non-susceptible (CP-NS) Escherichia coli isolates collected between 1999 and 2005 at a Taiwanese university hospital. Methods: Genetic relatedness was analysed by PFGE. β-Lactamases were characterized by PCR and isoelectric focusing. Outer membrane proteins and transcripts were investigated by SDS-PAGE and northern blotting. Cloning experiments were performed to investigate the role of membrane permeability in carbapenem non-susceptibility. Results: The nine CP-NS isolates were found to produce the CMY-2 AmpC enzyme (n=8), the CTX-M-14-type extended-spectrum β-lactamase (ESBL) (n=1), the SHV-12 ESBL (n=1) and the IMP-8-type metallo-β-lactamase (n=1) alone or in combination. All CP-NS isolates revealed a decrease in the transcription and protein expression of ompC, and susceptibility to carbapenems was restored in one isolate by introducing the cloned ompC gene. PFGE revealed genetic diversity among the nine isolates. All patients with the CP-NS isolates had been treated with carbapenems (six patients) and/or extended-spectrum cephalosporins (five patients) before isolation. Conclusions: Our study suggests that the decreased susceptibility to carbapenems in E. coli in the hospital might arise by the stepwise accumulations of multiple drug-resistance determinants in different clones.

Original languageEnglish
Pages (from-to)1020-1023
Number of pages4
JournalJournal of Antimicrobial Chemotherapy
Volume61
Issue number5
DOIs
Publication statusPublished - 2008 May 1

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

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