Metallo-beta-lactamase-producing Enterobacteriaceae isolates in a university hospital in Taiwan: prevalence of IMP-8 in Enterobacter cloacae and first identification of VIM-2 in Citrobacter freundii

J Antimicrob Chemother. 2002 Oct;50(4):503-11. doi: 10.1093/jac/dkf170.


A total of 9082 clinical isolates of Enterobacteriaceae other than Klebsiella spp. collected in 1999 and 2000 at a university hospital in Taiwan were investigated for the production of metallo- beta-lactamases (MBLs). Thirty-six (2.9%) of the 1261 Enterobacter cloacae isolates and one (0.3%) of the 340 Citrobacter freundii isolates were found to carry bla(IMP-8) and bla(VIM-2), respectively, by colony hybridization, PCR and sequence analysis. The IMP-8 producers were recovered from 20 patients and four of them had recently transferred from other hospitals, implying spread of IMP-8-producing E. cloacae among different healthcare settings. Of the 20 non-repetitive IMP-8 producers, 17 (85%) isolates also harboured bla(SHV-12), which was on the same transferable plasmids with bla(IMP-8). The bla(VIM-2)-positive isolate and all non-repetitive bla(IMP-8)-positive isolates appeared susceptible to imipenem (MICs < 8 mg/L) and meropenem (MICs < 4 mg/L), indicating the difficulty in detection of MBLs in Enterobacteriaceae by routine susceptibility testing. Ribotyping of the IMP-8-producing E. cloacae isolates indicated that the dissemination of bla(IMP-8) was due largely to the spread of an epidemic clone, but horizontal transfer among unrelated strains also occurred.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Citrobacter freundii / enzymology*
  • Citrobacter freundii / genetics
  • Citrobacter freundii / isolation & purification
  • Enterobacter cloacae / enzymology*
  • Enterobacter cloacae / genetics
  • Enterobacter cloacae / isolation & purification
  • Enterobacteriaceae / enzymology
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / isolation & purification
  • Hospitals, University / statistics & numerical data
  • Humans
  • Microbial Sensitivity Tests / statistics & numerical data
  • Taiwan / epidemiology
  • beta-Lactamases / biosynthesis*
  • beta-Lactamases / genetics


  • IMP-8 enzyme
  • VIM-2 beta-lactamase
  • beta-Lactamases