Emergence of imipenem resistance in Klebsiella pneumoniae owing to combination of plasmid-mediated CMY-4 and permeability alteration

J Antimicrob Chemother. 2000 Dec;46(6):895-900. doi: 10.1093/jac/46.6.895.


Klebsiella pneumoniae BM2974 isolated from an abdominal abcess was resistant to high concentrations of all available beta-lactams, including recently developed third-generation cephalosporins and carbapenems. Isoelectric focusing of beta-lactamases and amplification, cloning and sequencing of the corresponding genes, together with conjugation and transformation experiments, indicated that, in addition to the chromosomally encoded beta-lactamase, the strain produced three plasmid-mediated beta-lactamases with pIs of 5.4, 8.2 and 9.0, which corresponded to TEM-1, SHV-5 and AmpC-type CMY-4, respectively. Strain BM2974 also lacked a major outer membrane protein of c. 40 kDa which was present in the spontaneous imipenem-susceptible revertant BM2974-1. We suggest that imipenem resistance in strain BM2974 is attributable to production of CMY-4 beta-lactamase combined with permeability alteration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / analysis
  • Bacterial Proteins*
  • Conjugation, Genetic
  • Drug Resistance, Microbial
  • Imipenem / pharmacology*
  • Klebsiella pneumoniae / drug effects*
  • Klebsiella pneumoniae / genetics
  • Klebsiella pneumoniae / metabolism
  • Microbial Sensitivity Tests
  • Polymerase Chain Reaction
  • Thienamycins / pharmacology*
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism


  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Thienamycins
  • Imipenem
  • AmpC beta-lactamases
  • beta-Lactamases