Transferable class C beta-lactamases in Escherichia coli strains isolated in Greek hospitals and characterization of two enzyme variants (LAT-3 and LAT-4) closely related to Citrobacter freundii AmpC beta-lactamase

J Antimicrob Chemother. 1998 Oct;42(4):419-25. doi: 10.1093/jac/42.4.419.


Among 2133 isolates of Escherichia coli obtained during 1996 from 10 Greek hospitals, 63 (3%) were resistant to cefoxitin. Typing by ERIC2-PCR indicated that the cefoxitin-resistant (FOXr) isolates were distinct. beta-Lactamase studies and hybridization experiments showed that most strains produced beta-lactamases related to the AmpC chromosomal cephalosporinase of Citrobacter freundii. The enzymes were encoded by similar non-self-transmissible plasmids. The bla genes encoding two beta-lactamases (LAT-3 and LAT-4) with isoelectric points 8.9 and 9.4, respectively, were cloned and sequenced. The deduced amino acid sequences displayed a high degree of homology (>95%) with the AmpC beta-lactamase of C. freundii. The patterns of resistance to beta-lactams of the FOXr E. coli depended on the quantity of class C enzymes and the simultaneous expression of other beta-lactamases. In a few isolates a 36 kDa outer-membrane protein, presumably a porin, was not expressed at detectable quantities. These isolates were resistant to cefoxitin, and their susceptibility to the other beta-lactams tested was not significantly decreased.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Outer Membrane Proteins / metabolism
  • Bacterial Proteins*
  • Base Sequence
  • Cefoxitin / therapeutic use
  • Cephamycins / therapeutic use
  • Citrobacter freundii / enzymology*
  • Citrobacter freundii / genetics
  • Cloning, Molecular
  • Drug Resistance, Microbial
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli / drug effects
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Escherichia coli Proteins*
  • Gene Transfer Techniques
  • Greece
  • Humans
  • Hydrolysis
  • Isoelectric Focusing
  • Isoenzymes / metabolism
  • Molecular Sequence Data
  • Nucleic Acid Hybridization
  • Plasmids
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism*


  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Cephamycins
  • Escherichia coli Proteins
  • Isoenzymes
  • Cefoxitin
  • beta-lactamase LAT-3 protein, E coli
  • beta-lactamase LAT-4 protein, E coli
  • AmpC beta-lactamases
  • beta-Lactamases

Associated data

  • GENBANK/Y15411
  • GENBANK/Y15412