Novel GES/IBC extended-spectrum beta-lactamase variants with carbapenemase activity in clinical enterobacteria

FEMS Microbiol Lett. 2004 May 15;234(2):209-13. doi: 10.1016/j.femsle.2004.03.028.


Two clinical isolates, an Escherichia coli and a Klebsiella pneumoniae, with decreased susceptibility to carbapenems were studied. This phenotype was associated with production of novel GES/IBC variant beta-lactamases, designated GES-3 (from E. coli) and GES-4 (from K. pneumoniae), exhibiting carbapenemase activity. Both enzymes possessed Ser at Ambler's position 170 instead of Gly found in the beta-lactamases GES-1 and IBC-1 that lack carbapenemase activity. Additionally, position 104 in GES-4 was occupied by a Lys as in IBC-1. bla(GES-3) and bla(GES-4) occurred as gene cassettes in the variable regions of class 1 integrons carried by plasmids. The structure of the GES-4-encoding integron was similar to that of previously described IBC-1 integrons. The GES-3-encoding integron was, most likely, truncated at the 3' conserved segment.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • DNA Primers
  • Drug Resistance, Bacterial / genetics
  • Enterobacteriaceae / enzymology*
  • Enterobacteriaceae / isolation & purification
  • Escherichia coli / drug effects
  • Escherichia coli / enzymology
  • Escherichia coli / isolation & purification
  • Humans
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / enzymology
  • Klebsiella pneumoniae / isolation & purification
  • Microbial Sensitivity Tests
  • Plasmids / genetics
  • beta-Lactamases / genetics*
  • beta-Lactamases / metabolism*


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • DNA Primers
  • beta-Lactamases
  • carbapenemase