The ACT-1 Plasmid-Encoded AmpC Beta-Lactamase Is Inducible: Detection in a Complex Beta-Lactamase Background

J Antimicrob Chemother. 2002 Mar;49(3):557-60. doi: 10.1093/jac/49.3.557.


The purpose of this study was to identify the genetic organization and inducibility of bla(ACT-1) in a clinical isolate of Klebsiella pneumoniae possessing at least five different beta-lactamases. The genetic organization of the bla(ACT-1)/ampR region is identical to those of inducible chromosomal ampC genes. RNA analysis using primer extension demonstrated a five-fold increase in bla(ACT-1) transcript production on exposure to cefoxitin. These findings are significant because induction was detected in a complicated beta-lactamase background. In addition, this report is the first to describe an inducible plasmid-encoded AmpC beta-lactamase of Enterobacter cloacae origin.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Proteins*
  • Cefoxitin / pharmacology*
  • DNA, Bacterial / analysis
  • Enzyme Induction
  • Genes, Bacterial*
  • Klebsiella pneumoniae / drug effects
  • Klebsiella pneumoniae / enzymology
  • Klebsiella pneumoniae / genetics*
  • Plasmids
  • Polymerase Chain Reaction
  • RNA, Bacterial / analysis
  • beta-Lactamases / biosynthesis
  • beta-Lactamases / genetics*


  • Bacterial Proteins
  • DNA, Bacterial
  • RNA, Bacterial
  • Cefoxitin
  • AmpC beta-lactamases
  • beta-Lactamases