Mutations in the ampC Promoter of Escherichia Coli Isolates Resistant to Oxyiminocephalosporins Without Extended Spectrum Beta-Lactamase Production

FEMS Microbiol Lett. 1999 Apr 15;173(2):459-65. doi: 10.1111/j.1574-6968.1999.tb13539.x.

Abstract

Escherichia coli strains showing an increased resistance to oxyiminocephalosporins without an extended spectrum beta-lactamase production have been screened for mutations in their ampC beta-lactamase gene promoter. Mutations were found by direct sequencing of seven promoters at positions -42, -32 (box -35), -18, -1, +5, +24 (attenuator), +31 (attenuator) and +58. By using rapid and simple methods, three of these mutations (-42, -32 and +24), which could enhance transcription, were searched in 37 resistant and 25 sensitive isolates. The -42 mutation was present in 33 of the 37 promoters from the resistant isolates. The -32 and +24 mutations were present only in three and two promoters, respectively, and they were combined in the most resistant strain of the study. The +24 mutation was detected in another strain associated with a 1-bp insertion between the -35 and -10 conserved sequences. None of these mutations was detected in the ampC beta-lactamase from the sensitive isolates.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins*
  • Base Sequence
  • Cefoxitin / pharmacology
  • Cephalosporin Resistance / genetics*
  • Cephalosporins / pharmacology
  • Cephamycins / pharmacology
  • Escherichia coli / drug effects
  • Escherichia coli / genetics*
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / microbiology
  • Humans
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Mutation*
  • Promoter Regions, Genetic / genetics*
  • Sequence Analysis, DNA
  • beta-Lactamases / biosynthesis
  • beta-Lactamases / genetics*

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Cephalosporins
  • Cephamycins
  • Cefoxitin
  • AmpC beta-lactamases
  • beta-Lactamases