Activity of amoxycillin/clavulanate against beta-lactamase-producing Escherichia coli and Klebsiella spp

J Antimicrob Chemother. 1989 Nov;24 Suppl B:41-7. doi: 10.1093/jac/24.suppl_b.41.


We studied the susceptibility to the amoxycillin/clavulanate combination (2:1), and the characteristics of the beta-lactamases, of 1410 amoxycillin-resistant strains of Enterobacteriaceae (785 of Escherichia coli and 625 of Klebsiella spp.). Of the E. coli strains, 97.07% were susceptible to the combination and 98.85% produced plasmid-mediated beta-lactamases. Of the Klebsiella spp. strains, 87.84% were susceptible to the combination and 75.36% produced plasmid-mediated beta-lactamases. In both cases, the differences in MIC values, according to the characteristics of the beta-lactamases of the strains, were statistically significant. Of the 99 strains of E. coli and Klebsiella spp. that were not inhibited by amoxycillin 16 mg/l with clavulanate 8 mg/l, 19 hyperproduced chromosomal beta-lactamase; five produced a plasmid-type beta-lactamase as well. Fifty-seven strains produced two plasmid-type beta-lactamases.

MeSH terms

  • Amoxicillin / pharmacology*
  • Clavulanic Acids / pharmacology*
  • Drug Therapy, Combination / pharmacology
  • Escherichia coli / drug effects*
  • Escherichia coli / enzymology
  • Escherichia coli Infections / microbiology
  • Humans
  • Klebsiella / drug effects*
  • Klebsiella / enzymology
  • Klebsiella Infections / microbiology
  • Microbial Sensitivity Tests
  • Penicillin Resistance
  • beta-Lactamases / biosynthesis*


  • Clavulanic Acids
  • Amoxicillin
  • beta-Lactamases