Frequency of inhibitor-resistant TEM beta-lactamases in Escherichia coli isolates from urinary tract infections in France

J Antimicrob Chemother. 1994 Nov;34(5):707-14. doi: 10.1093/jac/34.5.707.


Over a six-month period in 1993, 2972 non-duplicated isolates of Escherichia coli causing urinary tract infections were collected in a French teaching hospital (n = 785) and in three private laboratories (n = 2187). The resistance rate to amoxycillin-clavulanate combination (MIC > 16 mg/l) was 25.0% in the hospital isolates and 10.0% in the community isolates. Respectively, 27.5% and 45.0% of hospital and community isolates resistant to amoxycillin-clavulanate exhibited an unusual beta-lactam resistance pattern, suggesting inhibitor-resistant TEM (IRT) beta-lactamase production. These isolates were highly resistant to amoxycillin-clavulanate (MIC90 > 1024 mg/L), but were susceptible to cephalosporins (MIC < 32 mg/L). Enzyme extracts of these IRT-producing strains focused at pI 5.2 (n = 100) or 5.4 (n = 53). DNA-DNA hybridization confirmed that the beta-lactamases involved in this resistance mechanism were TEM-1 derived and contained variations in the altered positions described in IRT enzymes. This study shows a total frequency of 4.9% of IRT-producing isolates among E. coli isolated from urine specimens.

MeSH terms

  • Amoxicillin / pharmacology
  • Amoxicillin-Potassium Clavulanate Combination
  • Clavulanic Acids / pharmacology
  • Drug Resistance, Microbial
  • Escherichia coli / drug effects
  • Escherichia coli / enzymology*
  • Urinary Tract Infections / microbiology*
  • beta-Lactamase Inhibitors*
  • beta-Lactamases


  • Clavulanic Acids
  • beta-Lactamase Inhibitors
  • Amoxicillin-Potassium Clavulanate Combination
  • Amoxicillin
  • beta-Lactamases
  • beta-lactamase TEM-1