Frequency of inhibitor-resistant TEM β-lactamases in Escherichia coli isolates from urinary tract infections in Fran

• Published in: Journal of antimicrobial chemotherapy 1994-11, Vol.34 (5), p.707-714
• Main Authors: Henquell, C., Sirot, D., Chanal, C., Champs, C. De, Chatron, P., Lafeuille, B., Texier, P., Sirof, J., Cluzel, R.
• Format: Article
• Language: English
• ISSN: 0305-7453; 1460-2091
• 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 > 16mg/l) was 25.0% in the hospital isolates and 100% in the community isolates. Respectively, 27.5% and 45.0% of hospital and community isolates resistant to amoxycillin-clavulanate exhibited an unusual β-lactam resistance pattern, suggesting inhibitor-resistant TEM (IRT) >-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 β-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.