Antibiotic susceptibility of Escherichia coil strains isolated in 1998 and1999: results of a French multicenter study.

Objective - Seven hospital lab departments were enrolled in this study in o rder to update and analyse data on E. coli susceptibility to antibiotics in 1998 and 1999. Material and methods - 1,114 strains were randomly selected for analysis, a large number of which had been obtained from female (65,7%) and elderly pa tients, and essentially from urinary samples (56%) and blood cultures (23%) . Results - It was observed that resistance rates (R+I) were elevated for amo xicillin (44%), ticarcillin (42%), co-amoxiclav (31%) and cephalothin (36%) , moderate for nalidixic acid (8%), ciprofloxacin (5%) and gentamicin (2%), and very low for ceftazidime (1%) and ceftriaxone (0.8%); 2 strains only ( 0.2%) were ESBL producers. Finally, it was noteworthy that pediatry units w ere providers of strains significantly more resistant to amoxicillin, co-am oxiclav, ticarcillin and cephalothin than strains from other units; no othe r risk-factor of resistance was detected. While the previous 1 114 randomis ed strains presented MIC50 and 90 of 0.125 and 0.25 g mu /mL for ceftazidim e and 0,03 and 0,06 mug/mL for ceftriaxone, a complementary analysis carrie d out on a pool of 76 ESBL producers and 137 strains resistant (R+I) to cef tazidime and/or to cefotaxime/cefriaxone (but ESBL-) revealed that these va lue were increased of 7 to 9 dilutions for the 76 ESBL+ strains and of 5 to 6 for the 137 ESBL- strains in comparison with susceptible strains. Moreov er these strains were observed to present elevated rates of co-resistance ( R+I) to nalidixic acid, ciprofloxacin and gentamicin: 52%, 37% and 41% resp ectively for ESBL+ strains and 43%, 21% and 16% respectively for ESBL- stra ins. (C) 2000 Editions scientifiques ef medicales Elsevier SAS.