RESISTANCE TO ANTIBIOTICS IN THE BACTEROI DES-FRAGILIS GROUP - STUDY BY MICS AND KINETICS OF INHIBITORY QUOTIENTS

The Groupe d'Etudes Epidemiologiques et Prophylactiques (GEEP) and the College de Bacteriologie, Virologie et Hygiene des Hopitaux Generaux (Col BVH) have organized, in 1991 and 1992, nationwide surveys of anti biotic susceptibility of clinical isolates of the Bacteroides fragilis group. The aim of these investigations was to evaluate the efficacy o f commonly used antimicrobial agents against anaerobic pathogens, and to predict the possible evolution of antibiotic susceptibility pattern s. For strains isolated from blood cultures, MICs of 20 antibiotics ha ve been determined, with, in addition, nine beta-lactamine - beta-lact amase inhibitor (beta1-I) combinations. In order to better appreciate the in vivo activity of the beta-1 combinations, kinetics of inhibitor y quotients (IQ) have been established, based on free serum concentrat ions of the beta-lactam antibiotics. IQ kinetics allowed the assigneme nt of the beta-1 combinations tested into three groups, with apparentl y favorable IQs for group 1 (ticarcillin/clavulanic acid) and group 2 (amoxicillin/clavulanic acid and piperacillin/tazobactam or sulbactam) , but maybe less favorable IQs for group 3 (ceftazidime/sulbactam).