Anaerobes: taxonomy and antibiotic patterns.

Phenotypic characteristics allow the identification of gram negative anaero bes. On many occasions they belong to one of the following groups: Bacteroi des fragilis group, Prevotella, Porphyromonas and Fusobacterium. Thus this classification may link on the one hand the bacterial identification and on the other the source of the strains (oral or fecal flora), the diseases th ey cause and the empirical therapy. If recent nucleic analysis (DNA-DNA hyb ridization and 16S RNA sequencing) has improved the phylogenetic relatednes s between species, if disturbs physicians and clinicians in their daily pra ctice. Combinations of penicillins and beta-lactamase inhibitors allow one to keep the excellent activity of penicillins on gram positive anaerobes and to by pass the beta-lactamase production observed frequently among Prevotella or; rarely, among Fusobacterium. Among the anaerobic species, strains of the B acteroides fragilis group are more resistant to many antibiotics; their res istance rates have been increasing for 15 years, mainly for cefotetan and c lindamycin. Routine susceptibility testing and periodical surveys are obvio usly needed. (C) 2000 Editions scientifiques et medicales Elsevier SAS.