[In vitro activity of the amoxicillin-clavulanic acid combination on anaerobic bacteria. Comparison with amoxicillin, lamoxactam and metronidazole].

Minimal inhibitory concentrations (MIC) of the combination amoxicillin + clavulanic acid (AAC) (2/1 w/w) on 84 strains of obligate anaerobes were measured by the agar diffusion method and compared to those of amoxicillin (AMO), lamoxactam (LAM) and metronidazole (MET). For the 47 Bacteroides fragilis strains tested, the mode MIC was 0.5 microgram/ml with AAC, 1-2 with MET, 0.5-1 with LAM and 8-16 with AMO. A similar range of activity was found on the 16 other strains of Bacteroides sp.. AAC and AMO have a comparable activity on Clostridium perfringens (mode MIC 0.016-0.032 microgram/ml), superior to that of LAM (mode MIC 0.125) and MET (mode MIC 0.5). AAC and AMO have an almost identical activity on Peptococci and Peptostreptococci, the MIC for both drugs being less than 0.125 microgram/ml. A similar activity was found for LAM and MET.