[In vitro activity of 10 antibiotics including pristinamycin and its two components (RP 12536 and 27404) against strict anaerobes].

The activities of the pristinamycin and its two components (RP 12536 and RP 27404) were investigated using the reference agar dilution method M11A3, on 175 anaerobic strains in comparison with that of erythromycin, clindamycin, metronidazole, amoxycillin either alone or combined with clavulanic acid, piperacillin, cefoxitin, cefotetan and cefotaxime. beta-lactamase production was detected for all the 55 B. fragilis group strains and 8/12 Prevotella and 2/18 Fusobacterium strains, respectively. On the whole anaerobes, resistance rates (%) were respectively: RP 27404 (69), RP 12536 (64), pristinamycin (5) erythromycin (31), clindamycin (17), metronidazole (7) amoxycillin (24), amoxycillin-clavulanic acid (2), piperacillin (7), cefoxitin (14), cefotetan (21) and cefotaxime (27). RP 27404 and 12536 had low activities on anaerobes but acted synergistically as pristinamycin. The greatest anti-anaerobic potencies were obtained with amoxycillin-clavulanic acid combination, pristinamycin, metronidazole and piperacillin. As resistance was not found for pristinamycin among Prevotella, Fusobacterium, Gram+ rods and Peptostreptococcus, this streptogramin may be an appropriate agent for the treatment of periodontitis, pulmonary, ENT, gynecologic and soft tissue infections where these anaerobes are frequently involved.