In vitro activity of U-57930E against anaerobic bacteria and its comparison with clindamycin, ampicillin, carbenicillin and tetracycline.

The in vitro activity of U-57930E, a pipecolic acid amide of clindamycin, was compared with those of clindamycin, ampicillin, carbenicillin and tetracycline against 321 anaerobic clinical isolates. The MIC (micrograms/ml) of U-57930E that inhibited 95% Bacteroides fragilis, Peptococcus prevotii, B. melaninogenicus and P. asaccharolyticus was 0.0625; 0.03125 for Peptostreptococcus anaerobius, B. vulgatus, Propionibacterium and Peptococcus species. Clindamycin, on the other hand, gave MIC values of 0.5 microgram/ml for B. fragilis, P. prevotii and P. asaccharolyticus, 0.25 for Propionibacterium sp. All strains of Clostridium perfringens were inhibited by 0.5 microgram/ml of U-57930E. Both clindamycin and U-57930E showed similar MIC values for all strains of Fusobacterium nucleatum and Propionibacterium acnes tested. The MIC values for ampicillin, carbenicillin and tetracycline were within the expected range. U-57930E had a 4 approximately 8 fold lower MIC than clindamycin and is significantly active against anaerobic bacteria.