title: Susceptibility of anaerobic bacteria to ten antimicrobial agents.
abstract: The susceptibility pattern of 265 anaerobic bacteria from clinical isolates to 10 antimicrobial agents was investigated by the agar dilution technique. Penicillin G, in a concentration of 16 mug/ml, was active against most organisms, important exceptions being 12% of Bacteroides melaninogenicus and 24% of B. fragilis strains. The susceptibility of strains to ampicillin was similar to their susceptibility to penicillin G. Carbenicillin, at </=128 mug/ml, inhibited all but a few strains. Cefamandole was less active than the penicillins; 82% of B. melaninogenicus, 32% of B. fragilis, and 75% of Fusobacterium strains were inhibited by </=16 mug/ml. A trend towards tetracycline resistance was seen in many bacterial groups, especially Bacteroides, Fusobacterium, and Clostridium. All organisms were susceptible to chloramphenicol and clindamycin in concentrations of </=16 mug/ml and </=4 mug/ml, respectively. Erythromycin was less active than clindamycin against all strains tested. Metronidazole and tinidazole were active against most anaerobes, but resistance of a few strains in each group was encountered. The increased resistance of B. melaninogenicus strains to penicillin, and emergence of anaerobes resistant to >16 mug of imidazole per ml may have therapeutic implications.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D004352:Drug Resistance, Microbial
chemical_list: D000900:Anti-Bacterial Agents