Susceptibility of anaerobic bacteria to antimicrobial agents.
The antimicrobial susceptibility of 1,117 clinical isolates of anaerobic bacteria was determined by the agar dilution technique. Metronidazole was the most active agent; only Propionibacterium acnes and Actinomyces sp. isolates were resistant. Clindamycin and chloramphenical were the next most effective agents. Beta-lactam antibiotics, with the exception of penicillin, were active against most anaerobes other than the Bacteroides fragilis group. At a breakpoint of 8 mg/l, 25% of Fusobacterium spp. and 30% of the non-fragilis Bacteroides spp. were resistant to penicillin. The highest resistance to beta-lactams was seen in the B. fragilis group. Within the indole-positive members of the group, resistance rates of 71% were seen for cefoxitin, 49% for moxalactam, 79% for cefotaxime, 22% for piperacillin and 89% for penicillin. We conclude that metronidazole has the most predictable in vitro activity against common clinical anaerobic isolates and that resistance to beta-lactams was frequent and of potential clinical importance as these latter agents are frequently used in the prophylaxis and therapy of mixed anaerobic infections.
Collignon
P J
PJ
Bacteriology Department, Westmead Hospital, Sydney.
Munro
R
R
Morris
G
G
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001421:Bacteria, Anaerobic / Q000187:drug effects* / Q000302:isolation & purification; D001439:Bacteroides / Q000187:drug effects / Q000302:isolation & purification; D004352:Drug Resistance, Microbial; D006801:Humans; D007769:Lactams; D008795:Metronidazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests
D000900:Anti-Bacterial Agents; D007769:Lactams; D008795:Metronidazole