ACTIVITY OF CP 99,219 COMPARED WITH THOSE OF CIPROFLOXACIN, GREPAFLOXACIN, METRONIDAZOLE, CEFOXITIN, PIPERACILLIN, AND PIPERACILLIN-TAZOBACTAM AGAINST 489 ANAEROBES

Agar dilution was used to compare the in vitro activity of CP 99,219 w ith those of ciprofloxacin, grepafloxacin, metronidazole, cefoxitin, p iperacillin, and piperacillin-tazobactam against 489 anaerobes. CP 99, 219 yielded a MIC for 50% of the strains tested (MIC(50)) of 0.25 mu g /ml and a MIC(90) of 1.0 mu g/ml, with 99.6% of the strains susceptibl e at a breakpoint of 2.0 mu g/ml. Ciprofloxacin and grepafloxacin were less active (MIC(50), 4.0 mu g/ml; MIC(90), 32.0 mu g/ml and 2.0 and 16.0 mu g/ml, respectively). Metronidazole was active against all gram -negative rods (MIC(90), 4.0 mu g/ml), but 31% of the gram-positive an aerobes were resistant at >8.0 mu g/ml. Cefoxitin was active against 8 4% of all strains at less than or equal to 16.0 mu g/ml, with a MIC(50 ) of 4.0 mu g/ml and a MIC(90) of 32.0 mu g/ml. Tazobactam enhanced th e activity of piperacillin against >95% of the beta-lactamase-producin g gram-negative anaerobic rods (MIC(90), 16.0 mu g/ml).