Comparison of activities of trovafloxacin (CP-99,219) and five other agents against 585 anaerobes with use of three media

Agar dilution testing was used to compare the in vitro activities of trovafloxacin and ofloxacin, ciprofloxacin, imipenem, metronidazole, and clindamycin against 585 anaerobes. The activity of trovafloxacin was superior to those of ofloxacin and ciprofloxacin, with 94%, 91%, 96%, 100%, 90%, and 100% inhibition of Bacteroides fragilis, non-fragilis Bacteroides species, Peptostreptococcus magnus/Peptostreptococcus micros, Clostridium perfringens, Prevotella bivia/Prevotella disiens, and Fusobacterium species, respectively, at a breakpoint of 2 mu g/mL. Trovafloxacin was more active than clindamycin against most anaerobes and slightly less active than imipenem and metronidazole. Different testing media, which were compared side by side, did affect the in vitro activities of trovafloxacin, ofloxacin, and ciprofloxacin but did not affect those of the other antibiotics. Testing with supplemented brain-heart infusion agar demonstrated fewer minimum inhibitory concentrations than did testing with Wilkins-Chalgren agar and supplemented brucella agar. The activity of trovafloxacin was twofold lower when the pH of the testing media was adjusted to 6.0 than when the pH of the testing media was adjusted to 7.0 or 7.5.