Abstract
The in vitro activity of seven quinolone derivatives against 100 clinical isolates of Clostridium difficile was determined. CI934 was the most active, inhibiting 90% of the strains at 4 micrograms/ml and 100% at 8 micrograms/ml. Ofloxacin and ciprofloxacin had moderate activity (16 and 32 micrograms/ml) whereas enoxacin, pefloxacin, norfloxacin, and nalidixic acid had poor activity (128 micrograms/ml).