Ofloxacin: antibacterial activity, induction of resistance and killing curves

The antibacterial activity of ofloxacin was compared to that of nalidixic acid, norfloxacin and against various strains. This new quinolone was about 100 times more active than nalidixic acid, and pipemidic acid and generally 2 to 4 fold more active than norfloxacin and pefloxacin except against Pseudomonas aeruginosa. The increase of resistance to ofloxacin, norfloxacin and pefloxacin seems to plateau, usually at about 16 times the initial MIC. The bactericidal activity of ofloxacin also appeared quickly and more rapidly than that of norfloxacin.