In vitro activity of four fluoroquinolones against eighty-six isolates of mycobacteria.

The in vitro activity of pefloxacin, norfloxacin, ofloxacin and ciprofloxacin against 86 strains of mycobacteria was evaluated by broth dilution. While Mycobacterium avium, Mycobacterium scrofulaceum and Mycobacterium chelonae were resistant to all four antibacterials, the susceptibility of the other species, Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium xenopi and Mycobacterium fortuitum, depended on the antibiotic. Ofloxacin and ciprofloxacin (MIC90: 0.5 - 2 mg/l) were more active than pefloxacin and norfloxacin (MIC90: 2 - 16 mg/l).