Comparative in vitro activities of ciprofloxacin and other 4-quinolones against Mycobacterium tuberculosis and Mycobacterium intracellulare

The in vitro activity of ciprofloxacin, ofloxacin, amifloxacin, and norfloxacin against 22 clinical isolates of Mycobacterium tuberculosis was evaluated by agar dilution. The MICs for 90% of the isolates of ciprofloxacin and ofloxacin were 0.5 and 1 microgram/ml, respectively. Amifloxacin and norfloxacin were less active. The MICs for 90% of the isolates of ciprofloxacin and ofloxacin against 20 clinical isolates of Mycobacterium intracellulare were determined by agar dilution to be 2 and 8 micrograms/ml, respectively.