In-vitro activity of six fluorinated quinolones against Mycobacterium tuberculosis

Thirty-five clinical isolates of Mycobacterium tuberculosis, 24 susceptible and 11 resistant to conventional primary antituberculous drugs, were tested against six new quinolones. The mode MICs of isoniazid susceptible organisms on 7H11 agar for ciprofloxacin, ofloxacin, enoxacin, norfloxacin, CI-934 and A56620 were 1.0, 1.0, 2.0, 2.0, 1.0 and 1.0 mg/l, respectively. Strains resistant to isoniazid and other antituberculous agents were usually inhibited within one dilution of these values. These new quinolones could serve as alternate therapeutic agents or they may accelerate the antimycobacterial effects of conventional chemotherapy; these hypotheses should now be tested in experimental infections.