In-vitro activity of ciprofloxacin against clinical isolates of mycobacteria resistant to antimycobacterial drugs.

The activity of ciprofloxacin against 42 clinical isolates of mycobacteria was studied in vitro by the 1% standard proportion method on Lowenstein-Jensen medium. Ciprofloxacin was found active against all strains of Mycobacterium tuberculosis sensitive to streptomycin, isoniazid, ethambutol and rifampicin. The MIC of ciprofloxacin was 3.2 mg/l. This concentration of ciprofloxacin was sufficient to inhibit almost all strains showing intermediate sensitivity or resistance to one or more of the above agents. The same phenomenon was also observed with the atypical isolates.