In vitro susceptibility of Mycobacterium tuberculosis to ofloxacin and ciprofloxacin in combination with rifampin and isoniazid.

The in vitro susceptibility of Mycobacterium tuberculosis to new quinolones, ofloxacin and ciprofloxacin, alone and in combination with rifampin or isoniazid, was studied by the agar dilution method. At a concentration of 1 mg/l or lower of ofloxacin and ciprofloxacin, 90% of the strains were inhibited. A synergistic effect with rifampin and with isoniazid was demonstrated.