[Bactericidal activity of ofloxacin against Mycobacterium kansasii]

Bactericidal activity of ofloxacin against Mycobacterium kansasii was observed in in-vitro experiment. Tested bacteria were suspended to a concentration of one mg wet weight per ml in 10 ml of Dubos liquid medium containing no drug or containing 1 or 3 micrograms/ml ofloxacin and incubated at 37 degrees C. The number of colony-forming units contained in a 0.02 ml-sample of the Dubos liquid medium was counted after incubation for 0, 1, 3 and 7 days. The number of colonies was counted in Ogawa egg medium, to which was inoculated a 0.02 ml-sample of dilutions of the medium by a spiral loop that can deliver a 0.02 ml-sample by one inoculation. The bactericidal activity of ofloxacin against M. kansasii appeared after incubation of 3 days or later. This characteristic was different from the bactericidal activity against Mycobacterium tuberculosis, which appeared after incubation of 24 hours.