title: Two groups of Mycobacterium avium complex strains determined according to the susceptibility to rifampicin and ansamycin.
abstract: Mycobacterium avium complex strains previously not exposed to any antituberculosis agents could be divided into two groups according to their susceptibility to rifampicin and ansamycin; one group susceptible to 80 micrograms/ml rifampicin and to 1.25 micrograms/ml ansamycin, and another resistant to these concentrations. In each group, the ratio of the minimal inhibitory concentration of ansamycin against that of rifampicin was greatly different depending on the strain. This naturally occurring resistance to rifampicin and ansamycin was frequently correlated to naturally occurring resistance to ethambutol, kanamycin, enviomycin, kitasamycin, and minocycline, but not correlated to that to isoniazid and sulfadimethoxine. Ansamycin was more active than rifampicin against M. bovis, M. kansasii, M. marinum, M. xenopi, and M. haemophilum.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D047029:Lactams, Macrocyclic; D009162:Mycobacterium avium / Q000145:classification* / Q000187:drug effects; D009163:Mycobacterium bovis / Q000187:drug effects; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D009170:Nontuberculous Mycobacteria / Q000187:drug effects; D012293:Rifampin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D047029:Lactams, Macrocyclic; D012293:Rifampin