[A supplement study on the in vitro activity of sulfadimethoxine on Mycobacterium avium complex--combined effect with other antituberculosis drugs].
Previously the author observed that sulfadimethoxine is most effective among sulfa drugs against Mycobacterium avium complex strains (Tsukamura, M.: Kekkaku 58: 247-250, 1983) and used this drug in the treatment of pulmonary infection caused by M. avium complex (Tsukamura, M.: Kekkaku 59: 33-37, 1983). In the present study, some supplemental observations were carried out on the in vitro activity of this drug. In vitro susceptibility testing of sulfadimethoxine by the use of Ogawa egg medium was influenced by the number of viable bacteria (colony-forming units) used in the susceptibility testing. By the use of small inocula (50 to 100 colony-forming units), minimal inhibitory concentration (MIC) was determined as 0.8 to 3.13 micrograms/ml, whereas, by the use of large inocula, the MIC was determined as 6.25 to 25 micrograms/ml. Furthermore, the prolongation of incubation time resulted in the elevation of the MIC. The finding shows that the activity of this drug is only to delay the growth. Comparing various combinations with low concentrations of other drugs, combinations with p-aminosalicylate, isoniazid and pyrazinamide seemed to be antagonistic, and combinations with the other drugs seemed to be additive. The influence of the inoculation size on the reading of MICs were compared in Mycobacterium tuberculosis and M. avium complex strains. The susceptibility testings to most drugs were influenced by the inoculation size. However, the testings to ethionamide, ethambutol and isoniazid in M. tuberculosis strains were less influenced by the inoculation size. In contrast, the susceptibility testings to ethionamide and isoniazid in M. avium complex strains seemed to be more influenced.(ABSTRACT TRUNCATED AT 250 WORDS)
Tsukamura
M
M
D000995:Antitubercular Agents / Q000494:pharmacology; D004347:Drug Interactions; D008826:Microbial Sensitivity Tests; D015269:Mycobacterium avium Complex / Q000187:drug effects* / Q000254:growth & development; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D013412:Sulfadimethoxine / Q000008:administration & dosage / Q000494:pharmacology*
D000995:Antitubercular Agents; D013412:Sulfadimethoxine