[In vitro study of the susceptibility of mycobacteria to sulfonamides by the disc and percentage methods (author's transl)].

Disc method is used as a preliminary qualitative test, in order to check the mycobacterial susceptibility to sulfadiazine and cotrimoxazole, while the percentage method gives a quantitative antibiogram in testing with precision the microbial susceptibility to sulfadiazine, sulfamethoxazole, sulfamethoxydiazine, sulfadimethoxine and cotrimoxazole. Both methods are performed in tube, on Löwenstein-Jensen medium. The mycobacteria tested include 114 strains representing 10 species. The results show that sulfonamides and cotrimoxazole exert an inhibitory power which can vary according to the species : it is excellent for M. fortuitum, M. kansasii, M. marinum, M. scrofulaceum, M. szulgai and M. xenopi, weaker for M. ulcerans, mediocre for M. avium and M. tuberculosis, non existent for M. bovis. The percentage method shows that the MIC is less with cotrimoxazole and sulfamethoxazole than with other sulfonamides. Within the same species as M. avium, there are marked differences of bacterial susceptibility to these antibacillaries, according to the strains.