In vitro susceptibility of Mycobacterium fortuitum to non-antituberculous antibacterial agents.

A study was made of the in vitro susceptibility of 37 strains of Mycobacterium fortuitum to 14 antimicrobial agents using disc diffusion techniques on Mueller-Hinton agar plates. Nitro-5-hydroxy-8-quinoleine and pipemidic acid inhibited all strains, while furantoin, mandelamine, metronidazole, nalidixic acid, oxolinic acid and trimethoprim proved to be inactive. In addition, various sulphonamides inhibited 59% of the strains tested. Sulphadiazine inhibited 54.1%, sulphafurazole 64.9%, sulphamethizole 64.9%, sulphametoxypyridazine 62.2% and sulphisoxazole 59.5%. Trimethoprim-sulphamethoxazole was effective against 48.6% of the strains due to its sulph component. The sensitivity to sulphonamides varied in accordance with the origin of the strains, those of human origin being generally much more susceptible than those of non-human origin.