1956 Volume 9 Issue 5 Pages 186-190
The problem of the development of resistance to antituberculous drugs in Mycobacterium tuberculosis is the most important one in the chemotherapy of tuberculosis. Several basic biological considerations on the problem have been made by Yegian and Vanderlinde(1,2), Hsie and Bryson(3) etc. To prevent the development of resistance to streptomycin, the combined effect of PAS with streptomycin has been reported by Graessle and Pietrowski(4) and the effect has been clinically proved by Tempel, et al.(5) The author and his associates also have made several genetic studies(6,7,8,9). These studies have concerned to the frequencies of appearance of mutants in strains already resistant to any antituberculous drug, to the characteristics of drug-resistant strains and to several clinical considerations derived from these in vitro results. Since the combined chemotherapy of tuberculosis has started, several years have already passed through, and now it appears that we face the problem of double or triple resistance in Mycobacterium tuberculosis. The frequency of mutation in mutants resistant to any one drug has been studied by us. However, it seems to be none of the reports concerning with the frequency of mutation to drug resistance in mutants resistant to two antituberculous drugs, that is, so-called double-resistant mutants.
The present paper is concerned with the frequency of mutation to PAS-resistance in a streptomycin- and isoniazid-resistant strain (a strain simultaneously resistant to streptomycin and isoniazid) of M. tuberculosis var. hominis.
