STUDIES ON THE VARIATION OF DEGREES OF RESISTANCE IN ISONIAZID-RESISTANT TUBERCLE BACILLI 1. Variation of INH-resistant Tubercle Bacilli in the Body of Animal. 2. Variation of INH-resistant Tubercle Bacilli by Serial Animal Passage.

Isoniazid resistance in the tubercle bacillus remains a matter of moment to the public health, so research in the behavior of the affected organism concern all who deal with the prevention and care of the still most important communicable disease in Korea. Although many a study disclosed the mystery and potential threat of drug resistance of isoniazid, still conflicting evidence has accumulated in the literature concerning the significance of INH-resistant tubercle bacilli. Several reported studies have shown that isoniazid-resistant mutants of tubercle bacilli may be fully pathogenic for guinea pigs, though these retain all or nearly all of their pathogenicity for white mice(Middiebrook, Morse, 1954). Middlebrook also has shown that isoniazid-resistant mutants of tubercle bacilli recovered in vitro are deficient in endogenous catalase activity and that it is possible to isolate isoniazid-resistant mutants which differ in their magnitude of catalase activity. Therefore there is considerable evidence that tubercle bacilli which are highly resistant to isoniazid have diminution or even virtual loss of pathogenicity for guinea pigs, a property hitherto considered virtually synonymous with pathogenicity for humans(Cohn. Peizer, 1953), Were these highly resistant strains to approve of diminished virulence for humans, it would obviously desirable to attempt to achieve in patients a state of high resistance.