Effect of Ultraviolet Irradiation on the Acidfastness of Drug Resistant Mutants of Tubercle Bacilli, With Special Reference to the Virulence of Isoniazid Resistant Strains

Abstract

Effect of ultraviolet irradiation on the acidfastness was studied on the drug resistant mutants of tubercle bacilli. Among them, resistant strains to more than 1γ/ml of Isoniazid lost acidfastness, similarly to the avirulent or attenuated ones, by shorter time of UV irradiation than the virulent tubercle bacilli. This phenomenon correlated very well with the pronounced attenuation in virulence to guinea pigs by subcutaneous inoculation. Based on the results, mechanism of Isoniazid resistance was discussed from the standpoint of cell wall structure.