2002 Volume 77 Issue 7 Pages 533-535
In the antimycobacterial susceptibility test for INH using the egg-based Ogawa media, 3 concentrations (0.1, 1, or 5μg/ml) of INH were used, and 1μg/ml was used as a critical concentration for INH resistance. However, it was controversial whether INH 0.1μg/ml resistant M.tuberculosis was clinically significant or not. We investigated the MIC values of INH 0.1μg/ml resistant strains by using BrothMIC MTB-1 method, and 115 strains of M.tuberculosis confirmed by DNA-prove test were used. The distribution of MIC values of 115 strains determined by Ogawa INH susceptibility test was shown in figure. By BrothMIC MTB-1 method, they were classified into 3 groups; susceptible, low resistant and high resistant groups. The mean MIC value of INH 0.1μg/ml resistant M.tuberculosis was estimated to be 4.53μg/ml with its 95 % confidence interval 3.21-5.85μg/ml, and they were determined as “resistant” in BrothMIC MTB-1 method.
These results supported the idea that patients with INH 0.1μg/ml resistant M.tuberculosis strains should be regarded as clinically “resistant”.
