Tuberc Respir Dis.  1970 Mar;17(1):43-51. 10.4046/trd.1970.17.1.43.

A Study on Sensitivity to Thiacetazone of Tubercle Bacilli Isolated from Patients in Korea

• KMID: 2529135
• DOI: http://doi.org/10.4046/trd.1970.17.1.43

Abstract

A regimen of thiacetazone plus isoniazid has been administrated as one of the standard regimens in the treatment of 15,000 Korean patients with pulmonary tuberculosis through every health center all over the country. Apart from the risk of toxicity, a further reason for caution before using thiacetazone out side of Africa is the possibility that tubercle bacilli from different countries may vary in their sensitivity to the drug. This possibility was first raised when Thomas and others (1961) reported that untreated South lndian patients were more resistant to thiacetazone than British patients. A comparison was therefore undertaken and is reported here:
Materials and methods
Sensitivity tests to thiacetazone were done on cultures of tubercle bacilli isolated from 176 Korean, 31 British and 20 Hong Kong patients without previous antituberculosis chemotherapy and with INH, PAS and SM sensitive organisms. The British and Hong Kong strains were sent by Prof. D. A. Mitchison from the Medical Research Council’ s Unit for Research of Drug Sensitivity in London. The tests were done two ways, the standard MIC and the dilute inoculum MIC by the British Medical Research Council' s technique. The results were read as a MIC (minimal inhibitory concentration). 1) The sensitivity to thiacetazone of the standard strain H₃₇Rv was the MIC of 1 mcg. / ml; on the other hand the MIC of 1 mcg. / ml. or more with 50.1 % of the Korean, 22.6% of the British, and 70.0% of the Hong Kong cultures, respectively. 2) The dilute inoculum MIC of 1 mcg. / ml. or more was 32.0% of the Korean, 12.9% of the British, and 55.0% of the Hong Kong cultures and statistically significant (P. ranging from 0.0275 to 0.005) , respectively. 3) A comparison of geographical distribution of natural thiacetazone sensitivity of the dilute inoculum MIC 1 mcg./ml. or more was 30. 0% of the Seoul-Kyunggi patients, 26.9% of the Honam patients, and 38.7% of the Kyungnam patients; with the geometric means of the mean inhibitory concentrations being 0.55 mcg. 1ml. , and 0.56 mcg. / ml. 0.56 mcg. / ml. respectively. This was not statistical1y significant (P> 0.05). 4) A comparison between the standard MIC with the dilute inoculum MIC technique was undertaken; the results showed the standard MIC technique was higher incidence of resistance than dilute inoculum MIC technique.