ABSTRACT
Primary drug resistance to Mycobacterium tuberculosis was investigated from the Division of Tuberculosis, Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University during August 1991 – July 1992. There were 100 isolations of M.tuberculosis, 70 from male patients, the other 30 from female patients. In male patients the largest age groups were 21-30 and 31-40 years. The isolates were 93 percent from sputum, the other 7 percent were from bronchial wash, pus and ascetic fluid. In female patients the largest age group were 11-20 and 21-30 years. The isolates were 83 percent from sputum, the other 17 percent were from brochial wash, pus and pleural fluid. The overall rate of resistance to antituberculosis drugs in this study was 37 percent. The isolates from sputum showed resistance to INH 22 percent and 13 percent, SM 9 percent and 8 percent, EMB 20 percent, RF 9 percent and 8 percent, the isolates from miscellaneous specimen (other than sputum) showed resistance only to INH (20% and 10%). Comparing this result with other reported data revealed that this study showed higher incidence of primary drug resistance to M. tuberculosis.