Culture examination of sputum is known to be the best tool for assessing the prognosis of pulmonary tuberculosis patients. Controlled clinical trials with Short Course Chemotherapy (SCC) have shown that culture examination of sputum at the end of two months elicited a high degree of conversion, while smear results were inferior due to presence of dead organisms in the sputum. But, it is not possible to provide sputum culture facilities in the District TB Programme (DTP). Since smear examination facilities is widely available under the DTP, this paper examines the comparability of smear results with culture in patients treated with SCC. It also examines the value if any, of an early evaluation of the treatment outcome with SCC under operational conditions by doing smear examination at two months. Data from two operational studies on SCC are utilised for this purpose.

Of 256 total patients examined, 62 were smear positive at the end of two months, but 41 of them were excreting non- viable bacilli and were culture negative. Nevertheless, in predicting the final outcome of chemotherapy, no significant difference was observed between smear and culture examination at the end of two months. Smear positivity at the end of 2 months, by itself, cannot be considered to bode an unfavourable response, whereas negativity had a good probability of a favourable response. Microscopy in SCC gave as reliable a result as culture both during and at the end of chemotherapy. Hence, a properly conducted smear examination is as good as culture for diagnostic and prognostic purposes under operational conditions.