Follow-up of tuberculosis patients undergoing standard anti-tuberculosis chemotherapy by using a polymerase chain reaction.

We have analysed the clearance of Mycobacterium tuberculosis in sputum specimens from pulmonary tuberculosis patients undergoing 6-month chemotherapy, using the polymerase chain reaction (PCR) and standard microbiological methods. In a group of 19 patients, 11 (58%) were smear- or culture-positive and 13 (74%) were PCR-positive before treatment. Of the 16 patients followed from 2 months after the start of treatment and thereafter, all became smear-negative and culture-negative, whereas, with PCR, 4 (27%), 2 (13%) and 1 (7%) of these patients remained positive after 2, 3 and 6 months, respectively. These results suggest the possible usefulness of PCR in monitoring the efficacy of treatment when bacteriological tests are negative, so as to identify patients with a high risk of relapse.