Polymerase chain reaction for assessing treatment response in patients with pulmonary tuberculosis

The use of the polymerase chain reaction (PCR) for assessing treatment response in tuberculosis was investigated. Serial sputum samples were analyzed from 10 Tanzanian patients treated for smear-positive pulmonary tuberculosis, including 4 who relapsed after initially successful treatment. A one-tube nested PCR with a colorimetric detection system was compared with microscopy and culture. Samples were found to be negative by microscopy before they were by PCR or culture, often remaining positive 1-2 months longer by PCR than by culture. For the 76 samples available for both culture and PCR, there was a 76% (58/76) agreement between the methods. Nine samples were negative by culture but positive by PCR; 7 were either negative (5) or equivocal (2) by PCR despite being positive by culture. Two of the 4 relapse cases were detected earlier by PCR than by culture. These results demonstrate that PCR is a promising method for assessing treatment response in pulmonary tuberculosis.