Mycobacterium tuberculosis DNA detection in soluble fraction of urine from pulmonary tuberculosis patients.

ABSTRACT

SETTING: A tertiary care and research institution in Italy. BACKGROUND: Small DNA fragments from cells dying throughout the body have been detected in urine (transrenal DNA [Tr-DNA]). OBJECTIVE: To test the hypothesis that Mycobacterium tuberculosis Tr-DNA could be detected in the urine of pulmonary tuberculosis (TB) patients. DESIGN: We studied 43 patients with culture-confirmed pulmonary TB with no evidence of extra-pulmonary involvement, 10 patients with pulmonary diseases other than TB and 13 healthy controls. DNA was extracted from urine and analysed by semi-nested polymerase chain reaction (PCR). RESULTS: M. tuberculosis-specific sequences were found in the urine of 34 of 43 (79%) TB patients studied, whereas all controls were negative. The transrenal nature of M. tuberculosis DNA was demonstrated by two lines of evidence first, separate analysis of supernatants and sediments from eight of the study patients found seven positive supernatants but only two matched positive sediments. Second, M. tuberculosis-specific sequences were amplified by semi-nested PCR with primers designed for short but not large amplicons. CONCLUSION: Small M. tuberculosis DNA fragments may be detected in the urine of a significant proportion of patients with pulmonary TB. If these observations are confirmed by larger studies, Tr-DNA technology could represent a new approach for detecting pulmonary M. tuberculosis infection.