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

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.