Use of string test and stool specimens to diagnose pulmonary tuberculosis.

Background: The Xpert MTB/RIF (MTB/RIF) test has advanced the field of tuberculosis (TB) diagnostics; however, depending on age and HIV status, 10-85% of individuals with presumed pulmonary TB (PTB) are unable to produce sputum.

Methods: The feasibility of using MTB/RIF and culture on stool and string test specimens from 13 adult patients with presumed PTB was studied.

Results: The string test was well tolerated with a median Wong Baker Faces score of 2. The string test had 100% sensitivity and specificity by MTB/RIF and 87.5% sensitivity and 100% specificity by culture. In stool, Mycobacterium tuberculosis DNA was detected in all cases of culture-confirmed PTB.

Conclusion: The string test and stool provide diagnostic specimens that warrant further investigation.