"Assessment of the sensitivity and specificity of Xpert MTB/RIF assay . . . "

"Assessment of the sensitivity and specificity of Xpert MTB/RIF assay as an early sputum biomarker of response to tuberculosis treatment"
Lancet Jul 1
http://www.lancet.com/journals/lanres/article/PIIS2213-2600(13)70119-X/fulltext
"Interpretation

The poor specificity precludes the use of the Xpert MTB/RIF assay as a biomarker for monitoring tuberculosis treatment, and should not replace standard smear microscopy and culture."