Detection of Apparent Cell-free M. tuberculosis DNA from Plasma

New diagnostics are needed to improve clinicians' ability to detect tuberculosis (TB) disease in key populations such as children and persons living with HIV and to rapidly detect drug resistance. Circulating cell-free DNA (ccfDNA) in plasma is a diagnostic target in new obstetric and oncologic applications, but its utility for diagnosing TB is not known. Here we show that Mycobacterium tuberculosis complex DNA can be detected in plasma of persons with sputum smear-positive TB, even in the absence of mycobacteremia. Among 40 participants with bacteriologically-confirmed smear-positive TB disease who had plasma tested by quantitative PCR (qPCR), 18/40 (45%) had a positive result on at least one triplicate reaction. Our results suggest that plasma DNA may be a useful target for improving clinicians' ability to diagnose TB. We anticipate these findings to be the starting point for optimized methods of TB ccfDNA testing and sequence-based diagnostic applications such as molecular detection of drug resistance.