Molecular detection of Mycobacterium tuberculosis in poor-quality cough specimens.

Clinical specimens unfit for laboratory processing represent missed opportunities for diagnosing tuberculosis. Poor-quality cough specimens (n=61) from presumptive tuberculosis cases were cultured and GeneXpert MTB/RIF (Xpert) successfully performed on samples transferred by flocked swab into PrimeStore molecular transport medium (PS-MTM). Mycobacterium tuberculosis was grown in culture from 13 (21.3 %) and Xpert reported 15 (24.2 %) positive, of which 10 concordant. RT-PCR of PS-MTM samples showed enhanced sensitivity; three positives were missed by Xpert, five by culture and three more detected for a total of 21 positives (34.4 %).