Molecular detection of Mycobacterium tuberculosis from sputum transported in PrimeStore(®) from rural settings

Abstract

SETTING : Mopani District, South Africa. OBJECTIVE : To explore remote, molecular detection of Mycobacterium tuberculosis from sputum transported using PrimeStorew Molecular Transport Medium (PSMTM) compared to settings where microscopy or Xpertw MTB/RIF is used as the baseline test. DESIGN : Two sputum specimens were collected from patients with cough of72 weeks at clinics in rural South Africa. Shortly after expectoration and before processing using Xpert, microscopy and liquid culture, a flocked swab was swirled in each of these specimens and placed in PS-MTM. Swabs were stored and transported to the United States at ambient temperature for real-time PrimeMixw polymerase chain reaction (PM-PCR). RESULTS : Of 132 patients, 23 (17%) were positive on microscopy, 39 (30%) on Xpert and 44 (33%) by PSMTM/PSMTM/ PM-PCR. Concordance of PS-MTM/PM-PCR with positive microscopy and Xpert was respectively 96% and 85%. Of 107 microscopy-negative samples, 22 (21%) were positive using PS-MTM/PM-PCR, while 11/91 (12%) Xpert-negative samples were PS-MTM/ PM-PCR-positive. PS-MTM/PM-PCR positivity was significantly higher than smear microscopy positivity (P , 0.001), but similar to Xpert (P ¼ 0.33). CONCLUSION: PCR testing of specimens transported in PS-MTM would enhance TB diagnosis in settings where smear microscopy is the baseline diagnostic test, and could provide an alternative in settings where Xpert testing is not available.