Field evaluation of a novel preservation medium to transport sputum specimens for molecular detection of Mycobacterium tuberculosis in a rural African setting
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Date
Authors
Omar, Shaheed Vally
Peters, Remco P.H.
Ismail, Nazir Ahmed
Jonkman, Kelly
Dreyer, Andries W.
Said, Halima M.
Ismail, Nabila
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
Molecular tests are revolutionizing diagnosis of tuberculosis (TB). Disease burden is
concentrated in resource-poor countries with inadequate infrastructure and capacity resulting in
delays for specimens to reach the laboratory. We assessed the performance of an innovative
method using a swab to inoculate sputum in a transport medium, PrimeStore® - Molecular
Transport Medium (PS-MTM) for subsequent molecular detection of Mycobacterium
tuberculosis at a centralized facility. A sputum specimen was obtained from suspected TB
patients at rural healthcare facilities in South Africa and a swab taken and placed into PS-MTM
from this specimen, prior to it being processed by either liquid culture or Xpert MTB/Rif assay
(Xpert). A subset from a larger cohort study of a 141 patients was included for analysis, which
included 47 laboratory-confirmed TB patients. M. tuberculosis was detected at 29% by culture,
29% by Xpert and 31% and 36% by real-time PCR of PS-MTM for the culture and Xpert
specimen respectively. Concordance between the method under evaluation with culture was 82%
(McNemar, p=0.55) and 84% (McNemar, p=0.05) for Xpert. Stratified by culture result,
detection rate by real-time PCR of PS-MTM was similar to Xpert for patients with positive
culture (p=0.32), but significantly higher if culture was negative (p=0.008). These results suggest
that swab collection of sputum into PS-MTM provides a promising application for diagnosis of
TB in rural healthcare settings thereby potentially improving the options available for the
diagnosis of TB in countries incapable of applying decentralized high-tech molecular testing.
Description
Keywords
Specimen transport medium sputum, Molecular detection, Mycobacterium tuberculosis, Preservation, Tuberculosis (TB)
Sustainable Development Goals
Citation
Omar, SV, Peters, RPH, Ismail, NA, Jonkman, K, Dreyer, AW, Said, HM, Gwala, T, Ismail, N & Fourie, B 2016, 'Field evaluation of a novel preservation medium to transport sputum specimens for molecular detection of Mycobacterium tuberculosis in a rural African setting', Tropical Medicine & International Health, vol. 21, no. 6, pp. 776-782