Field evaluation of a novel preservation medium to transport sputum specimens for molecular detection of Mycobacterium tuberculosis in a rural African setting.
To assess the performance of an innovative method of transporting sputum to centralised facilities for molecular detection of Mycobacterium tuberculosis: using a swab to inoculate sputum in a transport medium, PrimeStore(®) Molecular Transport Medium (PS-MTM).



Two sputum specimens were obtained from suspected patients with tuberculosis (TB) at rural healthcare facilities in South Africa. A swab was taken from each specimen and placed into PS-MTM, prior to it being processed by either liquid culture or Xpert MTB/RIF assay (Xpert).



A total of 141 patients (including 47 with laboratory-confirmed TB) were included in this analysis. M. tuberculosis was detected at 29% by culture and 29% by Xpert, whereas 31% tested positive by IS6110 real-time PCR of PS-MTM from the culture and 36% from the Xpert-paired specimen. 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, the detection rate by IS6110 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 for transport is a promising method for diagnosis of TB in rural healthcare settings, thereby potentially improving the options available for molecular diagnosis of TB in countries incapable of applying decentralised high-tech molecular testing.
Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.|Centre for Tuberculosis, National TB Reference Laboratory, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa.
Shaheed V
SV
Omar
Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.|Anova Health Institute, Johannesburg, South Africa.
Remco P H
RP
Peters
Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.|Centre for Tuberculosis, National TB Reference Laboratory, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa.
Nazir A
NA
Ismail
Anova Health Institute, Johannesburg, South Africa.
Kelly
K
Jonkman
Centre for Tuberculosis, National TB Reference Laboratory, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa.
Andries W
AW
Dreyer
Centre for Tuberculosis, National TB Reference Laboratory, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa.
Halima M
HM
Said
Centre for Tuberculosis, National TB Reference Laboratory, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa.
Thabisile
T
Gwala
Centre for Tuberculosis, National TB Reference Laboratory, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa.
Nabila
N
Ismail
Department of Medical Microbiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.
P Bernard
PB
Fourie
D000328:Adult; D003470:Culture Media; D005260:Female; D006801:Humans; D008297:Male; D009169:Mycobacterium tuberculosis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012293:Rifampin; D012424:Rural Population; D013019:South Africa; D013048:Specimen Handling / Q000379:methods*; D013183:Sputum / Q000382:microbiology*; D014186:Transportation; D014397:Tuberculosis, Pulmonary / Q000382:microbiology*
D003470:Culture Media; D012293:Rifampin
Conservation; Mycobacterium tuberculosis; detección molecular; détection moléculaire; esputo; expectoration; medio de transporte de muestras; milieu de transport d’échantillon; molecular detection; preservación de Mycobacterium tuberculosis; preservation; specimen transport medium; sputum