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dc.contributor.authorMtafya, Bariki
dc.contributor.authorSabiiti, Wilber
dc.contributor.authorSabi, Issa
dc.contributor.authorJohn, Joseph
dc.contributor.authorSichone, Emanuel
dc.contributor.authorNtinginya, Nyanda E.
dc.contributor.authorGillespie, Stephen H.
dc.identifier.citationMtafya , B , Sabiiti , W , Sabi , I , John , J , Sichone , E , Ntinginya , N E & Gillespie , S H 2019 , ' Molecular bacterial load assay (MBLA) concurs with culture on the NaOH-induced Mycobacterium tuberculosis loss of viability ' , Journal of Clinical Microbiology , vol. 57 , e01992-18 .
dc.identifier.otherPURE: 258657292
dc.identifier.otherPURE UUID: 7da6c22f-5b79-4a17-a116-e4d25cc3c539
dc.identifier.otherORCID: /0000-0001-6537-7712/work/58531611
dc.identifier.otherORCID: /0000-0002-4742-2791/work/60196329
dc.identifier.otherWOS: 000472800800019
dc.identifier.otherScopus: 85068554734
dc.descriptionThis work was supported by the commonwealth studentship award for Bariki Mtafya at University of St Andrews in UK and European and Developing Countries Clinical Trials Partnership (EDCTP) through TWENDE and PanACEA II grants.en
dc.description.abstractEffective methods to detect viable Mycobacterium tuberculosis (Mtb), the main causative agent of tuberculosis (TB) are urgently needed. To date, cultivation of Mtb is the gold standard which depends on initial sample processing with N-Acetyl-L-Cysteine/Sodium hydroxide (NALC/NaOH), chemicals that compromise Mtb viability and, consequently the performance of downstream tests. We applied culture and the novel Molecular bacterial load assay (MBLA) to measure the loss of Mtb viability following NALC/NaOH treatment of Mtb H37Rv pure culture and clinical sputa from pulmonary TB patients. Compared to untreated controls, NALC/NaOH treatment of Mtb, reduced MBLA detectable bacillary load (estimated colony forming units/milliliter (eCFU/mL) by 0.66±0.21log10- at 23°C (P=0.018) and 0.72±0.08log10- at 30°C (P=0.013). Likewise, NALC/NaOH treatment reduced viable count on solid culture by 0.84±0.02log10- at 23°C (P<0.001) and 0.85±0.01log10- CFU/mL at 30°C (P<0.001) respectively. The reduction in viable count was reflected by a corresponding increase in time to positivity of MGIT liquid culture, 1.2 days at 23°C (P<0.001), and 1.1 days at 30°C (P<0.001). This NaOH-induced Mtb viability loss was replicated in clinical sputum samples, with bacterial load dropping by 0.65±0.17log10 from 5.36±0.24log10- to 4.71±0.16log10- eCFU/mL for untreated and treated sputa respectively. Applying the Bowness et al model, revealed that the treated MGIT time to culture positivity of 142hrs was equivalent to 4.86±0.28log10CFU, consistent with MBLA-measured bacterial load. Our study confirms the contribution of NALC/NaOH treatment to loss of viable bacterial count. Tests that obviate the need of decontamination may offer alternative option for accurate detection of viable Mtb and treatment response monitoring.
dc.relation.ispartofJournal of Clinical Microbiologyen
dc.rights© 2018, American Society for Microbiology. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at
dc.subjectQR Microbiologyen
dc.subjectRA0421 Public health. Hygiene. Preventive Medicineen
dc.titleMolecular bacterial load assay (MBLA) concurs with culture on the NaOH-induced Mycobacterium tuberculosis loss of viabilityen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Medicineen
dc.contributor.institutionUniversity of St Andrews. Infection and Global Health Divisionen
dc.contributor.institutionUniversity of St Andrews. Sir James Mackenzie Institute for Early Diagnosisen
dc.contributor.institutionUniversity of St Andrews. Centre for Biophotonicsen
dc.contributor.institutionUniversity of St Andrews. Global Health Implementation Groupen
dc.contributor.institutionUniversity of St Andrews. Gillespie Groupen
dc.contributor.institutionUniversity of St Andrews. Infection Groupen
dc.contributor.institutionUniversity of St Andrews. Biomedical Sciences Research Complexen
dc.description.statusPeer revieweden

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