Project Details

Stool MTB polymerase chain reaction to improve pediatric TB diagnosis

Alexander Kay, MD

Summary

BACKGROUND: 1) Only 10-20% of children with TB are microbiologically confirmed due to poor performance of existing tests. 2) Pediatric diagnostic specimens, obtained through gastric aspirate, sputum induction or nasopharyngeal aspirate, are often not collected because they are invasive, require additional equipment and perform poorly. GAP: There is a research and data gap on child TB diagnostics using non-respiratory samples, such as stool, to increase test uptake while also maintaining and building on the performance characteristics of traditional samples. HYPOTHESIS: Hypothesis 1: Compared to the reference standard of culture, stool qPCR will have non-inferior sensitivity and specificity vs. Xpert (comparator test) completed on respiratory specimens. Hypothesis 2: Stool Xpert performance will be enhanced by stool homogenization and centrifugation, and the MTBDRplus will identify Mtb and molecular drug resistance in DNA isolated via MPFast soil DNA kits. METHODS: This will be a prospective, cross-sectional, case control study, stool diagnostics will be assessed compared to the traditional diagnostic pathway. Children (age 6 months- 18 years) who are being evaluated for TB will have stool collected in addition to standard diagnostic tests. RESULTS: Stool processing methods did not significantly impact the performance of stool Xpert Ultra in a direct laboratory comparison. Systematic review evidence from multiple studies indicates that Xpert Ultra testing on stool has a high degree of diagnostic accuracy and stool is now recommended by the World Health Organization as an acceptable diagnostic specimen for TB. Drug susceptibility testing from TB detected in stool has previously been limited; however, TB DNA isolation techniques optimized for stool in this study can support comprehensive drug resistance detection using targeted next generation sequencing. IMPACT: A test that performs similarly to current diagnostics but is used more frequently because it is non-invasive and requires no training for sample collection could increase the microbiologic diagnosis of pediatric

Publications:

Sibandze DB, Kay A, Dreyer V, Sikhondze W, Dlamini Q, DiNardo A, Mtetwa G, Lukhele B, Vambe D, Lange C, Glenn Dlamini M, Ness T, Mejia R, Kalsdorf B, Heyckendorf J, Kuhns M, Maurer FP, Dlamini S, Maphalala G, Niemann S, Mandalakas A. Rapid molecular diagnostics of tuberculosis resistance by targeted stool sequencing. Genome Med. 2022 May 19;14(1):52. doi: 10.1186/s13073-022-01054-6. PMID: 35585607; PMCID: PMC9118838.

Kay AW, González Fernández L, Takwoingi Y, Eisenhut M, Detjen AK, Steingart KR, Mandalakas AM. Xpert MTB/RIF and Xpert MTB/RIF Ultra assays for active tuberculosis and rifampicin resistance in children. Cochrane Database Syst Rev. 2020 Aug 27;8(8):CD013359. doi: 10.1002/14651858.CD013359.pub2. PMID: 32853411; PMCID: PMC8078611.

Jasumback CL, Dlamini Q, Kahari J, Maphalala G, Dlamini MG, Dube GS, DiNardo A, Kirchner HL, Mandalakas A, Kay AW. Laboratory comparison of stool processing methods for Xpert® Ultra. Public Health Action. 2021 Jun 21;11(2):55-57. doi: 10.5588/pha.20.0079. PMID: 34159062; PMCID: PMC8202631.

Brunetti, Marie, Sathyanath Rajasekharan, Piluca Ustero, Katherine Ngo, Welile Sikhondze, Buli Mzileni, Anna Mandalakas, and Alexander W. Kay. "Leveraging tuberculosis case relative locations to enhance case detection and linkage to care in Swaziland." Global health research and policy 3, no. 1 (2018): 3.

DiNardo, Andrew R., Alexander W. Kay, Gugu Maphalala, Nadine M. Harris, Celia Fung, Godwin Mtetwa, Pilar Ustero et al. "Diagnostic and Treatment Monitoring Potential of A Stool-Based Quantitative Polymerase Chain Reaction Assay for Pulmonary Tuberculosis." The American journal of tropical medicine and hygiene (2018).

Kay, Alexander W., Shamim M. Islam, Kristen Wendorf, Janice Westenhouse, and Pennan M. Barry. "Interferon-γ Release Assay Performance for Tuberculosis in Childhood." Pediatrics 141, no. 6 (2018): e20173918.

DiNardo, Andrew R., Tomoki Nishiguchi, Emily M. Mace, Kimal Rajapakshe, Godwin Mtetwa, Alexander Kay, Gugu Maphalala et al. "Schistosomiasis Induces Persistent DNA Methylation and Tuberculosis-Specific Immune Changes." The Journal of Immunology (2018): ji1800101.

Sekadde, Moorine Penninah, and Alexander W. Kay. "Tuberculosis Prevention: an Under Prioritized yet Critical Intervention to Reduce Child Tuberculosis Morbidity and Mortality." Current Tropical Medicine Reports 5, no. 1 (2018): 51-58.

Kay A, Garcia-Prats AJ, Mandalakas AM. HIV-associated pediatric tuberculosis: prevention, diagnosis and treatment. Curr Opin HIV AIDS. 2018 Nov;13(6):501-506. doi: 10.1097/COH.0000000000000500. PMID: 30286040.