Stool processing methods for Xpert Ultra testing in childhood tuberculosis: A prospective, multi-country accuracy study

Devan Jaganath; Pamela Nabeta; Mark P Nicol; Robert Castro; Peter Wambi; Heather J Zar; Lesley Workman; Rakesh Lodha; Urvashi B Singh; Ashish Bavdekar; Sonali Sanghavi; André Trollip; Aurélien Mace; Maryline Bonnet; Manon Lounnas; Petra de Haas; Edine Tiemersma; David Alland; Padmapriya Banada; Adithya Cattamanchi; Morten Ruhwald; Eric Wobudeya; Claudia M Denkinger; Stool H2H Study Team

doi:10.1093/cid/ciaf289

Stool processing methods for Xpert Ultra testing in childhood tuberculosis: A prospective, multi-country accuracy study

Clin Infect Dis. 2025 Jun 3:ciaf289. doi: 10.1093/cid/ciaf289. Online ahead of print.

Authors

Devan Jaganath^{1

2}, Pamela Nabeta³, Mark P Nicol⁴, Robert Castro^{2

5}, Peter Wambi⁶, Heather J Zar⁷, Lesley Workman⁷, Rakesh Lodha⁸, Urvashi B Singh^{8

9}, Ashish Bavdekar¹⁰, Sonali Sanghavi¹¹, André Trollip³, Aurélien Mace³, Maryline Bonnet¹², Manon Lounnas¹³, Petra de Haas¹⁴, Edine Tiemersma¹⁴, David Alland¹⁵, Padmapriya Banada¹⁵, Adithya Cattamanchi^{2

16}, Morten Ruhwald³, Eric Wobudeya⁶, Claudia M Denkinger^{3

17}; Stool H2H Study Team

Collaborators

Stool H2H Study Team:
Hellen Tukamuhebwa Aanyu, Alfred Andama, Deus Atwiine, Cynthia Baard, Abibatou Diack, Sara Eyangoh, Sylvain Godreuil, Yekiwe Hlombe, Juaneta Luiz, Midori Kato Maeda, Olivier Marcy, Mary G Nabukenya Mudiope, Ezekiel Mupere, Jascent Nakafeero, Gertrude Nanyonga, Moses Nsereko, Ernest A Oumo, Moorine P Sekadde

Affiliations

¹ Division of Pediatric Infectious Diseases, University of California, San Francisco, San Francisco, USA.
² Center for Tuberculosis, University of California, San Francisco, San Francisco, USA.
³ FIND, Geneva, Switzerland.
⁴ Marshall Centre, School of Biomedical Sciences, University of Western Australia, Perth, Australia.
⁵ Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco, USA.
⁶ Walimu, Kampala, Uganda.
⁷ Department of Paedatrics and Child Health, University of Cape Town, Cape Town, South Africa.
⁸ Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India.
⁹ Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India.
¹⁰ Department of Pediatrics, KEM Hospital, Pune, India.
¹¹ Department of Microbiology, KEM Hospital, Pune, India.
¹² TransVIHMH, University of Montpellier, IRD, Inserm, Montpellier, France.
¹³ University of Montpellier, IRD, CNRS, MIVEGEC, Montpellier, France.
¹⁴ KNCV Tuberculosis Foundation, The Hague, The Netherlands.
¹⁵ Public Health Research Institute, Department of Medicine, Rutgers-New Jersey Medical School, Newark, USA.
¹⁶ Division of Pulmonary Diseases and Critical Care Medicine, University of California Irvine, Orange, USA.
¹⁷ Department of Infectious Disease and Tropical Medicine, University Hospital Heidelberg, German Center of Infection Research, partner site Heidelberg, Germany.

PMID: 40460214
DOI: 10.1093/cid/ciaf289

Abstract

Background: Centrifuge-free processing methods support stool Xpert Ultra testing for childhood tuberculosis (TB), but there are limited data on their accuracy, acceptability and usability.

Methods: We conducted a prospective evaluation of stool Xpert Ultra in India, South Africa, and Uganda with three methods: Stool Processing Kit (SPK), Simple One-Step (SOS), and Optimized Sucrose Flotation (OSF). Children <15 years old with presumptive TB had sputum testing with Xpert Ultra and culture. We compared the accuracy of each method to a microbiological reference standard (MRS, TB if Xpert Ultra or culture positive) and a composite reference standard (CRS, TB if Confirmed or Unconfirmed TB). We surveyed laboratory staff to assess acceptability and usability of the methods.

Results: We included 607 children, with a median age of 3.5 years (IQR 1.3-7) and 15.5% HIV positive. Against the MRS, the sensitivities of SPK, SOS and OSF were 36.9% (95% CI 28.6-45.8), 38.6% (95% CI 17.2-51.0), and 31.3% (95% CI 20.2-44.1), respectively. The specificities of SPK, SOS and OSF were 98.2% (95% CI 96.4-99.3), 97.3% (95% CI 93.7-99.1), and 97.1% (95% CI 93.3-99), respectively. The methods were acceptable and usable, but SOS was reported as most feasible to implement in a peripheral facility. Across methods, sensitivity increased among children who were culture-positive (55.0-77.3%) and was low (13-16.7%) against the CRS. Adding stool Xpert Ultra increased sensitivity 0% (OSF) to 11.8% (SPK/SOS) over sputum alone.

Conclusions: Stool processing methods for Xpert Ultra were acceptable, usable, and performed similarly, with highest sensitivity among children with culture-positive TB.

Keywords: Xpert Ultra; centrifuge-free; child; diagnostics; stool; tuberculosis.

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