{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T09:18:10Z","timestamp":1781083090828,"version":"3.54.1"},"posted":{"date-parts":[[2026,4,3]]},"group-title":"Respiratory Medicine","reference-count":25,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T00:00:00Z","timestamp":1775174400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,4,3]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                <jats:sec>\n                  <jats:title>Rationale<\/jats:title>\n                  <jats:p>Sputum-based testing using Xpert MTB\/RIF Ultra (Xpert) is the most common molecular testing method for diagnosing tuberculosis (TB).<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Objectives<\/jats:title>\n                  <jats:p>To evaluate whether sputum quality influences Xpert positivity and diagnostic accuracy.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>We screened consecutive people for presumptive TB in India, the Philippines, Vietnam, Nigeria, South Africa, Uganda, and Zambia as part of the R2D2 TB Network and ADAPT studies. Participants provided 2-3 sputum samples for Xpert and culture reference testing. The quality of the first sputum sample was graded following standardized procedures by trained research staff and used for Xpert testing. We performed logistic regression to evaluate whether sputum grade was independently associated with Xpert positivity, and calculated sensitivity and specificity of Xpert against a culture-based microbiological reference standard (MRS).<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Measurements and Main Results<\/jats:title>\n                  <jats:p>Among 1,855 participants, 798 (43%) were female, 348 (19%) were living with HIV (PLHIV), and 1795 (97%) had a cough of \u22652 weeks. Overall, 313 (17%) had a positive Xpert result. Most sputum samples were salivary (83%). Xpert positivity was lowest among salivary samples (16.1%) and highest among purulent samples (31.2%). After adjusting for demographic and clinical variables, there was no significant association between any sputum grade and Xpert positivity. Xpert sensitivity (salivary: 89%, mucoid: 91%, mucopurulent: 87%, purulent: 100%) and specificity (&gt;98%) were high across sputum grades.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>Sputum quality was not independently associated with Xpert positivity and Xpert sensitivity was high across all sputum grades. These findings support molecular testing of all sputum samples for TB diagnosis regardless of macroscopic appearance.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>Scientific Knowledge on the Subject<\/jats:title>\n                  <jats:p>Xpert MTB\/RIF Ultra (Xpert Ultra) is a WHO-recommended initial diagnostic test for pulmonary tuberculosis. Historical laboratory practice, derived from the smear microscopy era, has emphasized sputum macroscopic quality, with many programs recommending rejection of salivary sputum as inadequate. Prior studies evaluating sputum quality and Xpert performance yielded mixed results, and were limited by small sample sizes, single-country designs, heterogeneous sputum grading systems, and predominant use of the first-generation Xpert MTB\/RIF assay.<\/jats:p>\n                <\/jats:sec>\n                <jats:sec>\n                  <jats:title>What This Study Adds to the Field<\/jats:title>\n                  <jats:p>In this large and geographically diverse evaluation of 1,855 participants across seven high-burden countries, macroscopic sputum quality was not independently associated with Xpert Ultra positivity or diagnostic accuracy. Xpert Ultra demonstrated high sensitivity and specificity across all sputum grades, including salivary specimens, which comprised over 80% of samples. These findings, generated by using a standardized sputum grading protocol and a culture-based microbiological reference standard, provide robust evidence that sputum quality-based rejection criteria are unnecessary for Xpert Ultra testing. Revising laboratory guidelines to accept all expectorated sputum regardless of appearance could improve case detection and reduce diagnostic delays in high-burden settings.<\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.04.01.26350003","type":"posted-content","created":{"date-parts":[[2026,4,4]],"date-time":"2026-04-04T00:00:14Z","timestamp":1775260814000},"source":"Crossref","is-referenced-by-count":1,"title":["Impact of sputum quality on Xpert MTB\/RIF Ultra test results for tuberculosis: A multi-country study"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9318-2514","authenticated-orcid":false,"given":"Caitlin A.","family":"Moe","sequence":"first","affiliation":[{"name":"Division of Pulmonary Diseases and Critical Care Medicine, University of California Irvine, Orange, USA"},{"name":"Center for Tuberculosis, University of California San Francisco, San Francisco, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sraoshi","family":"Barua","sequence":"additional","affiliation":[{"name":"Joe C. Wen School of Population & Public Health, University of California Irvine, Orange, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shrivaas","family":"Vijayan","sequence":"additional","affiliation":[{"name":"University of California Davis, Davis, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0526-0007","authenticated-orcid":false,"given":"Alfred O.","family":"Andama","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Makerere University College of Health Sciences, Kampala, Uganda"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7847-4271","authenticated-orcid":false,"given":"John","family":"Bimba","sequence":"additional","affiliation":[{"name":"Zankli Research Center, Bingham University, Karu, Nigeria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9405-8494","authenticated-orcid":false,"given":"Devasahayam J","family":"Christopher","sequence":"additional","affiliation":[{"name":"Christian Medical College, Vellore, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Van Luong","family":"Dinh","sequence":"additional","affiliation":[{"name":"Vietnam National Lung Hospital, Hanoi, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4510-0473","authenticated-orcid":false,"given":"Ha","family":"Phan","sequence":"additional","affiliation":[{"name":"Centre for the Promotion of Advancement of Society, Hanoi, Vietnam"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9216-2415","authenticated-orcid":false,"given":"Grant","family":"Theron","sequence":"additional","affiliation":[{"name":"DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William","family":"Worodria","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Makerere University College of Health Sciences, Kampala, Uganda"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Charles","family":"Yu","sequence":"additional","affiliation":[{"name":"De La Salle Medical and Health Sciences Institute, Cavite, Philippines"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-1729-5463","authenticated-orcid":false,"given":"Kristin","family":"Kremer","sequence":"additional","affiliation":[{"name":"Division of Tuberculosis Elimination & Health Systems Innovations, KNCV Tuberculosis Foundation, the Hague, the Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2811-1311","authenticated-orcid":false,"given":"Payam","family":"Nahid","sequence":"additional","affiliation":[{"name":"Center for Tuberculosis, University of California San Francisco, San Francisco, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Seda","family":"Yerlikaya","sequence":"additional","affiliation":[{"name":"Heidelberg University Medical Faculty, Heidelberg University Hospital, Department of Infectious Disease, Heidelberg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7216-7067","authenticated-orcid":false,"given":"Claudia M.","family":"Denkinger","sequence":"additional","affiliation":[{"name":"Heidelberg University Medical Faculty, Heidelberg University Hospital, Department of Infectious Disease, Heidelberg, Germany"},{"name":"German Centre for Infection Research (DZIF), partner site Heidelberg University Hospital, Heidelberg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6553-2601","authenticated-orcid":false,"given":"Adithya","family":"Cattamanchi","sequence":"additional","affiliation":[{"name":"Division of Pulmonary Diseases and Critical Care Medicine, University of California Irvine, Orange, USA"},{"name":"Center for Tuberculosis, University of California San Francisco, San Francisco, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3609-5403","authenticated-orcid":false,"given":"Monde","family":"Muyoyeta","sequence":"additional","affiliation":[{"name":"Centre for Infectious Disease Research in Zambia, Lusaka"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026040700200602000_2026.04.01.26350003v1.1","unstructured":"World Health Organization. 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