Objectives: To compare the diagnostic yield of Mycobacterium tuberculosis from induced sputum (IS) and gastric lavage (GL) among children in a community setting.
Methods: Specimen-collection methods for bacteriological confirmation of pulmonary tuberculosis (PTB) were compared during a tuberculosis vaccine trial near Cape Town, South Africa (2001–2006). Children with a tuberculosis contact or compatible symptoms were investigated for suspected PTB. Diagnostic yields from 764 paired IS and GL specimens were compared in 191 culture-confirmed cases.
Measurements and main results: The crude yield of M tuberculosis was 10.4%, n = 108 by IS (5.8%) and n = 127 by GL (6.8%), from a total of 194 cases, of which three had incomplete IS/GL specimen pairs. Agreement between IS and GL was poor (κ = 0.31). The comparative yield of a single IS sample (38%) was equivalent to a single GL sample (42%), with a difference in yield of −4% (95% CI −15% to +7%). The combined yield of same-day IS and GL specimens (67%) was equivalent to two consecutive GL specimens (66%), with a difference in yield of 1% (95% CI −9% to 11%), but significantly greater than two consecutive IS specimens (55%), with a difference in yield of 12% (95% CI 2% to 21%). The adjusted odds of a M tuberculosis culture were increased by a positive tuberculin skin test or chest radiograph compatible with PTB.
Conclusions: In this community setting, the diagnostic yield of a single IS sample was equivalent to that of a single GL sample. The optimal diagnostic yield may be obtained from paired IS and GL specimens taken on a single day or two GL specimens taken on consecutive days.
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Funding: MH, TH, MT, LW, LG, WAH and GH were supported by Aeras Global TB Vaccine Foundation; MH, MT, WAH, and GH are supported by EuropeAID; MH is supported by the NIH (1R01-AI075603-01), as is WAH (R01-AI065653 and N01-AI70022) and GH (D43-TW007115); MH is also supported by Immunopaedia; WAH is also supported by the Dana Foundation, the Bill and Melinda Gates Foundation through Grand Challenges in Global Health Grant Nos 37772 and 37885, and the European and Developing Countries Trials Partnership (EDCTP).
Competing interests: None.
Ethics approval: Obtained.
This work has been presented in part as an oral presentation at the 25th Annual Meeting of the European Society for Paediatric Infectious Diseases, Porto, 2007.