Objectives: To compare diagnostic yield of Mycobacterium tuberculosis from induced sputum (IS) and gastric lavage (GL) among children in a community setting.
Methods: Specimen collection methods for bacteriologic 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 (95% confidence intervals, CI) 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%), in a total of 194 cases, of which 3 had incomplete IS/GL specimen pairs. Agreement between IS and GL was poor (kappa = 0.31). Comparative yield of a single IS (38%) was equivalent to a single GL (42%), with difference in yield of - 4% (CI -15 to +7%). Combined yield of same-day IS and GL (67%) was equivalent to two consecutive GL (66%), with difference in yield of 1% (-9 to 11%), but significantly greater than two consecutive IS (55%), difference in yield 12% (CI 2 to 21%). Adjusted odds of M. tuberculosis culture were increased by positive tuberculin skin test or chest radiograph.
Conclusions: In this community setting, diagnostic yield of a single IS was equivalent to a single GL. Optimal diagnostic yield may be obtained from paired IS and GL on a single day, or two GL on consecutive days.