Induced sputum or gastric lavage for community-based diagnosis of childhood pulmonary tuberculosis?
OBJECTIVE
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.


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 (kappa = 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.
Hatherill
M
M
South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine (IIDMM), University of Cape Town, Cape Town, South Africa. mark.hatherill@uct.ac.za
Hawkridge
T
T
Zar
H J
HJ
Whitelaw
A
A
Tameris
M
M
Workman
L
L
Geiter
L
L
Hanekom
W A
WA
Hussey
G
G
D001431:Bacteriological Techniques / Q000379:methods; D003153:Community Health Services / Q000379:methods; D005751:Gastric Lavage; D006801:Humans; D007223:Infant; D015999:Multivariate Analysis; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D013048:Specimen Handling / Q000379:methods; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*