• A C C Carvalho, R F Schumacher, S Bigoni, E Soncini, L Notarangelo, A Apostoli, C Bonfanti, D Cirillo, P Mantegani, F Porta, M Comelli, and A Matteelli.
• Institute of Infectious and Tropical Diseases, University of Brescia, Spedali Civili di Brescia, Piazza Spedali Civili di Brescia 1, 25125, Brescia, Italy. a.carvalho@libero.it
• Infection. 2013 Aug 1; 41 (4): 827-31.

BackgroundInterferon-gamma release assays (IGRAs) have high specificity and sensitivity for the diagnosis of tuberculosis (TB) infection. However, their role as a screening tool in children with immunodeficiency disorders is still unclear. In the present study, we performed a contact investigation using serial IGRAs on children with immunodeficiency conditions exposed to a contagious TB patient.MethodsChildren who were exposed to a contagious TB case underwent serial QuantiFERON(®) TB Gold In-Tube (QFT-GIT) and T-SPOT(®).TB (T-SPOT) testing.ResultsEighteen children were tested. At the first testing, only two children (11 %) were positive to T-SPOT. Indeterminate results were more frequent with QFT-GIT (35 %) than with T-SPOT (12 %). In the multivariable analysis, a statistically significant association of lymphocyte count <500 cells/mm(3) (p < 0.00005) and low age (p = 0.03) with indeterminate results for the QFT-GIT test but not for T-SPOT (p = 0.10 and p = 0.88, respectively) was found. At the end of October 2012, 15 of the 18 children were alive and none developed active TB disease.ConclusionT-SPOT provided more determinate results and was less influenced by low age and lymphocytopenia than QFT-GIT in this population of immunodeficient children. These findings suggest that T-SPOT is a more accurate test for the identification of TB infection in young children with lymphocytopenia and should be preferred to QFT-GIT under such specific conditions.

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