The comparison of the efficiency of the gamma interferon assay and tuberculin skin test for the diagnosis of tuberculous infection in children

Aim: Tuberculin skin test (TST) is used in many years for early diagnosis of latently infected with Mycobacterium tuberculosis. However, the TST is not sufficiently spesific and sensitive. In recent years, interferon gamma assays (IFN ? ?) provide new tool for latent tuberculosis infection diagnosisIn this study we aimed to the compare the results of TST and a T-cell-based test that based on ELISPOT technic TSPOT.TB test (Oxford Immunotec, Oxford, UK), for tuberculosis infection in children exposed to pulmonary tuberculosisMethods: Sixty children were enrolled into the study. The contacts were divided as close and far contact, BCG scar number, BCG vaccination status, exposure and coughing time, source case number, crowding index and TST diameters. ELISPOT, TST and chest radiography were obtained. Analyses were performed using SPSS version 16.0Results: Thirteen (22 %) of 60 contacts tested were TST positive, 32 (53 %) were TSPOT.TB positive. Overall agreement between two tests was poor (? = 0.32) with concordance (65 %). When TST was used for basic standart, sensitivity of TSPOT.TB was 92.3 %, specifity was 57.4 %. While crowding index and increase of source case number was strongly associated with the risk of TST positivity, the increase of source case number was only associated with the risk of TSPOT.TB positivity according to multivariate risk analysisDiscussion: The IFN-? assay is a better indicator of the diagnosis of tuberculosis infection than TST. Especially, it was important to use these tests with together for detection to latent tuberculosis infection in far contacts for early diagnosis. But this finding need to be verified in larger studies that contain more cases.