Comparison of tuberculin skin test with a whole-blood interferon gamma assay and ELISA, in HIV positive children and adolescents with TB.

We compared the usefulness of three methods designed to diagnose latent tuberculosis [TB]: interferon-gamma release assay [IGRA], such as QuantiFERON-TB Gold [QFT-G], Enzyme-linked immunosorbent assay [ELISA] serologic assay and tuberculin skin test [TST] for diagnosis of TB in human immunodeficiency virus [HIV]-1 infected children and adolescents, with microbiologically and/or histopathologically confirmed TB co-infection. The serum samples were obtained from 36 patients who were examined and tested by the three methods. The sensitivity was 38.8% for TST, 47.2% for IGRA (QFT-G) and 11.1% for ELISA. Out of 24 patients with severe immune suppression (CD4+ < 200 cells/ml), 6 had positive TST, i.e. sensitivity 25%, 10 positive QFT-G results, i.e. sensitivity 41.6%. 6 of the QFT-G results could not been determined. ELISA was positive only for one of them. Among the 12 patients without severe immune suppression (CD4+ > 200 cells/ml), 8 had positive TST, QFT-G was positive in 7 patients., 3 of QFT-G results could not been determined. ELISA was positive in 3/12 patients. Only 3 of these results were simultaneously positive with TST, QFT-G and ELISA. Our results demonstrated concordance between QFT-G and TST in HIV-infected children and adolescents diagnosed with TB. Since all the patients had active TB, it was not possible to calculate the specificity of the tests. ELISA had the lowest sensitivity, while QFT-G and TST sensitivities were comparable for the children and adolescents with CD4+ count >200 cells/ml. Further research is needed in HIV-1 positive children and adolescents with and without TB in order to validate rapid diagnosis methods for TB.