Interferon-gamma release assays (IGRA) for latent tuberculosis infection (LTBI) in children

Background: IGRA, QuantiFERON®-TB Gold in-tube (QFT-GIT) & T-SPOT.TB®(T-Spot), are widely used to detect LBTI in adults. There is paucity of data regarding their use in children ( Methods: We retrospectively reviewed all the IGRA tests performed in children, for contact & new entrant screening, in our TB service between 2008 & 2010, to look at our indeterminate rates. Results: A total of 188 IGRA tests were performed. T-Spot was undertaken almost exclusively in children under 1 year. None of our cohort had indeterminate IGRA results with QFT-GIT or T-Spot. None of the children were diagnosed with active TB (multiple samples were sent for TB culture from 4 children). Conclusion: A definitive IGRA result is achievable in otherwise healthy children with close liaison between clinical and microbiology staff, prompt transfer of blood samples and incubating QFT-GIT samples within 4 hours of collection. Reference: 1Ling, D.I. et al. Immune-based diagnostics for TB in children:what is the evidence?Paed Resp Reviews. 2011;12(1):9-15.