Determining Mycobacterium tuberculosis Infection among BCG-Immunised Ugandan Children by T-SPOT.TB and Tuberculin Skin Testing

作者：Nkurunungi Gyaviira^*; Lutangira Jimreeves E; Lule Swaib A; Akurut Hellen; Kizindo Robert; Fitchett Joseph R; Kizito Dennison; Sebina Ismail; Muhangi Lawrence; Webb Emily L; Cose Stephen; Elliott Alison M

来源：PLos One, 2012, 7(10): e47340.

DOI：10.1371/journal.pone.0047340

Background: Children with latent tuberculosis infection (LTBI) represent a huge reservoir for future disease. We wished to determine Mycobacterium tuberculosis (M.tb) infection prevalence among BCG-immunised five-year-old children in Entebbe, Uganda, but there are limited data on the performance of immunoassays for diagnosis of tuberculosis infection in children in endemic settings. We therefore evaluated agreement between a commercial interferon gamma release assay (T-SPOT.TB) and the tuberculin skin test (TST; 2 units RT-23 tuberculin; positive defined as diameter %26gt;= 10 mm), along with the reproducibility of T-SPOT. TB on short-term follow-up, in this population. %26lt;br%26gt;Methodology/Principal Findings: We recruited 907 children of which 56 were household contacts of TB patients. They were tested with T-SPOT. TB at age five years and then re-examined with T-SPOT. TB (n = 405) and TST (n = 319) approximately three weeks later. The principal outcome measures were T-SPOT. TB and TST positivity. At five years, 88 (9.7%) children tested positive by T-SPOT. TB. More than half of those that were T-SPOT. TB positive at five years were negative at follow-up, whereas 96% of baseline negatives were consistently negative. We observed somewhat better agreement between initial and follow-up T-SPOT. TB results among household TB contacts (kappa = 0.77) than among non-contacts (kappa = 0.39). Agreement between T-SPOT. TB and TST was weak (kappa = 0.28 and kappa = 0.40 for T-SPOT. TB at 5 years and follow-up, respectively). Of 28 children who were positive on both T-SPOT. TB tests, 14 (50%) had a negative TST. Analysis of spot counts showed high levels of instability in responses between baseline and follow-up, indicating variability in circulating numbers of T cells specific for certain M.tb antigens. %26lt;br%26gt;Conclusions/Significance: We found that T-SPOT. TB positives are unstable over a three-week follow-up interval, and that TST compares poorly with T-SPOT. TB, making the categorisation of children as TB-infected or TB-uninfected difficult. Existing tools for the diagnosis of TB infection are unsatisfactory in determining infection among children in this setting.

• 出版日期2012-10-15