Comparision of tuberculin skin test and T-spot? .TB test in detection of latent tuberculosis infection

SUMMARYLTBI is very important in the tuberculosis infection epidemiology because 10% ofLTBI have an active tuberculosis infection in a period of their life. There has been noimprovement in the diagnosis of LTBI for more than a century. TDT whichs? specificitysensitivity and explication is contentious is used in the diagnosis. The result of the studiesthat the immune response to RD1 gene region spesific antigens to M. tuberculosis is hopefuland has been identified newly.IFNγ which occurs by an immune response to RD1 gene region proteins ESAT-6,CFP-10 is analyzed with ELISPOT in our study. For this aim, ?T-SPOT™ .TB? (Oxfordİmmunotec Ltd. Oxon/England) commercial kits were used. The derivated results werecompared with the TDT results of the same subjects.In this study, we determined that T-SPOT test is significantly more sensitive (92.9%,78.6%) and more spesific (89.3%,46.4%) than TDT in diagnosis of tuberculosis infection.Among the risk groups, the concordance rate detected between BCG and TDT (57.4%) washigher than the one between BCG and T-SPOT(27%). The highest concordence rate amongthe tests was detected as 85.7% (K= 0.681 (p 0.001)) in Group 1 which was including activepulmonary tuberculosis cases. Despite, the low concordance rate between the two tests inGroup 3 (63.3% (K=0.305 (p=0.006)), this rate was significantly higher than the rate inGroup 2 .( 53.6 % (K= 0.011 p 0.05)).Consequently, among the countries like us where the vaccination is routinly applied,this test may be used with TDT or to confirm TDT results, because of the high positiveconcordance rate (41.0%) between the TDT and BCG among the high risk groups, theapplication of T-SPOT™.TB test is appropriate and when the diagnosis is clinicallypredicted but could not be diagnosed by microbiological assays (direct microscopy, culture)it is thought that the application is useful because of high sensitivity and specifity.39