Comparison of Tuberculin skin test and Quantiferon-tb gold test at the diagnosis of tuberculosis in the childhood peryod

Approximately 1/3 of world population is infected by mycobacterium organism. Earlier and accurate diagnosis is vital in the control and therapy of tuberculosis infection. Active tuberculosis disease may develop in %10 of patients with LTBI( Latent Tuberculosis Infection) in any period of their lifetime. Ratio of active tuberculosis development is higher in childhood period. Diagnosis of tuberculosis and extrapulmoner tuberculosis give rise to some diffuculties and may cause confusion in childhood period.False negative and positive results may come into view in TST (Tuberculine Skin Test). There are some hopeful studies to offer more suitable diagnosis methods that has no controversial events as TST about its sensitivity, specifity and interpretation and that would not effect from BCG vaccination.QuantiFERON-TB Gold (Cellestis Ltd., Carnegie, Victoria, Australia) test measuring IFN gamma levels secreted against to ESAT-6 ve CFP-10 antigens of RD1 gene zone of M.tuberculosis by ELİSA method is used in our study.Blood samples were collected from 300 children. Our study revealed out that QTF-G test is more sensitive (%92.72, %56.36) and spesific(%81.63, %60.71) than TST in the diagnosis of tubersulosis infection. QTF-G test was more spesific in whole groups. No common antigens are present between QTF-G test and BCG, that is way results of QTF-G test are not effected by BCG vaccination. QTF-G test is more suitable to establish accurate diagnosis and initiate therapy.In conclusion, ıt would be proper to utilize QTF-G test together with TST and/or to confirm TST in countries that BCG vaccination is routinely applicated as it is current in our country because TST and BCG has positive interaction in patients with higher risk and QTF-G test, due to its high sensitivity and specifity, also would be more practical for children patients that has high suspicion of tuberculosis infection but may not confirmed by direct microbiological methods (Direct microscopy, culture).