RESUMEN
Tuberculosis is one of the deadliest diseases over the world. Diagnosis of pulmonary- TB depends on combination various parameters. IGRA measure T cell release of IFN-gamma in response to M.TB antigen. WHO policy statement on IGRA use in low and middle countries is not established yet. The present study aimed to compare between tuberculin skin test [TST] and interferon gamma release assay [IGRA] in the diagnosis of active tuberculosis infection and study the effect of 3 months of first line of anti-TB therapy on the positivity of the IGRA test. 40 Egyptian patients were included in the study, and assigned as two groups; Group I comprised 20 patients with negative sputum for AFB by Ziehl-Neelsen stains with positive sputum culture for M.TB and Group II [IIa and lIb] that included 20 patients with positive sputum and Ziehl-Neelsen for AFB before and after 3 months of first line of anti-TB therapy. All patients were subjected to full history taking, clinical examination, X- ray chest, lab investigations, ESR measurements, microbiological tests and EL1SA measurement of Quantiferon-TB Gold. Lower significant values were found in group IIb than group IIa as regarding clinical parameters and 1[st] and 2[nd] hours ESR. IGRA test and TST showed sensitivity [91.18%, 76.4%], specificity [83.33%, 66.67%], positive predictive value [96.88%, 92.86%], negative predictive value [62.5%, 33.3%] and accuracy of [90%, 75%] respectively. IGRA results had no statistical significant differences between the studied groups with poor agreement with TST [[k]= 0.025].1GRAS test had high sensitivity' and specificity in diagnosis of active TB. More studies are needed to evaluate the effect of anti-TB therapy on IGRA level