Abstract: Objective: To investigate the value of interferon gamma release (IGRA) in the diagnosis of bacterial-negative pulmonary tuberculosis. Methods: A total of 93 patients with bacterial-negative tuberculosis and 40 healthy volunteers were enrolled in this study. Heparin sodium anticoagulant whole blood was collected. IGRA kit was used to detect the plasma IFN-γ level. Serum samples were collected for detection of Mycobacterium tuberculosis antibody(TBAb) by ELISA kit. Patients were divided into the elderly group and the young group for comparative analysis. Routine test indice ADA, erythrocyte sedimentation rate and lymphocyte count were performed. Results: The positive rate of IGRA was 84.94%, the sensitivity was 84.94%, the specificity was 90.00%, the positive predictive value was 95.18% and the negative predictive value was 72.00%. The positive rate of TBAb diagnosis was 52.69%, the sensitivity was 52.69%, the specificity was 85.00%, the positive predictive value was 67.20% and the negative predictive value was 40.96%. Rate of diagnosing tuberculosis using two methods, was statistically significant. There was no difference in age when using IGRA assays. There was significant differences in erythrocyte sedimentation rate between the two groups. Conclusion: Compared with ELISA, IGRA has higher sensitivity, specificity and positive predictive for diagnosing bacterium negative tuberculosis.

Key words: Interferon-gamma release assays, Tuberculosis, Bacteria-negative pulmonary tuberculosis, Antibody, Diagnosis