| BackgroundRecently, the incidence of pulmonary tuberculosis as an ancient disease has been rising greatly in our country. Therefore, an indicator of higher diagnostic sensitivity and specificity is needed because the positive rate of tuberculosis bacili smear or bacterial culture is so low. In recent research, T cells (IFN-y) can be obtained by the stimulation of the early secretory antigen (ESAT-6) and cultural filtration protein (CFP) as tuberculosis specific antigens. Therefore, the analysis of IFN-y release (T-IGRAs) is applied in the field of fast clinical diagnosis of mycobacterium tuberculosis infection.PurposeThe enzyme-linked immunosorbent assay was employed to detect the concentration of y-interferon (IFN-y) in human whole blood specimens, which can be obtained by the stimulation of mycobacterium tuberculosis specific antigen in vitro. Then, we can estimate the existence of the specific T cell immune response for mycobacterium tuberculosis.ObjectsBased on the tuberculosis diagnosis standard issued by the ministry of health of the People’s Republic of China on January16,2008, we collected51patients with pulmonary tuberculosis hospitalized in respiratory department,Shandong provincial hospital from June2013to January2014, of whom there were14cases confirmed diagnosed by positive sputum smear or pathology and37clinical diagnostic cases. As control experiment, we selected54cases of hospitalized patients with other respiratory diseases, excluding pulmonary tuberculosis after follow-up, or getting an improvement by other treatments (without anti-TB-treatment).MethodsFirst, the patients were on an empty stomach on the second morning admitted to hospital. Secondly, whole blood samples of the patients were collected not less than4mL within2hours by using heparin anticoagulating vacutainer. Thirdly, the whole blood samples were added into three culture tubes by the order of N, T, P as shown in the table to detect gamma interferon concentration. At last, comparing the rates of TB group with the control group, the difference between the two groups can be obtained by SPSS, which has statistical significance. Atthe same time, we detected blood sedimentation, tuberculosis antibody, and c-reactive protein in some patients of the experimental group, to decide their values for diagnosis ofactive tuberculosis.Results1. Of the total14cases confirmed diagnosed as pulmonary tuberculosis, TB-IGRA results of11cases show positive, indicating that the sensitivity is78.57%. Of the37cases clinical diagnosed as pulmonary tuberculosis, TB-IGRA results of30cases show positive, which indicates the sensitivity is81.08%. Therefore, the total sensitivity is80.39%(CI69.49%-91.29%).2. Of the54cases in controlled group, TB-IGRA results of5cases show positive, which shows that the specificityis90.74%(CI83.01%-98.46%).3. Based on the above results, the positive predictive value is89.13%and negative predictive value is83.05%. Moreover, Youden index is0.7113, with positive likelihood ratio being8.68and negative likelihood ratio being0.22.4. Sensitivity of tuberculosis antibody is14.29%(CI2.69%-28.01%), the total positive rate of blood sedimentation is95.65%,and the positive rate of CRP is84%.Conclusion1. The specificity of this study is high, which means the excluding diagnostic value of this test for tuberculosis is great. The relatively poor sensitivity means this test is suitable for auxiliary diagnosis of active tuberculosis.2. The authenticity of this study is good, according to high Youden index.3. Sensitivity of IGRA for the diagnosis of active tuberculosis is much higher than tuberculosis antibody.4. Joint detecting IGRA, blood sedimentation, c-reactive protein and other inflammatory indexes can improve the accuracy to detect active TB and can judge infection phase of patients. |
PDF Full Text Request