Diagnostic Significance of the Serologic Test Using Multiple Antigens of Mycobacterium Tuberculosis by ELISA

Kim, Dae Yun; Choi, In Hwan; Park, Seung Kyu; Cho, Shang Rae; Song, Sun Dae

Abstract

BACKGROUND: Diagnosis by smear and/or cultures of the Mycobacterium tuberculosis from body fluid or biopsy specimen is "Gold standard". However the sensitivity of the direct microscopy is relatively l ow and culture of mycobacteria is time consuming. Despite an explosion in the techniques of rapid identification of mycobacteria by molecular genetic means, it is laborious and expensive and then rapid, inexpensive serodiagnosis is interested in diagnosis of tuberculosis. But sensitivity and specificity of known serologic antigen is not full sufficient level and then new antigen develop and combination cocktails of new develped antigens by ELISA are needed. METHOD: To compare the efficacy of different mycobacterial specific antigen and to assess the applicability of the combination of several different antigens in the diagnosis of tuberculosis, five ELISA tests derived 14KDa, 16KDa, 19KDa, 23KDa, 38KDa were evaluated in 57 active pulmonary patient and 24 inactive post-therapy follow up patient and 48 normal control.
RESULTS
The optical densities of ELISA test with 14KDa, 16KDa, 19KDa, 23KDa, 38KDa were significantly higher in active tuberculosis cases than in normal control(P<0.001, P<0.001, P<0.027, P<0.001, P<0.001) and those with 16KDa, 38KDa were significant higher in active tuberculosis cases than in inactive post-therapy follow up cases(P<0.01, P<0.001) and those of 14KDa, 16KDa, 23KDa, 38KDa were significant higher in inactive post-therapy follow up cases than in normal control(P<0.008, P<0.01, P<0.006, P<0.001). The sensitivity of 14KDa, 16KDa, 19KDa, 23KDa, 38KDa in active pulmonary patient cases was 42.1%, 43.9%, 15.8%, 28.0%, 70.2%, respectively and the specificity of 14KDa, 16KDa, 19KDa, 23KDa, 38KDa in active pulmonary patient cases was 95.8%, 95.8%, 91.7%, 89.6%, 93.8%, respectively. The sensitivity and specificity of combination 38KDa with 16KDa was 87% and 93.7%.
CONCLUSION
The sensitivity andspecificity of new antigens for serodiagnosis of the tuberculosis still remains limited at around 70%, which makes its a poor diagnostic tool for disease confirmation. A combination of cocktail antigens provided by cut-off value adjustment for serodiagnosis of tuberculosis some improved diagnostic yield than single antigen serologic test.