Evaluation of an ELISA kit for the Serodiagnosis of Pulmonary Tuberculosis by Using Mixed Antigens of Mycobacterium Tuberculosis

Park, Seung Kyu; Kim, Phil Ho; Kim, Seung Chul; Choi, In Hwan; Song, Sun Dae; Cho, Sang Nae

Abstract

BACKGROUND
Recently, serologic techniques for tuberculosis have been developed and some of them, which are focusing on detection of serum antibodies mainly directed against specific 38-kDa Mycobacterium tuberculosis, have already been introduced into the market. In this study, diagnostic significance of a new serologic test(ELISA kit) for pulmonary tuberculosis was evaluated.
METHODS
Serologic test with newly developed ELISA kit was performed upon 474 individuals, who include 333 active pulmonary tuberculosis patients, 80 healthy cases, and 61 tuberculosis contact cases. This serologic test was based on the ELISA technique and designed to detect antibodies to mixed complex antigens including 38-kDa, which were developed by Erume Biotech Co.,Seoul.Active pulmonary tuberculosis was diagnosed by sputum AFB smear and culture methods.
RESULTS
The seropositivities using this ELISA kit were 82.1% and 73.6% in smear-positive and negative groups among active pulmonary tuberculosis, respectively. And, it also showed that seronegativities were 97.5% and 85.2% in healthy and contact groups, respectively. As a whole, the results of our study suing the ELISA kit as a diagnostic methiod for pulmonary tuberculosis showed 80.0% sensitivity for active pulmonary tuberculosis, 97.5% specificity, 96.1% positive predictive value, and 65.0% negative predictive value when the prevalence of tuberculosis in the samples was 60.1%.
CONCLUSION
Our results reveal that the detection of antibody its reaction with 38-kDa antigen of M.tuberculosis is not sufficient to be accepted as single diagnostic method for pulmonary tuberculosis. However, they suggest that ELISA kit may be considered as an adjunctive test to standard diagnostic techniques of pulmonary tuberculosis.