Evaluation of a dual-antigen ELISA test for the serodiagnosis of tuberculosis

Two antigen preparations from Mycobacterium tuberculosis and M. bovis, respectively, were used in an enzyme-linked immunosorbent assay (ELISA) to quantitate the level of IgG antibodies in samples of 169 sera obtained in India from 75 patients with pulmonary tuberculosis and from 94 controls. The results of the two ELISA tests were integrated using defined criteria. All the controls were correctly classified by this dual-ELISA approach and only two patients were categorized as false negatives. The method has a specificity of 1.00 and a sensitivity of 0.974, while the gain in the certainty of diagnosis was 1.974, only slightly less than the ideal value of 2.00.