Efficacy of three mycobacterial antigens in the serodiagnosis of tuberculosis.

Three different antigens were tested for detection of mycobacterial antibodies. The 3 antigens were mycobacterial saline extract (MSE), mycobacterial sonicate (MSO) and PPD. For detection, both the soluble antigen fluorescent antibody (SAFA) and the enzyme-linked immunosorbent assay (ELISA) tests were used. We used 88 serum samples (50 from clinically, radiologically and/or bacteriologically proven cases of tuberculosis, 8 from proven cases of leprosy and 30 from healthy controls). With MSE antigen, both the tests were found to be highly sensitive and specific. MSO antigen was found to give better results in ELISA than in SAFA. The sensitivity and specificity of ELISA as well as SAFA test was reduced when PPD was used as an antigen. However, both ELISA and SAFA tests revealed that the mean antibody level in the patients with active tuberculosis was significantly higher than that in the healthy controls, irrespective of the antigen used.