A competition ELISA for the detection of mycobacterial antigen in tuberculosis exudates.

An enzyme-linked immunosorbent assay (ELISA) was designed to detect the inhibition of BCG-anti-BCG reactions by soluble antigens of Mycobacterium tuberculosis. Eighty-four samples were tested of which 59 were of cerebrospinal fluid (CSF) (25 control, 10 bacterial, 14 viral and 10 tuberculous meningitis); and twenty-five were of pleural or ascitic fluid (15 tuberculous exudates and 10 non-tuberculous samples). A statistically significant difference (p less than 0.01) was found between the tuberculous and control groups. The sensitivity and specificity of this test was almost 100%--no false negatives and only one false positive result occurred among the samples of CSF tested.