Rapid diagnosis of tuberculous meningitis by using an enzyme-linked immunosorbent assay to detect mycobacterial antigen and antibody in cerebrospinal fluid.

Rapid diagnostic tests for tuberculous meningitis are urgently needed because delayed treatment increases the already high mortality rate of this disease. Direct acid-fast staining of cerebrospinal fluid is the only quick method generally available, but it lacks sensitivity. Therefore, we evaluated the use of an enzyme-linked immunosorbent assay (ELISA) to mycobacterial antigen and antibody in the cerebrospinal fluid of 29 patients with proven tuberculous meningitis, 83 patients with nontuberculous central nervous system infections, and 15 normal controls. The specificity of the test was 96%; the four false-positive results all occurred in patients with bacterial meningitis. Fifteen (52%) of 29 patients with tuberculous meningitis had either a positive antigen or antibody ELISA test, which was significantly more than the number of patients testing positive by direct staining (two of 29 positive; P less than .01). We therefore recommend using an ELISA to detect antigen and antibody but caution that because of limited sensitivity a negative test result does not exclude the diagnosis of tuberculous meningitis.