Sensitivity and specificity of enzyme-linked immunosorbent assay in the detection of antigen in tuberculous meningitis cerebrospinal fluids

Abstract

A sandwich enzyme-linked immunosorbent assay was developed for its potential utility in the detection of antigen in the cerebrospinal fluid of patients with tuberculous meningitis. Cerebrospinal fluids examined included those from untreated (group Ia) and treated (group Ib) Mycobacterium tuberculosis meningitis, nonseptic central nervous conditions (group II) such as epilepsy, viral meningitis, and tetany, and nonmycobacterial septic meningitis (group III). The average levels of antigens determined and percent positive specimens, respectively, for each group were (group): Ia, 1.8 micrograms/ml and 75% positive; Ib, 0.37 microgram/ml and 36% positive; II, 0.036 microgram/ml and 100% negative; and III, 0.075 microgram/ml and 100% negative. The system developed employed hyperimmune polyclonal antibody raised against M. tuberculosis and Mycobacterium bovis BCG in burros and rabbits. Cross-reactivity by other mycobacterial species was very low; e.g., 5% for M. kansasii and less than 2% for M. intracellulare, M. avium, M. vaccae, and M. fortuitum. The test shows promise as a specific adjunct for the early diagnosis of tuberculous meningitis.