Rapid diagnosis of tuberculous meningitis by a dot-immunobinding assay

In this study, a dot-immunobinding assay (Dot-Iba) was standardized to measure circulating antimycobacterial antibodies in the cerebrospinal fluid (CSF) specimens for the rapid laboratory diagnosis of tuberculous meningitis (TBM). Specific CSF-IgG antibody to Mycobacterium tuberculosis from a culture proven patient with TBM was isolated and coupled with activated Cynogen bromide-Sepharose 4B. Using an immunoabsorbent affinity chromatography, 14 kDa antigen present in the culture filtrates of M. tuberculosis was isolated and this antigen was used in the Dot-Iba, to quantitate specific antimycobacterial antibodies in CSF specimens. The Dot-Iba gave positive results in all the 5 culture proven patients with TBM and gave no false positive results in CSFs from patients with partially treated pyogenic meningitis. Dot-Iba developed in our laboratory is a simple, rapid and specific method and more importantly suited for the routine application in laboratories with limited resources.