BACKGROUND: Tuberculous meningitis (TBM) is still a serious cause of morbidityand mortality in developing nations, and the timing of treatment is the most crucial factor affectingthe ultimate outcome. To establish a rapid diagnosis, we used Single Radial Immuno-Diffusion (SRID) todetect circulating mycobacterium antigen in the CSF of patients with clinically suspected TBM.MATERIAL/METHODS:Single radial immunodiffusion is the simplest of all immunotechniques for the quantitative determinationof antigen or antibody. CSF was collected by standard lumbar puncture. Antiserum was raised against CSFfrom clinically suspected TBM patients by standard Immunization procedures.RESULTS: The developed protocolwas tested with 73 CSF samples collected over a period of one year. The assay gave 94% sensitivity forthe detection of mycobacterium antigen in the CSF of patients with clinically suspected TBM.CONCLUSIONS:This study suggests that single radial immunodiffusion is useful for quantitative as well as qualitativedetermination of mycobacterium antigen. The developed technique is of potential value in the laboratorydiagnosis of TBM.

Keywords: Case-Control Studies, Comparative Study, Immunodiffusion, Sensitivity and Specificity, Tuberculosis, Meningeal