Detection of mycobacterial antigens in cerebrospinal fluid of patients with tuberculous meningitis by enzyme-linked immunosorbent assay.

Culture and identification of Mycobacterium tuberculosis in cerebrospinal fluid (CSF) of patients with tuberculous meningitis is slow, and prognosis depends on early diagnosis and treatment. An enzyme-linked immunosorbent assay with commercial BCG and anti-BCG was designed to detect mycobacterial antigens in human body fluids. Absorbance at 405 nm was measured and readings greater than or equal to 0.20 were considered positive. The readings were above 0.20 for four patients with confirmed tuberculous meningitis and nine of twelve patients with probable tuberculous meningitis. In all but one of ten patients with meningitis of other causes and in eleven control subjects the readings were below 0.20. The specificity of the test was 95% and its sensitivity 81.25%.