Diagnostic value of measuring BCG sonicate antigen and anti-BCG antibodies in the cerebrospinal fluid and blood of patients with tuberculous meningitis.

Fourteen cerebrospinal fluid (CSF) and paired blood samples were obtained from patients with tuberculous meningitis, seven with positive culture and seven clinical/laboratory diagnosis. Another 14 paired specimens served as control, including 7 infectious meningitis and 7 non-inflammatory neurological diseases. Four groups were thus classified, including confirmed and suspected patients, and controls with infectious meningitis and neurological diseases. Measurements of Bacillus Calmette-Guérin (BCG) sonicate antigen and IgG antibody were performed using enzyme-linked immunosorbent assay. Generally, CSF BCG sonicate antigen level and anti-BCG sonicate antibody of patients with tuberculosis meningitis were higher than in control groups; greater antigen levels were found in confirmed patients than in non-inflammatory subjects (p less than 0.05), and in suspected patients than in infectious and non-inflammatory subjects (p less than 0.05 and p less than 0.01). For serum anti-BCG sonicate levels, confirmed patients had higher antibody value than non-inflammatory subjects (p less than 0.05). To conclude, detection of high levels of both BCG sonicate antigen and antibody in CSF and blood samples shows great value in the diagnosis of tuberculous meningitis. However, given the limited samples of the current research, more data are needed to elucidate the sensitivity and specificity of such tests.