Detection of mycobacterial antigens in cerebrospinal fluid by enzyme-linked immunosorbent assay

By use of commonly available antibodies against Mycobacterium bovis BCG, Mycobacterium tuberculosis antigens can be detected by a rapid and sensitive double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). The ELISA was dose-dependent and capable of detecting as little as 4 ng of antigens. Absorbance for 5 patients with confirmed tuberculous meningitis ranged from 0.150 to 0.600 with a mean value of 0.271 +/- 0.190. For 134 non-meningitis control patients and 6 treated tuberculous meningitis patients, optical densities were 0.032 +/- 0.009 and 0.029 +/- 0.010, respectively. Specificity was demonstrated by the negative results (0.028 +/- 0.006) with bacterial and cryptococcal antigens. Maximum cross-reactivity with non-tuberculous mycobacterial antigens was less than 7%.