Detection of mycobacterial antigens in cerebrospinal fluid by enzyme-linked immunosorbent assay utilizing anti-mycobacterial saline extract antibodies.

Using anti-mycobacterial saline extract antibodies, Mycobacterium tuberculosis antigens can be detected in cerebrospinal fluid by a highly specific and sensitive double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). The ELISA was dose-dependent and capable of detecting as little as 6.0 ng of antigens. Specificity was demonstrated by negative results (0.063 +/- 0.008) with other bacterial and cryptococcal antigens (n = 9), and maximum cross-reactivity with other mycobacteria was less than 2.0%. Absorbance for six patients with confirmed tuberculous meningitis gave results ranging from 0.168 to 0.898 with a mean value of 0.393 +/- 0.248. For 172 nonmeningitis and nontuberculosis control patients and 6 treated tuberculous meningitis patients, optical densities were 0.064 +/- 0.001 and 0.057 +/- 0.007, respectively. Significant statistical difference (p less than 0.001) was found between the tuberculous meningitis and control groups.