Enzyme-linked
immunosorbent assays (ELISA) of
immunoglobulin G antibody to
Mycobacterium tuberculosis antigen 5 and
tuberculin purified
protein derivative (
PPD) were assessed for the serodiagnosis of
tuberculosis in 41 patients with active
tuberculosis, 19 patients with inactive
tuberculosis, and 59 healthy control subjects. Patients with active
tuberculosis were studied serially at monthly intervals following the initiation of
therapy. When contrasted with our earlier studies of sera from patients in Bolivia and Argentina, serum titers in Cleveland patients with active
tuberculosis were somewhat lower. Geometric mean titer in patients with active
tuberculosis was 1:68 with
antigen 5 and 1:46 with
PPD. Titer was correlated with patient age, male sex, extent of
tuberculosis, and history of prior
tuberculosis. However, these associations were not statistically significant. During monthly follow-up for 16 months after the initiation of
therapy, ELISA titers remained essentially stable. Thus, no convincing evidence was acquired to support the hypothesis that higher titers in sera from South American patients related to more chronic or more extensive disease. Receiver operating characteristics of ELISA with
antigen 5 were better than those obtained using
PPD and were similar to those reported by others for sputum smear. In a situation where
tuberculosis screening is warranted, ELISA with
antigen 5 might have a place if it recognizes a different population than does sputum smear.