Serodiagnosis of tuberculosis by an enzyme-linked immunosorbent assay using mycobacterial antigen 60

This study was undertaken to assess the diagnostic utility of an enzyme-linked immunosorbent assay using mycobacterial antigen 60 in patients with pulmonary tuberculosis. This test was applied to 210 adults, including 111 patients with active pulmonary tuberculosis, 80 control subjects and 19 patients with inactive pulmonary tuberculosis. Although the serums from the patients with active tuberculosis has a higher mean value of IgG antibody concentration than the control group, there was a considerable overlap of serum IgG antibody level between the two groups. 200 ELISA unit (EU) was established as a reasonable cut-off value, which gave an 80.2% (89/111) sensitivity for the group with active pulmonary tuberculosis and a specificity of 76.3% (61/80) only for the control group. The patients with inactive pulmonary tuberculosis had a positive rate up to 47.4% (9/19) when 200 EU was chosen as a cut-off value.