Serodiagnosis of Tuberculosis in Children Using A60 Antigen

Measurement of antimycobacterial antibody may be used as an accurate diagnostic tool in childhood tuberculosis. This study was conducted to evaluate the value of IgG, IgA, and IgM levels against A60 antigen by using ELISA method for diagnosis of tuberculosis. 238 children aged from 6 months to 18 years old, divided into 4 groups; group A(n=51),patients with documented diagnosis of tuberculosis; group B (n=75), patients who had close contact with TB patients; group C (n=51), patients with lung diseases other than tuberculosis; group D(n=40), healthy children. Serums of 4 different groups of patients were studied. Group A consisted of 22 smear positive, 24 smear negative, and 5 extrapulmonary tuberculosis patients. Sensitivity for bacteriologic study in smear positive cases was 51.2%. The mean levels of IgG, IgA, and IgM were significantly high in group A compared to other groups. IgM anti-A60 antibody had 70.6% sensitivity and 62% specificity for tuberculosis. Among the smear negative tuberculosis patients IgM anti-A60 had a sensitivity of 62.1%. Sensitivity of IgM anti-A60 in group B was 53.3%. The sensitivity of combined use of IgG and IgM was 70.6% in group A. The sensitivity of serologic diagnosis of A60 antigen is higher than bacteriologic findings (77.3% vs. 51.2%). A60-ELISA test is a simple and rapid diagnostic method, which can facilitate the diagnosis of tuberculosis. (Tanaffos 2002; 1(2): 15-19)