Sensitivity of EIA in the diagnosis of tuberculosis using 38-kDa antigen

Patients, who reported to Government Medical College Hospital, Chandigarh with suspected signs and symptoms of pulmonary tuberculosis, were examined. Their sputum was investigated for the presence of acid-fast bacilli, using the routine Ziehl-Neelsen staining, for 3 consecutive days. The positive cases were referred for treatment and the rest were referred for supplementary tests like x-ray, Mantoux test, FNAC and the presence of IgG antibodies in their serum against recombinant 38-kDa antigen derived from Mycobacterium tuberculosis, using micro-ELISA plates. It was found that 37.8% of the cases who were negative for acid-fast bacilli found to be positive for the presence of antimycobacterial IgG antibodies with an antibody titre greater than the cut off value in addition to one of the above mentioned positive supplementary finding. Hence, EIA for tuberculosis is more sensitive as compared to the routine acid-fast bacilli staining.