VALUE OF ELISA USING A60 ANTIGEN IN THE SERODIAGNOSIS OF TUBERCULOSIS

This study was set in a general, university hospital in the Canary Isl ands, with the objective to evaluate an enzyme-linked immunosorbent as say (ELISA) using A60 in the serodiagnosis of tuberculosis. Ige antibo dy to A60 was determined in 205 patients with active disease [149 cult ure-positive patients with pulmonary tuberculosis (positive sputum sme ar 94, negative sputum smear 55) and 56 patients with extrapulmonary t uberculosis], 20 patients with inactive disease, 22 patients with lepr omatous leprosy, and 51 controls. The mean levels of anti-A60 antibodi es were significantly higher in patients with active disease as compar ed with controls or patients with inactive disease. Differences were a lso found between tuberculous patients with pulmonary and extrapulmona ry disease. In patients with pulmonary disease, significant difference s were detected between smear-positive and smear-negative patients. Th e overall sensitivity of the test (cutoff 240 ELISA units) was 52.2%. The highest sensitivity was found among smear-positive patients with p ulmonary tuberculosis (67%) and the lowest among those with extrapulmo nary tuberculosis (32.1%). We conclude that ELISA for the measurement of IgG antibody to Mycobacterium tuberculosis antigen A60 could be of interest, specially in smear-negative cases and extrapulmonary tubercu losis.