Evaluation of a Brucella enzyme immunoassay test (ELISA) in comparison with bacteriological culture and agglutination

An ELISA test for IgG and IgM antibrucella antibodies was found to be effective in diagnosis of human brucellosis. Assays for IgG and IgM in 30 culture-positive cases gave significant ELISA values. By the standard agglutination test, 10% of these cases gave readings less than 1:160. These are considered insignificant, taking 1:160 as the accepted cut-off value. Moreover, in an extra 135 samples from suspected brucella cases, where only serology was requested (77.6% of all cases), 7.4% were found to have IgM brucella antibodies by ELISA. In all of these, the corresponding agglutination titres were less than 1:80 and hence reported as insignificant. We report the detection of IgG and IgM antibodies in samples from patients with both acute and chronic disease. In few patients with acute disease, only IgM was detected. These findings are discussed in comparison with earlier studies. Finally, the ELISA test, in addition to measuring antibody classes directly, also detects incomplete antibodies. By this, it can efficiently replace the 2 mercaptoethanol test (2ME) and the Coomb's antihuman-globulin test. This saves considerable laboratory cost and time.