Enzyme-linked immunosorbent assay for brucella antigen detection in human sera

A sandwich enzyme-linked immunosorbent assay (ELISA) with monoclonal antibody coupled to the solid phase was evaluated for the detection of brucella antigen in serum samples. Under optimum conditions, 100 brucella cells/well or 10(5) fg/ml of lipopolysaccharide (LPS) were detected in spiked specimens. The standardised assay was performed on 1607 sera from random blood donors, 146 patients with brucellosis, 20 persons in high risk groups and 264 sera from patients with diseases other than brucellosis. Sensitivity was 100% compared with positive blood culture, and 44% compared with serological tests for brucella antibodies. Specificity was 99.5% among random blood donors and 99.2% in the patient population. These data showed a strong agreement between ELISA antigen detection and blood culture for the detection of brucella positive blood samples. Moreover, the results indicated that antigen detection by ELISA could be an acceptable alternative to blood culture for the diagnosis of brucellosis.