Performance characteristics of the Euroimmun enzyme-linked immunosorbent assay kits for Brucella IgG and IgM

Brucella IgG and IgM ELISA kits manufactured by Euroimmun (Lubeck, Germany) were evaluated in a reference laboratory setting. Intraassay coefficient of variation (CV) values were ≤10% for positive sera and ≤12% for negative sera; interassay CVs were ≤12% for positive sera and ≤20% for negative sera. The tube agglutination test (TAT) was performed on 51 sera exhibiting various ELISA reactivity profiles. All 18 sera negative for both IgG and IgM by ELISA were TAT negative (titer <1:80), whereas 31 (94%) of 33 sera positive for IgG and/or IgM were TAT positive; the 2 discordant sera were IgG positive IgM negative by ELISA. None of 41 sera from healthy laboratory employees were ELISA IgG positive, whereas 1 (2%) of 41 was ELISA IgM positive. Similarly, 0 of 149 potentially cross-reactive sera (containing rheumatoid factor or antibodies to selected Gram-negative bacteria) was ELISA IgG positive, whereas 4 (3%) of 149 were ELISA IgM positive. These findings demonstrate the acceptable performance of the Euroimmun ELISAs for Brucella antibodies.