Reduction of non-specific reactions to the Brucella abortus serum agglutination test by the addition of EDTA.

Serum samples taken from cattle known to be infected with Brucella abortus, and samples routinely collected as part of the brucellosis eradication scheme were tested by the serum agglutination test (SAT), complement fixation test (CFT) and the SAT modified by the addition of ethylene diamine tetra-acetic acid (EDTA). In 64 per cent of the samples giving an SAT titre greater than 100 iu, but a CFT titre 8.3 icftu or less, the agglutination reaction was sufficiently affected by the action of EDTA for the titre to drop to below 100 iu. Only 5 per cent of samples giving an SAT titre greater than 100 iu and a CFT titre of 20 icftu or greater were affected in a similar manner by EDTA, and none of the 29 sera taken from known infected animals showed a drop in titre to below 100 iu, although some with titres greater than 500 iu did show significant EDTA sensitivity.