An agar--gel immunodiffusion test for detection of Brucella antibodies in human serum

A comparison was made of results obtained with a Brucella agar--gel immunodiffusion (AGID) test and the standard tube-agglutination test on 612 human sera. Agreement between the tests was 97% when the titer was 1:160 or higher. Of 448 sera that showed no agglutination titer, 447 were negative with the AGID test. Results of the AGID test were also compared to those obtained with the 2-mercaptoethanol (2-ME) agglutination test on 148 sera that demonstrated a standard tube-agglutination titer of 1:20 or higher. All sera with a 2-ME-agglutination titer of 1:40 or higher were positive with the AGID test. Of 123 sera that showed no 2-ME-agglutination titer, 21 were positive with the AGID test. Two of these 21 sera were obtained from patients with bacteriologically proven brucellosis, and eight were from abattoir employees with suspected but not bacteriologically proven brucellosis.