2-mercaptoethanol Brucella agglutination test: usefulness for predicting recovery from brucellosis

Ninety-two patients with brucellosis were studied for 18 months, and 15 to 29 sera from each patient were tested by the standard tube brucella agglutination test and by the 2-mercaptoethanol (2ME) brucella agglutination test. The standard tube test remained positive (greaterr than or equal to 160) for 1.5 years in 44 of the 92 patients (48%), despite adequate antibiotic treatment. The 2ME titers remained positive (greater than or equal to 160) in only 8 of 92 patients (9%) after 1 year, and in only 4 of 92 patients (4%) after 1.5 years. Positive 2ME titers 1 year after initiation of treatment were present in 3 of 10 patients (30%) with drug allergies that interfered with antibiotic treatment, in contrast to only 5 of 82 patients (6%) without any allergies (P = 0.039). None of 84 patients with negative 2ME titers after 12 months of treatment had significant signs or symptoms of brucellosis, and none developed chronic brucellosis. In contrast, four of eight patients with positive 2ME titers after 12 months of treatment still had signs and symptoms of brucellosis and required further treatment. The 2ME test is superior to the standard tube test in determining the adequacy of antibiotic therapy, and a negative 2ME test is strong evidence against a diagnosis of chronic brucellosis.