Follow-up standard agglutination and 2-mercaptoethanol tests in 175 clinically cured cases of human brucellosis.

Background: The standard agglutination (SAT) and 2-mercaptoethanol (2-ME) tests are usually used in the follow-up of treated cases of human brucellosis. The purpose of this study was to monitor the levels of these tests, two years after clinical cure in cases of brucellosis.

Methods: From April 2003 to September 2008, 175 clinically cured cases of brucellosis (103 males, 72 females) were evaluated. Diagnosis of brucellosis was established with a SAT of > or =1:320 and a 2-ME of > or =1:80, with clinical symptoms and signs compatible with brucellosis. SAT and 2-ME were retested at the end of therapy and at 3-monthly intervals for two years. Serologic cure was considered in the event of a SAT titer decrease to < or =1:160 or a 2-ME decrease to<1:80.

Results: The mean age of study patients was 31 +/- 13.5 years. At 6, 12, 18, and 24 months after treatment, SAT titers > or =1:320 were seen in 41 (23.4%), 22 (12.6%), 7 (4%), and 6 (3.4%) cases, respectively, whereas 2-ME titers > or =1:80 were seen in 51 (29.1%), 24 (13.7%), 12 (6.9%), and 8 (4.6%) cases, respectively. The probability of serologic cure for patients with SAT titers < or =1:640 was higher than for those >1:640 (95% confidence interval (CI) 2.5-3.47, p=0.023). The probability of serologic cure for patients with 2-ME titers < or =1:320 was higher than for those >1:320 (95% CI 2.48-3.5, p=0.04).

Conclusions: SAT and 2-ME may be found in significant titers in less than 5% of clinically treated cases after two years. Serologic cure for both tests with lower titers were higher than with higher titers.