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

Abstract

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 ≥1:320 and a 2-ME of ≥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 ≤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 ≥1:320 were seen in 41 (23.4%), 22 (12.6%), 7 (4%), and 6 (3.4%) cases, respectively, whereas 2-ME titers ≥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 ≤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 ≤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.