Brucellosis: a treatable cause of monoarthritis.

A 16-year-old Mexican-American boy presented with acute brucella sacroileitis. The diagnosis was based on a significantly elevated agglutination titer and confirmed by the growth of B. melitensis after four weeks incubation in blood culture. The patient recovered completely after six weeks of Tetracycline therapy. Because Brucella infection responds to treatment well, this infection is important in the differential diagnosis of arthritis, especially in an area endemic for Brucella. The readily available serologic techniques should be used to support the diagnosis, while recognizing that because of the slow growth rate of B. melitensis, the appropriate laboratory procedure is essential.