A 50-year-old Chinese male presented to a local hospital with right ankle pain and limited mobility 23 months ago and underwent a synovectomy of the ankle. Specimen culture revealed brucellosis infection in sheep. The patient came to the department of Orthopaedics of our hospital 18 months ago because his symptoms did not improve. His case history indicated that he had worked in a Sheep farm for 9 months. We, therefore, suspected that he might have acquired Brucella infection through ingestion or contact with injured skin. A 37 C temperature, no sweating, weight loss, and no personal or family history of tuberculosis were all present on admission. Physical examination showed significant tenderness on the lateral side of the right ankle without fever. Blood flow to right toe is good, right ankle varus pressure test is positive. Laboratory tests were as follows: Hemoglobin (Hb) 136 g/L, Red blood cell count (RBC) 4.25x1012/L, White blood cell (WBC) 10.09x109/L accompanied by neutrophil elevation, Platelet 363x109/ L, Erythrocyte sedimentation rate (ESR) 31 mm/h, C-reactive protein (CRP) 32 mg/L. Rose-Bengal Plate Agglutination Test (RBPT) was positive.
Anteroposterior and lateral X-ray of the right ankle showed arrowed joint spaces (Figure 1A and B). CT showed multiple cysts were noted below the articular surface of the right ankle, and the articular surface of the talus collapsed (Figure 2A-D). MRI showed the right ankle joint space was significantly narrowed, the articular surface was coarse, the articular cartilage was thinned, the talus articular surface collapsed, and multiple cysts were found in the subchondral bone (Figure 3A-D). Joint synovial fluid of right ankle was extracted by joint aspiration and sent to the laboratory for Real-time PCR examination, and the results showed that there was B. melitensis in the synovial fluid (Figure 4). The HE staining of ankle fluid revealed inflammatory cell infiltration, while acid-fast staining was negative (Figure 5A and B). We concluded that the patient had recurrent Brucella ankle arthritis and was treated with doxycycline (0.1 g po bid), rifampicin (0.6 g po qd) and cefotaxime-sulbactam (2.25 g ivgtt q8h) for six weeks during hospitalization. ESR and CRP levels declined significantly after drug treatment, returning to normal levels of 17.00 mm/h and 7.88 mg/L, respectively.     
The right ankle movement of the patient was basically normal at discharge, and the pain was significantly reduced. Laboratory tests after drug treatment showed erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels of 17.00 mm/h and 7.88 mg/L, respectively, significantly decreased and returned to normal. At following-up 18 months later, the patient had no discomfort in the right ankle and all inflammatory markers were normal. RBPT was negative.