Leukocyte count in the synovial fluid of children with culture-proven brucellar arthritis

Brucellosis is an important cause of paediatric septic arthritis in endemic areas. Because the Gram stain is frequently negative and culture results are unavailable at the time of the patient's admission, the diagnosis of brucellar arthritis is usually entertained on the bases of epidemiological considerations and cytological examination of the synovial fluid aspirate. The aim of this study was to assess the sensitivity of a synovial fluid leukocyte count >50 000 WBC/mm ³ for detecting culture-proven brucellar arthritis in children. The medical records of all children with brucellar arthritis diagnosed since 1994 in a hospital serving an endemic area for brucellosis in southern Israel were reviewed. Nine patients (six males and three females), aged 3-14 years, were identified. A single joint was affected in all patients. The median leukocyte count in the synovial fluid was 9500 WBC/mm ³ (range 300-61 500 WBC/ mm ³), and in eight of the nine patients it was less than 50 000 WBC/mm ³. Brucella melitensis was recovered from the synovial fluid culture in all patients. The diagnosis of brucellar septic arthritis cannot be excluded on the basis of a low leukocyte count in the joint aspirate. A high index of suspicion and use of modern culture techniques are recommended to improve the diagnosis of brucellar arthritis.