Multifocal Brucellosis in a Young Patient: When a Non-inflammatory Knee Effusion Hides Systematic Complications

Brucellosis, a prevalent zoonosis transmitted through unpasteurized dairy products or contact with infected animals, typically presents with fever, malaise, fatigue, hepatic involvement, and various osteoarticular manifestations. However, it rarely presents with hepatic microabscesses and osteomyelitis. We report a case of a 26-year-old female with no known comorbidities who presented with complaints of fever and right knee swelling for three days. On clinical assessment, her pulse was 120 beats per minute, respiratory rate was 18 breaths per minute, blood pressure was 80/54 mmHg, and temperature was 38°C. Musculoskeletal examination revealed knee effusion only. The systemic examination was unremarkable except for an innocent murmur in the heart. Laboratory results showed hemoglobin 6.7 g/dL, mean corpuscular volume 60, white blood cell count 3.29, platelets 232, erythrocyte sedimentation rate 40, C-reactive protein 53 mg/dL, and mild derangement in liver function tests. Autoimmune workup was negative. Synovial fluid analysis showed a non-inflammatory effusion. A computed tomography (CT) scan of the abdomen revealed multiple small microabscesses. The patient was started on empirical antibiotics based on the suspicion of a liver abscess and symptomatic treatment for joint pain, but her symptoms did not improve. Magnetic resonance imaging (MRI) of the knee suggested joint effusion and osteomyelitis. Brucellosis was diagnosed based on antibodies and blood culture. She was started on standard treatment, her symptoms improved, and she was discharged with a six-week course of treatment. Our case highlights the diagnostic challenges of brucellosis, a zoonotic infection with diverse manifestations, in a young female presenting with fever, non-inflammatory knee effusion, osteomyelitis, and hepatic microabscesses. It underscores the importance of a thorough workup and cross-specialty collaboration, including rheumatology, infectious diseases, and radiology, to avoid misdiagnosis and ensure timely intervention.