A 70-year-old man with fever and an acutely swollen, tender right knee joint with reduced range of motion presents to the emergency department. He has a prosthetic hip but no prosthesis in the knee. What is the most appropriate next step?AStart oral NSAIDs and review in 48 hoursBArrange urgent joint aspiration for gram stain and culture, and commence intravenous antibioticsCOrder MRI only and wait for the report before treatmentDInject intra-articular corticosteroids immediatelyEReassure and dischargeCheck my answer