Review Question - QID 107976

A young Mediterranean teen brings her 4-year-old little brother to the Emergency Room because of a high temperature. Their parents are on their way to the hospital, but, in the meantime, she provides some of the history. She explains that he has been running a fever and limping for the past week. This morning, she had trouble awakening him, and she noticed some swelling and redness around his right ankle. In terms of his past medical history, she knows he has something wrong with his blood. He had to receive extra vaccinations as an infant, and he takes an antibiotic everyday. On exam in the ED, his temperature is 102.4 deg F (39.1 deg C), blood pressure is 90/60 mmHg, pulse is 123/min, and respirations are 22/min. He is lethargic, and his exam is noteworthy for erythema and edema in an area surrounding his distal shin. What is the most likely diagnosis?