system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A previously healthy 5-year-old boy is brought to the physician because of a 2-day history of itchy rash and swelling on his left lower leg. His mother says the boy complained of an insect bite while playing outdoors 3 days before the onset of the lesion. His immunizations are up-to-date. He is at the 50th percentile for height and the 85th percentile for weight. He has no known allergies. His temperature is 38.5°C (101.3°F), pulse is 120/min, and blood pressure is 95/60 mm Hg. The lower left leg is swollen and tender with erythema that has sharply defined borders. There is also a narrow red line with a raised border that extends from the lower leg to the groin. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of these findings?
assistant
Streptococcus pyogenes infection
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