A 10-year-old boy is brought to the emergency department by…
A 10-year-old boy is brought to the emergency department by his parents because he has had worsening cough, fever, and difficulty breathing over the past three days. The patient was evaluated by his pediatrician five days ago when the symptoms began and received a diagnosis of influenza B virus. Supportive care was recommended for treatment. Temperature is 39.4°C (103.0°F). The patient appears ill. Oxygen saturation is 86% on room air, and 2 L/min of oxygen via nasal cannula is administered. A chest x-ray study is shown. Which of the following is the most likely causal agent?