COPD USMLE Step 1 Practice Question
A 2-year-old boy presents with fever (38.5°C), hoarse voice, and barking cough worse at night with inspiratory stridor. Vital signs show HR 115/min, RR 28/min, SpO2 98% on room air. Neck X-ray reveals characteristic subglottic narrowing with the "steeple sign." He denies dysphagia and has no drooling. He takes no regular medications. Which pathogen most likely causes this condition?
Answer choices
- AStreptococcus pneumoniae
- BParainfluenza virusCorrect answer
- CHaemophilus influenzae type b
- DCoronavirus
- ERespiratory syncytial virus
- FRhinovirus
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