Pneumonia USMLE Step 1 Practice Question
A 23-year-old man presents with a 5-day history of low-grade fever, dry cough, and malaise. Vital signs show temperature 38.2°C, heart rate 92 bpm, respiratory rate 18/min, blood pressure 118/76 mmHg, and oxygen saturation 96% on room air. Chest radiograph demonstrates diffuse patchy interstitial infiltrates. Physical examination reveals only scattered end-inspiratory crackles; consolidation is absent. Leukocyte count is normal. He denies dyspnea. Which organism best explains this clinical and radiographic pattern?
Answer choices
- AStaphylococcus aureus pneumonia
- BAspiration pneumonia due to anaerobes
- CKlebsiella pneumoniae
- DMycoplasma pneumoniaeCorrect answer
- EStreptococcus pneumoniae
- FLegionella pneumophila
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