Pneumonia USMLE Step 1 Practice Question
A 67-year-old man on chronic prednisone for polymyalgia rheumatica presents with fever (38.9°C), productive cough with rust-colored sputum, and pleuritic chest pain. Vital signs show BP 128/82, HR 94, RR 22, SpO2 98% on room air. Chest X-ray demonstrates left lower lobe consolidation. Laboratory studies reveal WBC 13,200/μL. He denies recent antibiotic use. Which organism is most likely responsible for this pneumonia?
Answer choices
- ALegionella pneumophila
- BStaphylococcus aureus
- CNocardia asteroides
- DStreptococcus pneumoniaeCorrect answer
- EMycobacterium tuberculosis
- FKlebsiella pneumoniae
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.