Pneumonia USMLE Step 1 Practice Question
A 42-year-old male presents to the emergency department with a 5-day history of productive cough, fever, and acute right-sided pleuritic chest pain. He reports dyspnea on exertion. Vital signs show temperature 38.9°C, heart rate 102 bpm, blood pressure 128/76 mmHg, and respiratory rate 22/min. Physical examination reveals diminished breath sounds and dullness to percussion at the right lung base. Chest radiograph shows a large right-sided pleural effusion with right lower lobe consolidation. Pleural fluid obtained via thoracentesis has the following characteristics: pH 6.8, glucose 28 mg/dL, LDH 850 U/L, protein 4.2 g/dL, and positive gram stain with gram-positive cocci in clusters. Blood cultures are pending. Which of the following is the most likely diagnosis?
Answer choices
- AStreptococcus pneumoniae pneumonia with parapneumonic effusion progressing to empyemaCorrect answer
- BStaphylococcus aureus pneumonia with purulent pleural effusion
- CKlebsiella pneumoniae pneumonia with exudative pleural effusion
- DMycobacterium tuberculosis with tuberculous pleuritis
- EPneumococcal pneumonia with transudative pleural effusion
- FRheumatoid pneumoconiosis with secondary bacterial superinfection
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