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Community-Acquired Pneumonia — ABIM Board MCQ

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EasyRespiratory MedicineCommunity-Acquired PneumoniaABIM Board

A 45-year-old immunocompetent adult has fever, cough, and a new lobar consolidation on chest radiography. The patient is clinically stable and suitable for outpatient treatment. There are no chronic heart, lung, liver, or kidney diseases; diabetes mellitus; alcoholism; malignancy; asplenia; drug allergies; or risk factors for MRSA or Pseudomonas aeruginosa. Local pneumococcal resistance to macrolides is at least 25%. Which empiric antibiotic regimen is most appropriate?

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Correct answer: D — Amoxicillin 1,000 mg orally three times daily

The correct answer is D. For an otherwise healthy outpatient with community-acquired pneumonia and no risk factors for resistant pathogens, ATS/IDSA guidance recommends amoxicillin 1 g orally three times daily or doxycycline. Amoxicillin is therefore the listed first-line regimen. Azithromycin monotherapy is acceptable only where local pneumococcal macrolide resistance is below 25%, which is explicitly excluded here. Levofloxacin monotherapy and amoxicillin-clavulanate plus doxycycline are broader regimens recommended for outpatients with specified comorbidities. Ceftriaxone plus azithromycin is a parenteral regimen used for hospitalized patients with nonsevere CAP, not a clinically stable outpatient.

Reference: Metlay JP, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia: An Official ATS/IDSA Clinical Practice Guideline, Question 8 and Table 3. 2019. https://www.idsociety.org/globalassets/idsa/practice-guidelines/community-acquired-pneumonia-in-adults/executive_summary.pdf