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Community-Acquired Pneumonia (Comorbid) — ABIM Board MCQ

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ModerateInfectious DiseasesCommunity-Acquired Pneumonia (Comorbid)ABIM Board

A 67-year-old diabetic man with chronic kidney disease presents with suspected aspiration pneumonia from community-acquired setting. He has been stabilized on broad-spectrum inpatient antibiotics and is now ready for transition to outpatient therapy. According to current US guidelines for comorbid outpatients with CAP, which regimen is the most appropriate choice?

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Correct answer: A — Amoxicillin‑clavulanate plus doxycycline

In outpatient adults with comorbidities (e.g., diabetes, CKD), IDSA/ATS 2019 recommends either amoxicillin‑clavulanate (or a cephalosporin) combined with a macrolide or doxycycline, or monotherapy with a respiratory fluoroquinolone. Amoxicillin‑clavulanate plus doxycycline follows this evidence‑based combination approach. Azithromycin alone and ceftriaxone alone are monotherapies inappropriate for comorbid patients. Linezolid is reserved for MRSA—not routine CAP. Piperacillin‑tazobactam is overly broad and not recommended in outpatient CAP management.

Reference: IDSA/ATS Clinical Practice Guideline, Diagnosis and Treatment of Adults with Community‑Acquired Pneumonia (2019), Table 3; StatPearls summary (2024). https://www.ncbi.nlm.nih.gov/books/NBK470459/