What is first-line empiric therapy for outpatient CAP in a previously healthy adult without risk factors for drug resistance?

• A. Macrolide (azithromycin or clarithromycin) or doxycycline.
• B. Fluoroquinolone monotherapy.
• C. Amoxicillin-clavulanate alone.
• D. Cephalexin.

Answer: (A)

Treat outpatient CAP in a healthy adult with agents that cover both typical bacteria and atypical pathogens such as Mycoplasma and Chlamydophila. A macrolide (like azithromycin or clarithromycin) or doxycycline achieve this broad coverage with a favorable safety profile and good patient adherence, making them appropriate first-line choices in someone with no comorbidities or resistance risks.

Fluoroquinolone monotherapy is effective but reserved for cases with comorbidities or when first-line options aren’t suitable, due to concerns about side effects and antibiotic stewardship. Amoxicillin-clavulanate alone mainly targets typical bacteria and doesn’t reliably cover atypicals, so it’s not ideal as a sole first-line option in this scenario. Cephalexin lacks activity against atypical organisms, so it’s not appropriate as a first-line choice for CAP.