In community-acquired pneumonia without comorbidities, which class of antibiotic is typically used as first-line outpatient therapy?

• A. Amoxicillin-clavulanate
• B. Cephalexin
• C. Macrolide
• D. Doxycycline

Answer: (C)

Macrolides are a common first-line choice for healthy outpatients with community-acquired pneumonia because they cover the usual bacteria that cause CAP and, importantly, the atypical pathogens (like Mycoplasma and Chlamydophila) that frequently appear in ambulatory cases. They act by inhibiting bacterial protein synthesis, and agents such as azithromycin have excellent respiratory penetration and convenient dosing, which helps with adherence and completion of therapy. Amoxicillin-clavulanate, while effective against many typical bacteria, doesn’t reliably cover atypicals and is more often reserved for patients with comorbidities or higher risk for resistant organisms. Cephalexin mainly targets typical bacteria and misses atypicals, making it a poorer choice for CAP. Doxycycline is a solid alternative, especially when macrolide use is limited, but the classic first-line option in healthy outpatients remains a macrolide due to its broad coverage and tolerability.