A typical first-line therapy for CAP due to Streptococcus pneumoniae is amoxicillin. Which option correctly reflects this choice?

• A. Azithromycin
• B. Amoxicillin
• C. Ciprofloxacin
• D. Doxycycline

Answer: (B)

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia in adults, so the first-line choice should be an agent that reliably kills pneumococcus and is practical for outpatient use. Amoxicillin fits this best: it has strong activity against Streptococcus pneumoniae, including penicillin-susceptible strains, and its oral bioavailability is excellent, allowing effective high-dose outpatient therapy. Using a higher dose helps ensure adequate drug levels in the airways and reduces the chance of treatment failure from low‑level resistance. It’s also cost-effective and well tolerated, making it a straightforward and reliable initial option for typical CAP caused by pneumococcus.

Other antibiotics can be used in certain situations—for example, azithromycin may be chosen when penicillin allergy or regional resistance patterns push toward a macrolide, but rising macrolide resistance can reduce efficacy. Ciprofloxacin isn’t ideal for CAP because its pneumococcal activity is less reliable and it carries broader safety concerns. Doxycycline can be an alternative in some cases, but its effectiveness can be more variable depending on local resistance patterns.