A healthy outpatient with suspected community-acquired pneumonia should be treated with which antibiotic?

• A. Amoxicillin
• B. Ceftriaxone
• C. Vancomycin
• D. Azithromycin

Answer: (D)

When treating a healthy outpatient with suspected community-acquired pneumonia, the goal is to cover both typical bacteria like Streptococcus pneumoniae and atypical organisms such as Mycoplasma and Chlamydophila, which commonly cause CAP in otherwise healthy adults. A macrolide like azithromycin provides good activity against S. pneumoniae and atypicals, and its pharmacokinetics allow convenient oral dosing and a short course, making it a practical first-line option for outpatient therapy in a patient with no comorbidities or risk factors for resistant organisms.

Amoxicillin alone targets the typical bacteria well but does not reliably cover atypicals, so it may miss important pathogens in this setting. Ceftriaxone is effective for CAP but is given by injection and is not suitable for outpatient treatment. Vancomycin targets resistant Gram-positive bacteria and is reserved for severe illness or specific MRSA concerns, not a routine outpatient CAP regimen.