For community-acquired pneumonia in a previously healthy adult, which antibiotic can be used as a single agent?

Prepare for the Adult-Gerontology Acute Care Nurse Practitioner Test. Study with interactive quizzes and detailed explanations. Boost your exam readiness with our diverse question formats and in-depth content coverage.

The key idea here is choosing a single antibiotic that covers both the common bacteria that cause pneumonia in healthy outpatients (like Streptococcus pneumoniae) and the atypical pathogens (such as Mycoplasma and Chlamydophila species) that frequently present with CAP. Azithromycin fits that need well. It is a macrolide with reliable activity against pneumococcus and atypicals, and it also offers convenient once-daily dosing over a short course, which improves adherence in the outpatient setting. Its pharmacokinetic profile provides good lung tissue penetration, making it an effective single-agent option for previously healthy adults with CAP.

Amoxicillin, while effective against typical pathogens, does not reliably cover atypicals, so it isn’t sufficient as the sole agent in this context. Clarithromycin has a similar spectrum to azithromycin, but azithromycin is often preferred due to simpler dosing and tolerability. Doxycycline can cover atypicals and some pneumococcus, but resistance considerations and guideline preferences often make azithromycin the more consistently recommended single-agent choice in this scenario. Therefore, azithromycin stands out as the best single-agent option for outpatient CAP in a previously healthy adult.