Which single-agent regimen is acceptable for CAP in patients with significant comorbidities?

• A. Amoxicillin-clavulanate plus macrolide
• B. Levofloxacin monotherapy
• C. Amoxicillin alone
• D. Doxycycline alone

Answer: (B)

In CAP for patients with significant comorbidities, you want a single agent that can cover both typical bacteria and atypical pathogens. Levofloxacin has broad activity against Streptococcus pneumoniae (including penicillin-resistant strains), Haemophilus influenzae, Moraxella, and atypicals such as Mycoplasma, Chlamydophila, and Legionella, so it provides comprehensive coverage without needing a second drug. Amoxicillin alone misses atypicals, and amoxicillin-clavulanate plus a macrolide involves two agents; doxycycline alone may be less reliable against resistant pneumococcus and isn’t the preferred sole therapy in more ill patients.