An 82-year-old man with COPD and presumed pneumonia who has a penicillin allergy; which antibiotic is most appropriate?

• A. Doxycycline
• B. Amoxicillin
• C. Cefuroxime
• D. Clarithromycin

Answer: (D)

In pneumonia, especially in an older patient with COPD, you want an antibiotic that covers both typical bacteria (like Streptococcus pneumoniae and Haemophilus influenzae) and atypical pathogens (such as Mycoplasma, Chlamydophila, and Legionella), while avoiding beta-lactams if there is a penicillin allergy. A macrolide fits this need well because it has reliable activity against typical respiratory pathogens and excellent activity against atypicals, including Legionella, which is a consideration in COPD patients.

Clarithromycin, a macrolide, provides broad coverage appropriate for outpatient management in someone with a penicillin allergy. It also has convenient oral dosing and doesn’t rely on a beta-lactam, reducing risk if the patient has a true penicillin reaction.

Doxycycline could be considered as an alternative for mild cases, since it covers many of the same organisms, but macrolides generally offer more robust coverage for Legionella and common COPD-associated pathogens. Amoxicillin is not suitable due to the penicillin allergy, and cefuroxime (a cephalosporin) carries cross-reactivity concerns in penicillin-allergic patients and has less reliable coverage of atypicals.