In penicillin-allergic patients with streptococcal pharyngitis, which antibiotic is an acceptable alternative?

• A. Azithromycin
• B. Erythromycin
• C. Clindamycin
• D. Doxycycline

Answer: (B)

When penicillin can’t be used because of an allergy, you still need reliable activity against group A Streptococcus to treat streptococcal pharyngitis. Erythromycin fits that role because it’s a macrolide with proven activity against Streptococcus pyogenes and has long been used as a non–beta-lactam alternative in penicillin-allergic patients. It reaches the pharyngeal tissues well and allows effective treatment without a beta-lactam.

Other options have drawbacks in some patients or settings: doxycycline is avoided in children and pregnant patients; clindamycin is effective but carries a higher risk of C. difficile infection; azithromycin is also used but local GAS resistance patterns can limit its effectiveness. Given these factors, erythromycin is a classic, acceptable substitute for penicillin in this scenario.