For odontogenic infections in penicillin-allergic patients with anaerobic coverage, which antibiotic is often preferred?

• A. Amoxicillin
• B. Azithromycin
• C. Cephalexin
• D. Clindamycin

Answer: (D)

The key idea is choosing an antibiotic that reliably targets the anaerobic bacteria commonly involved in odontogenic infections and is safe for patients with penicillin allergy. Clindamycin fits this need well: it has strong activity against oral anaerobes and many streptococci, and it penetrates bone and inflamed soft tissue effectively, which helps resolve dental infections that sit in abscesses or bone. Because it’s not a beta-lactam, it avoids issues tied to penicillin allergy.

Amoxicillin would be a typical first choice for many infections, but it’s a penicillin family drug, so it’s generally avoided in penicillin-allergic patients. Azithromycin offers some coverage for oral pathogens but has more limited anaerobic activity, making it less reliable for odontogenic infections. Cephalexin is a cephalosporin with beta-lactam structure and potential cross-sensitivity with penicillins; its anaerobic coverage is also weaker. Thus, clindamycin provides the best combination of reliable anaerobic coverage and suitable tissue penetration in the penicillin-allergic patient with odontogenic infection.