The Jarisch-Herxheimer reaction (a hypersensitivity reaction to antibiotic treatment of an infection) is most classically associated with treatment of which infection?

Correct answer: B. Syphilis

• A. INCORRECT — Candidiasis is a fungal infection, and antifungal therapy is not associated with Jarisch-Herxheimer reactions.
• B. CORRECT — The Jarisch-Herxheimer reaction occurs within hours of initiating antibiotic therapy for syphilis (Treponema pallidum), caused by the release of bacterial endotoxins/lipoproteins as spirochetes are killed. It presents as fever, chills, headache, and worsening lesions. Also seen in Lyme disease.
• C. INCORRECT — TB is not a spirochetal infection and does not classically cause Jarisch-Herxheimer reactions.
• D. INCORRECT — While Herxheimer reactions can rarely occur with other spirochetal infections, they are NOT classically associated with gonorrhea.