Two hours after receiving intramuscular benzathine penicillin for early syphilis, a patient develops rigors, fever, hypotension, and worsening of malaise. This reaction is attributed to:

• A IgE-mediated type I hypersensitivity to penicillin
• B Direct toxic effect of penicillin on the myocardium
• C Immune complex deposition in small vessels
• D Release of treponemal lipoproteins triggering cytokine release ✓

Explanation

This is the Jarisch-Herxheimer reaction, an acute febrile reaction occurring within hours of starting effective antimicrobial therapy in spirochaetal infections such as syphilis, leptospirosis, and relapsing fever. Massive killing of organisms releases lipoproteins and endotoxin-like substances that provoke a surge of TNF-alpha, IL-6, and IL-8, producing fever, rigors, hypotension, and exacerbation of symptoms. It is self-limiting and managed supportively, and it is not an allergic reaction to the antibiotic.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.