A 28-year-old man with secondary syphilis receives intramuscular benzathine penicillin G. Two hours later he develops high fever with rigors, hypotension, and intensification of his rash. He stabilises with supportive care over the next 12 hours. What is the underlying mechanism of this reaction?
- A IgE-mediated mast cell degranulation triggered by penicilloyl hapten
- B Release of tumour necrosis factor and interleukins following massive killing of treponemes ✓
- C Immune complex deposition in small vessels of the skin
- D Direct toxic effect of penicillin on the hypothalamic thermoregulatory centre
Correct answer: B. Release of tumour necrosis factor and interleukins following massive killing of treponemes
Explanation
The Jarisch-Herxheimer reaction is a systemic inflammatory response occurring 1 to 2 hours after initiation of therapy for syphilis, especially secondary syphilis. Mass death of treponemes releases lipoproteins that trigger a brisk cytokine cascade dominated by tumour necrosis factor alpha, interleukin-6, and interleukin-8, producing fever, rigors, hypotension, and worsening of lesions. It is self-limiting and managed supportively. It is not an allergic reaction to penicillin, so treatment should not be stopped.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.