Two hours after receiving intramuscular benzathine penicillin for secondary syphilis, a 27-year-old man develops rigors, fever of 39.5 degrees Celsius, tachycardia and worsening of his rash. Blood pressure is 88/56 mmHg. The underlying mechanism of this reaction is:
- A Release of treponemal lipoproteins triggering tumour necrosis factor alpha and interleukins ✓
- B Deposition of circulating immune complexes in the skin
- C IgE-mediated anaphylaxis to penicillin
- D Direct dose-related toxicity of benzathine penicillin on vascular smooth muscle
Correct answer: A. Release of treponemal lipoproteins triggering tumour necrosis factor alpha and interleukins
Explanation
The Jarisch-Herxheimer reaction is an acute febrile reaction occurring within hours of starting effective therapy for syphilis, and also seen in leptospirosis and relapsing fever. Mass killing of spirochaetes releases endotoxin-like lipoproteins that provoke a surge of tumour necrosis factor alpha, interleukin-6 and interleukin-8, producing fever, rigors, hypotension and flare of lesions. It is self-limiting and managed supportively with antipyretics and fluids. It is not allergic, so penicillin need 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.