A patient is diagnosed with secondary syphilis. During treatment with benzathine penicillin, he develops fever, rigors, hypotension, and worsening rash within 4 hours. The mechanism of this reaction is:
- A Jarisch-Herxheimer reaction — massive release of treponemal lipoproteins triggering TNF-α and IL-6 ✓
- B Penicillin allergy — IgE-mediated anaphylaxis
- C Serum sickness — immune complex deposition from penicillin-protein conjugates
- D Nitroid crisis — vasovagal response to intramuscular injection
Correct answer: A. Jarisch-Herxheimer reaction — massive release of treponemal lipoproteins triggering TNF-α and IL-6
Explanation
The Jarisch-Herxheimer reaction occurs within 2-8 hours of initiating antibiotic therapy in syphilis (most common in secondary syphilis), caused by rapid release of treponemal lipoproteins and heat shock proteins, stimulating monocytes and macrophages to release TNF-α, IL-6, and IL-8. It is not an allergic reaction — the drug should be continued. Management is antipyretics and supportive care. It is most dangerous in neurosyphilis and syphilis in pregnancy.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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