A 17-year-old presents with marked exudative tonsillitis, cervical lymphadenopathy, hepatosplenomegaly, and fever unresponsive to a week of oral penicillin. Peripheral smear shows atypical lymphocytes. The most likely causative agent is:
- A Epstein-Barr virus ✓
- B Group A beta-haemolytic Streptococcus
- C Adenovirus
- D Fusobacterium necrophorum
Correct answer: A. Epstein-Barr virus
Explanation
Exudative tonsillitis with splenomegaly, generalised lymphadenopathy, atypical lymphocytes, and failure to respond to penicillin is classic infectious mononucleosis caused by EBV. Heterophile antibodies (Paul-Bunnell test) support the diagnosis. B useful exam pearl: giving ampicillin or amoxicillin in these patients causes a maculopapular rash in the majority. Group B streptococcus would not cause splenomegaly or atypical lymphocytes, killing that distractor.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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