A neonate develops bullous skin lesions at 5 days of age. Nikolsky's sign is positive. The lesions are caused by an exfoliative toxin (ET) that cleaves desmoglein-1. The most likely causative organism is:
- A Staphylococcus aureus phage group II producing exfoliative toxin A/B ✓
- B Streptococcus pyogenes producing pyrogenic exotoxin A
- C Staphylococcus epidermidis producing delta-toxin
- D Corynebacterium diphtheriae producing diphtheria toxin
Correct answer: A. Staphylococcus aureus phage group II producing exfoliative toxin A/B
Explanation
Staphylococcal scalded skin syndrome (SSSS/Ritter's disease in neonates) is caused by Staphylococcus aureus phage group II (especially phage types 71 and 55) producing exfoliative toxin (ET-A or ET-B), a serine protease that cleaves desmoglein-1 within the granular layer of the epidermis. This causes intraepidermal cleavage and characteristic positive Nikolsky's sign. Treatment is anti-staphylococcal antibiotics (nafcillin or cloxacillin; vancomycin for MRSA).
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.