A neonate develops widespread superficial blistering and exfoliation of skin in large sheets. The causative Staphylococcus aureus strain is most commonly from phage group II. The toxin responsible acts by:
- A Cleaving SNARE proteins at neuromuscular junctions
- B Cleaving desmoglein-1 in the granular layer of the epidermis ✓
- C ADP-ribosylation of elongation factor-2
- D Activation of T-cell superantigen pathway causing massive cytokine release
Correct answer: B. Cleaving desmoglein-1 in the granular layer of the epidermis
Explanation
Staphylococcal scalded skin syndrome (SSSS) is caused by exfoliative (epidermolytic) toxins A and B, serine proteases produced by S. aureus phage group II strains. These toxins specifically cleave desmoglein-1, the desmosomal cadherin in the granular layer of the epidermis, disrupting cell-cell adhesion and causing superficial intraepidermal cleavage. Unlike toxic epidermal necrolysis (TEN), the split is at the granular layer without keratinocyte necrosis, and the Nikolsky sign is positive. TSST-1 (option D) causes toxic shock syndrome.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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