An infant develops sudden onset of generalised blistering with a positive Nikolsky sign. S. aureus is isolated from a distant skin site (not the blisters). The toxin responsible acts by cleaving which skin protein?

• A Type IV collagen at the dermo-epidermal junction
• B Fibronectin in the deep dermis
• C Desmoglein-1 in the superficial granular layer of the epidermis ✓
• D Laminin-332 in the basement membrane

Explanation

Staphylococcal scalded skin syndrome (SSSS) is caused by exfoliative toxins (ET-A and ET-B) produced by phage group II S. aureus. These toxins are serine proteases that specifically cleave desmoglein-1, a desmosomal cadherin in the superficial granular layer of the epidermis, causing intraepidermal splitting and the characteristic superficial blistering. Sterile blister fluid distinguishes SSSS from bullous impetigo (local toxin production). Laminin-332 cleavage occurs in junctional epidermolysis bullosa.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.