A neonate develops extensive superficial bullous skin lesions that rupture easily, leaving moist raw areas. The mother had a Staphylococcus aureus skin infection. Which toxin is responsible, and what is its molecular target in the skin?
- A TSST-1 targeting the VMβ2 region of T-cell receptor
- B Alpha-toxin forming pores in keratinocyte membranes
- C Exfoliative toxin A/B (ETA/ETB) specifically cleaving desmoglein-1 in the stratum granulosum ✓
- D Panton-Valentine leukocidin (PVL) causing leucocyte lysis in the dermis
Correct answer: C. Exfoliative toxin A/B (ETA/ETB) specifically cleaving desmoglein-1 in the stratum granulosum
Explanation
Staphylococcal scalded skin syndrome (SSSS) is caused by exfoliative toxins A and B (serine proteases encoded by chromosomal eta and plasmid-borne etb genes respectively). They specifically cleave desmoglein-1, a cadherin in the desmosomes of the stratum granulosum, causing superficial intraepidermal cleavage without bacteria at the blister site. This explains the Nikolsky sign. TSST-1 is a superantigen causing toxic shock syndrome. Alpha-toxin causes deeper tissue destruction. PVL causes furuncles and necrotising pneumonia.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.