A 4-day-old neonate in the NICU develops scalded skin syndrome (SSSS). Blood culture is negative. Which virulence factor is responsible and from where is the responsible organism likely colonised?
- A Alpha toxin produced by S. aureus at the site of infection causing direct epidermal necrosis
- B Exfoliatin (ET-A/ET-B) produced by S. aureus at a remote site, cleaving desmoglein 1 in the superficial epidermis ✓
- C Toxic shock syndrome toxin-1 (TSST-1) acting as a superantigen
- D Leukocidin (PVL) disrupting neutrophil membranes systemically
Correct answer: B. Exfoliatin (ET-A/ET-B) produced by S. aureus at a remote site, cleaving desmoglein 1 in the superficial epidermis
Explanation
Staphylococcal scalded skin syndrome (SSSS/Ritter disease in neonates) is caused by exfoliative toxins ET-A and ET-B, serine proteases that specifically cleave desmoglein 1 in the superficial epidermis. Crucially, the primary infection (umbilicus, conjunctiva, or nasopharynx) is remote from the skin lesions; the toxins are haematogenously distributed, explaining the negative blood culture and sterile blister fluid. TSST-1 causes toxic shock syndrome (fever, hypotension, rash) without bullae. Alpha toxin causes local tissue necrosis.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.