Toxin-mediated skin disease: Which specific Staphylococcus aureus toxin is responsible for the scalded skin syndrome (Ritter disease) characterized by widespread epidermal peeling?

Introduction / Context:
Staphylococcal scalded skin syndrome (SSSS) is a toxin-mediated illness predominantly affecting infants and young children. Identifying the responsible toxin aids in understanding disease pathophysiology and in distinguishing it from toxin-independent skin infections.

Given Data / Assumptions:

• Clinical picture: tender erythema with superficial epidermal splitting and desquamation.
• Causative agent: toxigenic S. aureus strains.
• Toxin targets desmosomal proteins in the superficial epidermis.

Concept / Approach:
Epidermolytic (exfoliative) toxins ETA and ETB are serine proteases that cleave desmoglein 1, disrupting keratinocyte cell–cell adhesion in the stratum granulosum. Enterotoxins cause food poisoning; leukocidins target leukocytes; hemolysins lyse red cells. Therefore, the toxin producing the scalded skin phenotype is the epidermolytic toxin.

Step-by-Step Solution:
Associate SSSS with toxin-mediated epidermal cleavage. Recall that exfoliative toxins specifically cleave desmoglein 1. Exclude enterotoxin (GI symptoms), leucocidin (WBC lysis), hemolysin (RBC lysis). Select “Epidermolytic toxin.”

Verification / Alternative check:
Histology shows a cleavage plane within the superficial epidermis without abundant bacteria, consistent with a circulating toxin rather than direct tissue invasion.

Why Other Options Are Wrong:

• Enterotoxin: emesis and diarrhea from food poisoning, not epidermal peeling.
• Leucocidin: neutrophil lysis (e.g., PVL) leading to pus and necrosis, not SSSS.
• Haemolysin: erythrocyte lysis; not the cause of SSSS.

Common Pitfalls:
Confusing toxic shock syndrome (superantigen-mediated) with SSSS; different toxins and clinical pictures.

Final Answer:
Epidermolytic toxin