The clinical syndrome described as severe, tender erythema with epidermal separation in an infant is most consistent with infection by which organism?

• A. Streptococcus pyogenes
• B. Staphylococcus aureus
• C. Bacillus anthracis
• D. Erysipelothrix rhusiopathiae

Answer: (B)

Severe, tender erythema with epidermal separation in an infant points to a toxin-mediated skin condition caused by Staphylococcus aureus, known as staphylococcal scalded skin syndrome (SSSS). The exfoliative toxins A and B produced by S. aureus circulate in the bloodstream and cleave desmoglein-1 in the superficial epidermis, causing loss of cell adhesion and sheets of desquamation just beneath the stratum granulosum. In infants, lack of circulating protective antibodies allows widespread toxin effect, leading the skin to peel easily and appear light red and tender. This pattern is distinct from infections caused by the other organisms listed, which produce different clinical pictures (for example, cutaneous anthrax with a painful eschar, erysipeloid from Erysipelothrix, or impetigo from Streptococcus without the widespread epidermal separation seen in SSSS).