Staphylococcal scalded skin syndrome: SAQ

This infant presents the classic constellation of generalised staphylococcal scalded skin syndrome: a prodrome of irritability and fever, scarlet erythema around the mouth and flexures, flaccid bullae, and sheet-like peeling with a positive Nikolsky sign. The sparing of the oral, conjunctival, and genital mucosae is the single feature that separates this from Stevens-Johnson syndrome and toxic epidermal necrolysis, and it should be documented explicitly. This is a toxin-mediated disease in which the source is remote, the skin heals without scarring, and anti-staphylococcal antibiotics switch off the toxin. [2]

Question 1 (10 marks)

Outline the pathophysiology of this condition, and explain why the mucous membranes are spared. [1]

The disease is produced by phage-group-II Staphylococcus aureus that colonises a distant focus such as the conjunctiva, the umbilicus, the nasopharynx, or the nappy area. The organism secretes exfoliative toxin A, which is chromosomally encoded and heat-stable, and exfoliative toxin B, which is plasmid-encoded and heat-labile. These toxins are serine proteases with a precise specificity for desmoglein 1, the desmosomal adhesion molecule that binds superficial keratinocytes. [1]

The toxin travels in the blood to the skin, where it cleaves desmoglein 1 in the stratum granulosum, dissolving the glue between the outermost keratinocytes. The split is therefore superficial, which is why the skin peels like a scald but heals without scarring, and why the Nikolsky sign is positive. Infants clear the toxin slowly through immature kidneys, which is why the disease is overwhelmingly one of the very young. [2]

The mucous membranes are spared because desmoglein 3, which the toxin does not cleave, takes over the adhesion role in the oral, conjunctival, and genital surfaces. This single molecular fact is the cardinal clue against Stevens-Johnson syndrome and toxic epidermal necrolysis, in which the mucosae are involved and the split is full-thickness. Documenting the intact mucosae at every assessment keeps this distinction clear. [2]

Question 2 (10 marks)

Describe your initial management including resuscitation, antibiotic choice, and supportive care. [3]

Begin with attention to fluid, temperature, and pain, because the child with extensive skin loss behaves like a burn patient. Assess the airway and breathing, establish intravenous access, and estimate the extent of skin involvement as a percentage of body surface area, because fluid losses scale with that figure. Give analgesia before any handling of the raw skin, and correct dehydration and electrolyte losses with intravenous fluids calculated to cover maintenance plus insensible loss. Maintain the child in a neutral thermal environment, because the loss of the skin barrier promotes heat loss. [3]

Give the first dose of anti-staphylococcal antibiotic immediately after cultures and focus swabs are drawn, because halting toxin production is the definitive act of therapy. Intravenous flucloxacillin or cefazolin is first-line, and adding clindamycin is rational because it suppresses toxin synthesis through its effect on ribosomal protein production. Switch to vancomycin if methicillin-resistant Staphylococcus aureus is suspected or prevalent locally. The diagnosis is clinical and the antibiotic should be on board within minutes of the decision to treat. [3]

Supportive skin care is the other half of management and matters as much as the antibiotic. Apply emollients and non-adherent dressings to the raw areas, handle the child gently to avoid extending the shearing, and use a barrier cream to protect the healing skin. Steroids are not indicated and topical antibiotics have little role, because the focus is systemic. Swab the suspected focus, such as the conjunctiva or the nasopharynx, to identify the source, and counsel the family that the skin will heal completely without scarring within one to two weeks. [2]