Staphylococcal scalded skin syndrome

Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports

Open full size image

Staphylococcal scalded skin syndrome (SSSS) is a highly contagious, blistering condition triggered by exfoliative, toxin-producing Staphylococcus aureus, most commonly affecting neonates and children under the age of 6 years. It rarely presents in adults, although the incidence in adults appears to be increasing, usually in association with renal failure, immunocompromise, and possibly non-steroidal antiinflammatory drugs (NSAIDs). SSSS can develop after viral illnesses such as respiratory tract infections and varicella and after skin-penetrating procedures such as heel prick and vitamin K injections in neonates, intraarticular injections, and peritoneal dialysis.

The estimated incidence in Western countries ranges from 0.56 to 2.51 cases/year/million inhabitants with a reported seasonal peak in summer/autumn, although this link has been disputed. In healthy infants, mortality is uncommon, with reported rates up to 3%, contrasting with up to 50%–60% in adults with comorbidity. Death occurs due to complications such as pneumonia, hypovolemia, electrolyte imbalance, and sepsis.

SSSS is caused by hematogenous spread of exfoliative toxin (ET), mainly ET-A and/or B, produced by S. aureus, including methicillin-sensitive (MSSA), methicillin-resistant (MRSA), and multidrug resistant strains. Approximately 5% of all S. aureus produce ET. ET-producing MRSA strains appear more prevalent in Japan. ETs are serine proteases specifically cleaving desmosomal protein desmoglein-1, disrupting keratinocyte adhesion in the superficial epidermis. Increased susceptibility may reflect impaired renal clearance of ET in neonates and adults with renal failure or low titers of ET-specific antibodies in immunocompromised individuals.

Clinical features include a prodrome of malaise, irritability, and fever. Skin manifestations develop within 24 to 48 hours. Tender erythema is followed by superficial, flaccid blistering, most pronounced in flexural and periorificial areas, sparing mucosal surfaces, and ranging from localized blisters to widespread exfoliation. This leads to impaired thermoregulation and fluid balance and susceptibility to sepsis and secondary infection. The Nikolsky sign is positive. With successful treatment SSSS resolves over 10–14 days. Bullae rupture leaving denuded skin, followed by reepithelialization without scarring.

The causative organism cannot usually be cultured from affected skin because this is a circulating toxin-mediated process. The infection may be acquired by skin-to-skin contact from another individual with either a symptomatic infection or one who is an asymptomatic carrier. It may be possible to culture ET-producing S. aureus from extracutaneous sites, most commonly the nasopharynx, but also the rectum, conjunctiva, urinary tract, umbilicus, and blood. Polymerase chain reaction (PCR) or random amplified polymorphic DNA analysis may identify the toxin-encoding genes. Histology of affected skin typically shows a superficial subcorneal blister, absence of epidermal necrosis, and minimal inflammation. A frozen section of blister roof can confirm the superficial level of cleavage, facilitating a more rapid diagnosis.

The main differential diagnosis is the Stevens–Johnson syndrome–toxic epidermal necrolysis spectrum, in which distinguishing features include targetoid skin lesions, mucosal involvement, and subepidermal level of blistering with full-thickness epidermal necrosis. Additional differential diagnoses in infants include hereditary conditions such as epidermolysis bullosa, epidermolytic ichthyosis, and bullous mastocytosis.