Staphylococcal Scalded Skin Syndrome in a Healthy Adult

Severe bacterial infections of the skin: uncommon presentations

Although most bacterial infections of the skin prove to be minor in nature, a few such dermatologic entities are significant, to the point of even being fatal. Their course can be extremely rapid and can lead to dreadful complications. The mortality rate is usually up to 30% to 50% and depends upon the type of infection, underlying disease, and immune status. Patients suffering them usually need to be hospitalized, sometimes in intensive care or burn units. They should be treated systemically with appropriate antimicrobial therapy plus aggressive supportive care. The two life-threatening skin infections which are most commonly experienced are toxin-mediated staphylococcal and streptococcal disorders; one could overlap the other. Several other related entities will also be discussed.

Treatment of staphylococcal scalded skin syndrome

Humans are a natural reservoir for Staphylococcal aureus. Colonization begins soon after birth and predisposes to infection. S. aureus is one of the most common causes of skin infection, giving rise to folliculitis, furunculosis, carbuncles, ecthyma, impetigo, cellulitis and abscesses. In addition, S. aureus may cause a number of toxin-mediated life-threatening diseases, including staphylococcal scalded skin syndrome (SSSS). Epidermolytic toxins released by certain S. aureus strains cause SSSS by cleaving the epidermal cell adhesion molecule, desmogelin-1, resulting in superficial skin erosion. Recent experiments have revealed similarities in the pathophysiology of SSSS and pemphigus foliaceus, an autoimmune disorder that is characterized by antibodies targeting the same epidermal attachment protein. SSSS typically affects neonates and infants but may also occur in predisposed adults. It is painful and distressing for the patient and parents, although most cases respond to antibiotic treatment. Mortality is low in infants but can be as high as 67% in adults, and is dependent on the extent of skin involvement and the comorbid state. Thus, the management of adults who develop SSSS remains a major therapeutic challenge. The antibody response against the toxins neutralizes their effect and prevents recurrence or limits the effects to the area of infection, which is known as bullous impetigo.

Staphylococcal epidermolysins

PURPOSE OF REVIEW

Staphylococcal epidermolysins are the major causative toxins of bullous impetigo and staphylococcal scalded skin syndrome. This disease is characterized by the splitting of the epidermis between two cell layers resulting in exfoliation. It predominantly affects newborn babies and exposes them to secondary infections. This leads to the risk of epidemics, especially in nurseries. With only an experimental model which consists of skin injections in newborn mice and the recent determination of three-dimensional structures, the essential function of these toxins remained controversial, split between that of specific proteases and that of superantigens.

RECENT FINDINGS

Staphylococcal epidermolysins now constitute a family of toxins, with the recent characterizations of two new serotypes: ETC and ETD. They may be secreted by sensitive or methicillin-resistant strains. Four molecules were also identified in Staphylococcus hyicus responsible for exudative epidermitis in swine. While different observations suggested a proteolytic action to these toxins, the histological parallel made with pemphigus foliaceus greatly helped in the characterization of the targets for epidermolysins ETA, ETB, ETD: desmoglein-1, a desmosome-constitutive protein, and incidentally melanocyte-stimulating hormones, which accounts for the blisters observed clinically.

SUMMARY

The growing complexity in staphylococcal toxins has to be taken into account both for their association with diseases and for diagnosis purposes. Even though cases of staphylococcal scalded skin syndrome in adults are rare, they raise further questions about the pathogenic features of the disease such as individual sensitivity and distribution of the toxins into the body.

Staphylococcal scalded-skin syndrome in an adult due to methicillin-resistant Staphylococcus aureus

We report a case of a 71-year-old man with staphylococcal scalded-skin syndrome (SSSS). The patient, with a chronic history of diabetes mellitus, was admitted to our hospital with lumbago, and a diagnosis of renal-cell carcinoma with bone metastasis was made. In hospital he had sudden onset of high fever and erythema, followed by the formation of flaccid bullae and exfoliation, with a positive Nikolsky sign. Methicillin-resistant Staphylococcus aureus (MRSA), producing exfoliative toxin B, was isolated from blood and bile cultures, and Aeromonas hydrophila was isolated from bile culture. Skin biopsy specimen showed a cleavage of the epidermis at the level of the granular layer. The patient was diagnosed as having SSSS and cholecystitis, and was treated with intravenous antibiotics and percutaneous transhepatic gallbladder drainage, which led to recovery. SSSS in adults is usually associated with immunosuppression. A. hydrophila is recognized as an opportunistic pathogen. SSSS should be considered in the differential diagnosis of immunocompromised adult patients with sudden onset of high fever and erythema.