Intact skin serves as an effective mechanical barrier in the vast majority of healthy infants and children. Constant desquamation continually removes potentially invasive bacteria; however, almost any microorganism can live upon human skin under appropriate conditions.¹ It is helpful to view these in the framework of transient, resident, and pathogenic flora. Transient flora are microorganisms deposited on the skin from the environment, typically non-proliferative and easily removed by washing the affected region. Resident flora are a select group of organisms regularly found on the skin of normal individuals in appreciable numbers that form stably reproducing colonies and that are not easily dislodged. The resident flora consists primarily of gram-positive species such as Propionibacterium acnes, aerobic diphtheroids, and Staphylococcus epidermidis. A few gram-negative species such as Escherichia, Enterobacter, Proteus, and Pseudomonas are found uncommonly on normal skin, more likely being found in moist intertriginous regions such as the groin and toe webs.¹ Pathogenic organisms are not ordinarily found as part of the resident flora but may persist via continuous replacement from either an internal or external nidus of infection and include a wide range of organisms, most commonly, Staphylococcus aureus and group A β-hemolytic Streptococcus (GABHS).

BACKGROUND

Staphylococcal scalded skin syndrome (SSSS), alternatively known as Ritter’s disease or Pemphigus neonatorum, is a toxin-mediated exfoliative dermatitis caused by toxigenic strains of S. aureus, characterized by skin tenderness, flaccid bullae, and eventual skin sloughing. The disease occurs most commonly in children with slight male predominance; 98% being younger than the age of 6 years, 62% under the age of 2 years, and with neonates being especially susceptible.² SSSS can lead to serious complications such as pneumonia, hypothermia, dehydration, and secondary infections, particularly in newborns and immunocompromised adults in whom these complications can be lethal.²

PATHOPHYSIOLOGY

SSSS generally begins with colonization of the conjunctivae, naris, perioral region, perineum, or umbilicus by specific strains of S. aureus capable of producing the exfoliative toxins A (ETA) or B (ETB).¹ These usually belong to phage group II, with strains 71 and 55 being the most common. ETA accounts for an estimated 89% of cases.² Both exfoliative toxins cause intraepidermal splitting at the zona granulosa by destroying the protein desmoglein 1 which is an important component of the desmosome involved in keratinocyte intercellular adhesion and is the same protein targeted in the autoimmune blistering disease Pemphigus foliaceus.² This leads to fragile, flaccid bullae and eventual detachment of the superficial epidermis. The exfoliative toxins, unlike the toxin involved in staphylococcal toxic shock syndrome, are not known to produce direct hemodynamic compromise.² Neonates are thought to be particularly vulnerable to SSSS due to their immature immunity and decreased renal excretion of the toxin.

CLINICAL PRESENTATION

A local skin infection may be the first sign of SSSS, such as a purulent circumcision site or umbilical stump or rarely as a complication of measles or varicella; however, the source of infection is often not obvious.² A prodrome of fever, irritability, and coryza is common, especially in neonates and young children. There follows an incubation period of 1 to 10 days between skin infection and the appearance of diffuse tender, blanchable erythroderma usually beginning around the mouth. Flaccid, thin-walled bullae then appear within 1 to 2 days of the erythroderma, with positive Nikolsky sign in which lateral pressure of perilesional skin causes further extension of the bullae.² The bullae typically rupture within hours, followed by sloughing of the superficial epidermis in large sheets (Figure 106-1). Conjunctivitis and perioral radial fissures may also be present; however, other mucus membranes are spared (Figure 106-2). Within 1 to 3 days of the initial skin detachment, a second flaky desquamation of the denuded skin occurs.¹ The dermis is not typically involved and scarring is not expected as the skin gradually heals over the following 1 to 2 weeks.³

DIFFERENTIAL DIAGNOSIS

The main differential diagnosis to consider for SSSS is toxic epidermal necrolysis (TEN), a severe exfoliative dermatitis that is usually drug induced and has a high mortality rate.² However, besides the conjunctiva, mucosal membranes are typically spared in SSSS which helps to distinguish it from TEN. Other diagnoses to consider are Stevens-Johnson syndrome, scarlet fever, bullous impetigo, Kawasaki disease, burn injury, boric acid poisoning, epidermolysis bullosa, Pemphigus foliaceus, graft-versus-host disease, epidermolytic (bullous) ichthyosis, erythrodermic psoriasis, Methylmalonic acidemia, and familial peeling skin syndrome.^1,2

DIAGNOSTIC EVALUATION

The diagnosis of SSSS can often be made on clinical presentation alone. However, given the general prevalence of methicillin-resistant S. aureus (MRSA); blood, urine, wound cultures and swabs of the nasopharynx, eyes, axillae, groin, and any other suspected foci of infection should be obtained while antibiotics are readied.^2,3 Of note, the fluid within intact bullae is generally sterile as the responsible toxin is hematogenously spread. Swabs should be directed toward more typical areas of carriage or sites that appear purulent. If the diagnosis is in question, particularly if TEN cannot be excluded, microscopic examination can be performed on a skin snip from a blister roof or a skin biopsy, with SSSS demonstrating cleavage at the level of the granular epidermis and TEN usually below the dermal-epidermal junction.²

MANAGEMENT

Immediately following culture, essential treatment entails prompt initiation of a penicillinase-resistant penicillin such as nafcillin or oxacillin. Vancomycin or linezolid should be considered in areas with a high prevalence of community-acquired MRSA or in those who have failed to respond to the above penicillins, though SSSS from MRSA has been reported primarily in the adult population with other comorbidities. Clindamycin should be considered in those with severe illness to inhibit bacterial ribosomal exotoxin production.

Corticosteroids should not be given and topical antibiotics have not been shown to be effective.² Supportive skin care should be provided, specifically the use of thick emollients along with semi-occlusive, nonadherent dressings changed once to twice daily to improve barrier function, similar to how burns are treated. Applying tape in direct contact with skin should be avoided due to the significant epidermal fragility. Hydration status and electrolytes should be monitored closely. Appropriate analgesia should also be administered.³ Depending on the severity of skin involvement, admission to the intensive care unit (ICU) or a burn unit may be necessary. Serious complications can develop such as pneumonia, hypothermia, electrolyte derangements, dehydration, and secondary infections even with optimum therapy. Mortality rates for children remain below 5% but approach 60% in immunocompromised adults. Recurrence is not expected due to the development of neutralizing antibodies, though this has been reported in the context of immunosuppression.

ADMISSION CRITERIA

Admission should be initiated as soon as SSSS is suspected due to the need for microbial cultures, early initiation of intravenous antibiotics, administration of analgesia, and facilitation of supportive skin care, though outpatient therapy may be an option for older children as their disease tends to be milder and indistinguishable from bullous impetigo.^1,3 ICU or burn unit transfer may be required if fluid and electrolytes are difficult to normalize, if temperature control becomes difficult, if the patient becomes hemodynamically unstable, or if extensive time is needed to provide supportive skin.

DISCHARGE CRITERIA

An appropriate course of intravenous antibiotics (48 to 72 hours) should be completed, with transition to an oral regimen prior to discharge. The patient must be hemodynamically stable, maintaining adequate hydration and nutrition orally. Pain should be absent or well controlled. Caregivers should be able to provide all necessary supportive skin care, though home nursing services may be an option for some families.

CONSULTATION

Dermatology can assist with diagnosis, specifically if a skin biopsy is indicated to exclude TEN. Infectious diseases consultation can guide initial and ongoing antibiotic recommendations. Wound care specialists can advise and assist with emollients and dressing needs. Critical care may be needed if any complications develop. Infection control services should be involved if an outbreak is suspected.

SPECIAL CONSIDERATIONS

Patients with severe allergy to penicillin may receive cefazolin, clindamycin, or vancomycin. Antibiotic sensitivities should ultimately dictate therapy.

PREVENTION

Close attention to hand hygiene and institution of contact precautions is paramount to prevent the development of outbreaks, which have been reported in multiple nurseries.²

BACKGROUND

Cellulitis and erysipelas refer to diffuse, spreading skin infections that develop as a result of bacterial entry via breeches in the skin barrier and which manifest as areas of skin erythema, edema, and warmth. Both conditions most commonly involve the lower extremities and are excluded in the presence of infections with suppurative foci such as abscesses, necrotizing fasciitis, septic arthritis, and osteomyelitis.⁴ They are distinguished from one another in several important aspects, primarily by the depth of infection. Specifically, cellulitis is an acute, noncontagious infection of the skin and subcutaneous tissue. Erysipelas affects the upper dermis with prominent lymphatic involvement. The bright red color and sharp line of demarcation from normal skin help differentiate erysipelas from cellulitis. Both conditions require prompt diagnosis and antibiotic therapy. The majority of children can be managed safely and effectively in the outpatient setting, but hospital admission may be prudent in some cases.

PATHOPHYSIOLOGY

The most common causative organisms of cellulitis are Streptococcus pyogenes (group A β-hemolytic streptococcus, GABHS) and S. aureus, but other gram-positive bacteria such as Streptococcus pneumoniae and group C or G streptococci may be involved.⁴ GABHS is by far the most common causative organism of erysipelas, although group B, C, D, and G streptococci and, uncommonly, S. aureus, Klebsiella pneumoniae, and Yersinia enterocolitica may be involved.¹ Although not reliable distinguishing features, infection with S. aureus tends to be more localized and suppurative, whereas S. pyogenes tends to spread more rapidly with associated lymphangitis. Portals of entry for the infection include an abrasion, ulcer, body piercing, insect or animal bite, surgical site, and toe web fissure.⁵ Breeches in the skin may be small and clinically unapparent. Venous and lymphatic damage from past surgeries, trauma, thromboses, or congenital vascular malformations may result in chronic limb edema and serve as significant predisposing factors for cellulitis.⁴

CLINICAL PRESENTATION

Cellulitis presents as ill-defined erythema, warmth, edema, and pain in a child who may have the indolent onset of systemic symptoms of fever, chills, and malaise.⁵ Although a leading edge of the erythema can sometimes be determined, this edge is not raised or sharply demarcated from the adjacent normal skin (Figure 106-3). Bullae and petechiae may be noted in dependent limbs.

Periorbital (preseptal) cellulitis deserves special mention due to its potential confusion with the more concerning diagnosis of orbital cellulitis. Periorbital cellulitis is limited to the periorbital tissues and while often due to skin trauma, it can also occur via spread of Haemophilus influenzae or S. pneumoniae from the paranasal sinuses or bloodstream. If the infection crosses the orbital septum, it may result in orbital cellulitis, which is concerning for its potential to cause orbital abscesses as well as cavernous sinus thrombosis. Patients with orbital cellulitis may present with proptosis, ophthalmoplegia, and decreased visual acuity, in which case computed tomography (CT) imaging and ophthalmology consultation are indicated.¹

Perianal streptococcal dermatitis (sometimes referred to as cellulitis) is also a distinct clinical entity that is important to recognize. It may be associated with rectal itching, painful defecation, blood-streaked stools, and constipation. Fever is rare but a concomitant streptococcal pharyngitis is sometimes present.¹

Erysipelas is characterized by the abrupt onset of fever, chills, and malaise, followed by the development of a warm, shiny, bright red, confluent, indurated, tender plaque with elevated, sharply defined margins (Figure 106-4). The tenderness can be striking, leading to its alternative name of “St. Anthony’s Fire.”⁶ Lymphatic involvement can lead to a “peau d’orange” appearance.⁵ The lower extremity is the most common location, but the face and other areas can be affected. Involvement of the ear (Millian’s ear sign) is a distinguishing feature of erysipelas as this region does not contain deeper dermal tissue.⁵

Distinct clinical settings or presentations may suggest alternative infectious agents. In neonates, group B Streptococcus (GBS) should be suspected and a full septic workup instituted.¹ Buccal cellulitis, a purplish-red swelling of the cheek, suggests infection with H. influenzae type B, but this is rarely seen since the advent of routine immunization. With infection following cat or dog bites, the responsible organism is typically Pasteurella multocida or Capnocytophaga canimorsus.⁴ Infection after contact with fresh or salt water should raise the possibility of Aeromonas hydrophila or Vibrio vulnificus, respectively. Crepitation suggests infection with clostridia or non-spore-forming anaerobes such as Bacteroides species, peptostreptococci, and peptococci.⁵ Circumstances such as frequent subcutaneous injection of medications (e.g. insulin) or illicit drugs (“skin popping”) as well as iatrogenic or congenital immunosuppression open the door to a large array of bacterial, fungal, and mycobacterial organisms, necessitating greater scrutiny in terms of diagnosis and management.⁴