Secondary impetigo with S. aureus is the most common secondary skin infection found in atopic dermatitis. Group Astreptococcus infection is also common. Infection manifests with pustules, erythema, crusting, scabbing, flare of disease, orlack of response to adequate anti-inflammatory therapy. Localized lesions can be treated with topical mupirocin. Widespreadand generalized lesions require oral antibiotic therapy, most commonly with a first-generation cephalosporin, such as cephalexin. Methicillin-resistant S. aureus infection is increasinglycommon, and antibiotic therapy should be tailored based onlocal resistance rates and patient factors. Diagnosis of super-infection may be made clinically, but a superficial bacterialculture can confirm the diagnosis and provide antimicrobialsusceptibilities. Treatment should include a concomitant atopicskin care routine including the continued use of topical corticosteroids. Although secondary skin infection with S. aureus is common, progression to cellulitis or septicemia is unusual.Rarely, intravenous antibiotics may nevertheless be required.Children with colonization and frequent infections may benefitfrom dilute bleach baths two to three times weekly; ¼ to ½ cupof household bleach is added to a half-full or full bathtub.
Eczema herpeticum (Kaposi’s varicelliform eruption) is oneof the potentially serious infectious complications in atopic dermatitis. After herpes simplex virus (HSV) infection, an eruption of multiple, pruritic, vesiculopustular lesions occurs in a disseminated pattern, both within plaques of atopic dermatitisand on normal-appearing skin. These characteristically ruptureand form crusted umbilicated papules and punched-out hemorrhagic erosions (Fig. 190-3). Irritability, anorexia, and fever canalso be seen. Systemic and central nervous system disease havebeen reported. Bacterial superinfection of eroded areas of the skin often occurs. Diagnosis can be made rapidly from a scrapingof the skin lesion stained with Giemsa or Wright’s stain (Tzanck test), though these are not highly sensitive. These stains allow microscopic visualization of the presence of multinucleatedgiant cells indicative of herpes simplex virus or varicella-zoster virus infection. Vesicle fluid can also be sent for polymerasechain reaction (PCR) detection of herpes simplex virus DNA, rapid direct fluorescent antibody testing, or viral culture. Laboratory confirmation of infection is important because similar clinical manifestations can occur with bacterial infections.
Figure 190-3 Eczema herpeticum (hand).
The psychosocial impact of atopic dermatitis can be significant. There is often disfigurement, lack of sleep from pruritus resulting in irritability and fatigue, and limitations on participation in sports. Significant time, as well as financial strain, is involved in caring for a child with atopic dermatitis. Thus, management should address these potential issues and provide adequate anticipatory guidance.
Atopic dermatitis frequently remits during childhood and is much less common after puberty. The condition is generally most severe and widespread in infancy and early childhood. Relapse of disease in adults can occur and commonly manifests as face or hand dermatitis. Frequently, adults have generalized dry skin and are aware that their skin is sensitive to many over-the-counter preparations. Patients with atopic dermatitis can also develop asthma and allergic rhinitis. Asthma is more commonly associated with more severe skin disease.