Impetigo
Impetigo is a superficial epidermal infection caused by Staphylococcus aureus or group A streptococcus, presenting as bullous or, more commonly, nonbullous honey-crusted erosions, diagnosed clinically, and treated with topical mupirocin for localized disease or oral antistaphylococcal antibiotics for widespread, bullous, or MRSA-associated infection.
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What this article covers
- Overview
A superficial epidermal bacterial infection, not a deeper skin/soft tissue infection: impetigo is confined to the epidermis, distinguishing it from cellulitis or erysipelas, which involve the dermis and subcutaneous tissue.
- Epidemiology
Most common in children: impetigo is a pediatric-predominant infection, though it can occur in adults.
- Risk factors
Close contact with an infected person, particularly in children: household and childcare/school contact is the principal transmission route.
- Pathophysiology
Bullous impetigo is a toxin-mediated disease: S.
- Clinical features
Nonbullous impetigo (the hallmark presentation): erythematous papules or plaques that evolve into eroded lesions with a honey-colored crust, most often on the face; satellite lesions are common, and…
- Differential diagnosis
Cellulitis or erysipelas: involves the deeper dermis and subcutaneous tissue with poorly (cellulitis) or sharply (erysipelas) demarcated warmth, swelling, and tenderness, unlike the superficial, crusted, minimally tender lesions of impetigo.
- Diagnosis
First, the diagnosis is made clinically: honey-colored crust overlying eroded erythematous papules or plaques (nonbullous), or flaccid blisters rupturing into crusted erosions (bullous), is…
- Management
First, wash the affected area with soap and water and gently debride the crust as a standard initial step for all forms of impetigo, before or alongside antibiotic therapy.
- Complications
Poststreptococcal glomerulonephritis: classic infection-related glomerulonephritis develops 2 to 4 weeks after a group A streptococcal skin infection (versus 1 to 3 weeks after pharyngitis) due to…
- Prognosis
Excellent with appropriate topical or oral therapy: most cases of impetigo, nonbullous or bullous, resolve fully with a single course of topical or oral antibiotics.
- Prevention
Prompt treatment of active lesions limits household and close-contact spread: treating the index case and covering lesions reduces transmission to family members and classmates/daycare contacts.
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