Erysipelas
Erysipelas is a superficial bacterial skin infection with prominent dermal lymphatic involvement, almost always caused by group A Streptococcus, producing a painful, sharply demarcated, raised, indurated plaque with a peau d'orange surface. Diagnosis is clinical from the border and depth of involvement, and first-line treatment is oral cephalexin, with intravenous cefazolin for systemic signs and long-term penicillin V for confirmed recurrence.
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What this article covers
- Overview
Definition: erysipelas is a superficial bacterial skin infection confined largely to the upper dermis and its lymphatic channels, distinct from the deeper, less sharply bordered infection of ordinary cellulitis.
- Epidemiology
Age distribution: occurs at both extremes of life, most often in elderly adults and infants.
- Risk factors
Portal of entry: any break in the epidermis, including tinea pedis, toe-web maceration, minor trauma, or a chronic wound, lets streptococci reach the dermis.
- Pathophysiology
Superficial invasion: streptococci enter through a skin-barrier defect and proliferate within the upper dermis and its lymphatic channels rather than the deeper dermis and subcutaneous fat involved in cellulitis.
- Clinical features
Diagnostic morphology: a tender, warm, erythematous plaque that is raised and indurated, with a peau d'orange surface and a border sharply demarcated from adjacent normal skin, the combination that defines the clinical diagnosis.
- Differential diagnosis
Cellulitis: involves the deeper dermis and subcutaneous fat, is tender and warm but lacks the sharp demarcation and raised border of erysipelas, and tends to progress over days rather than hours.
- Diagnosis
Clinical diagnosis from morphology and depth establishes the diagnosis first: the combination of a painful, raised, sharply demarcated plaque with a peau d'orange surface, evolving over hours…
- Management
First-line, oral therapy for mild, nonpurulent disease without immediate beta-lactam hypersensitivity: cephalexin 500 mg PO four times daily for 5 days, extending treatment if the infection has not clearly improved by day 5.
- Complications
Streptococcal toxic shock syndrome: a life-threatening systemic complication reported in association with erysipelas, driven by exotoxin-producing strains.
- Prognosis
Generally favorable with prompt treatment: most patients improve within days of starting an appropriate antibiotic.
- Prevention
Eliminate the portal of entry: treat interdigital tinea pedis and other chronic breaks in the skin barrier promptly.
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