Cellulitis
Cellulitis is a nonpurulent, spreading infection of the deep dermis and subcutaneous fat, usually caused by beta-hemolytic streptococci, diagnosed clinically and treated with antibiotics alone since there is no collection to drain.
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What this article covers
- Overview
Definition: cellulitis is a nonpurulent, spreading bacterial infection of the deeper dermis and subcutaneous fat, with poorly demarcated borders, distinguishing it from erysipelas (upper dermis…
- Epidemiology
Common condition: cellulitis is one of the most frequent skin and soft tissue infections prompting outpatient and emergency evaluation.
- Risk factors
Breach of the epidermis: trauma (injection drug use, surgery, bites, lacerations, abrasions) or nontraumatic breaks (chronic ulcers, tinea pedis) provide the portal of entry.
- Pathophysiology
Causative organisms: nonpurulent, spreading skin infections such as cellulitis and erysipelas are usually caused by beta-hemolytic streptococci, chiefly Streptococcus pyogenes (group A strep)…
- Clinical features
Erythema with indistinct, non-elevated borders: the hallmark finding; unlike erysipelas, the margin blends gradually into normal skin rather than presenting a sharp, raised edge.
- Differential diagnosis
Skin abscess: a discrete, fluctuant, purulent collection is present; cellulitis has no drainable pus.
- Diagnosis
First, establish the diagnosis clinically: the pattern of poorly demarcated, spreading erythema, warmth, and tenderness in the deep dermis and subcutaneous tissue, without a fluctuant or purulent…
- Management
First, classify severity, then for mild cellulitis (no systemic signs): treat empirically as an outpatient with oral therapy directed against streptococci for a minimum of 5 days, extending the…
- Complications
Progression to necrotizing soft tissue infection: the most serious complication; suspect it with pain out of proportion to exam, hemorrhagic bullae, skin necrosis, crepitus, or rapid progression, and manage as a surgical emergency.
- Prognosis
Excellent with prompt appropriate therapy: most mild to moderate cases resolve fully with oral or intravenous antibiotics and leave no permanent tissue damage.
- Prevention
Treat portals of entry: manage tinea pedis with a topical or oral antifungal and treat chronic skin conditions (eczema, psoriasis, ulcers) that break skin integrity, since these predispose to recurrent infection.
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