Cellulitis and erysipelas can usually be diagnosed based on history and examination only, although blood cultures and microscopic examination of cutaneous aspirates, biopsies, or swabs should be considered for selected patients, including those who are immunocompromised.
Prior episodes, preexisting lymphedema or venous insufficiency, diabetes, obesity, and tinea pedis can all predispose to cellulitis.
Antibiotics targeted at the most common etiologies (streptococci and Staphylococcus aureus) usually result in resolution.
Cellulitis is an acute spreading infection of the skin with visually indistinct borders that principally involves the dermis and subcutaneous tissue. It is characterized by erythema, edema, warmth, and tenderness, and most commonly occurs in the legs.
Erysipelas is a distinct form of superficial cellulitis with notable lymphatic involvement and is raised, sharply demarcating it from uninvolved skin.
Animal bites (including human bites), surgical wound infections, diabetic foot infections, and cellulitis or erysipelas in children and pregnant women are beyond the scope of this topic. See our topics "Animal bites" and "Diabetic foot infections".
History and exam
Key diagnostic factors
- skin discomfort
- macular erythema
- disruption of cutaneous barrier
- raised bright-red erythema with clearly demarcated margins (erysipelas)
- risk of infection with MRSA
Other diagnostic factors
- history of diabetes
- constitutional prodrome
- lymphangitis/regional lymphadenopathy
- Identifiable port of entry
- history of immunocompromise
- unusual exposure (salt or fresh water, bite)
- prior episode of cellulitis
- tinea pedis interdigitalis
- venous insufficiency/chronic leg edema
1st investigations to order
- purulent focus culture and molecular diagnostic procedures
Investigations to consider
- skin aspiration with culture and molecular diagnostic procedures
- blood culture
- skin biopsy
- plain film x-ray
- CT scan
- Necrotizing fasciitis
- Thrombophlebitis, superficial
- Deep vein thrombosis
- 2018 WSES/SIS-E consensus conference: recommendations for the management of skin and soft-tissue infections
- Practice guidelines for the diagnosis and management of skin and soft tissue infections
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