Erysipelas and cellulitis

Erysipelas is an acute infection caused by Streptococcus pyogenes involving the dermis and dermal lymphatics. It usually affects the face or extremities and initially forms erythematous skin lesions with sharply demarcated, raised edges that rapidly enlarge. These can form a red, swollen, warm, hardened and painful rash, often with a characteristic ‘orange peel’ appearance.

Cellulitis, unlike erysipelas, involves the subcutaneous tissue, and is most commonly caused by Streptococcus pyogenes or Staphylococcus aureus. Cellulitis presents with an acute onset of red, painful, hot, swollen and tender skin. The inflammation spreads and there may also be blistering. Fever, malaise, nausea, shivering and rigors may accompany or precede the skin changes.

Chronic oedema, stasis dermatitis and breaks in the skin (e.g. bites, burns and lacerations) can all predispose to the development of cellulitis. Tinea pedis (athlete’s foot) is the commonest portal of entry associated with leg cellulitis.

In practice it can be difficult to distinguish between erysipelas and cellulitis. Anyone with suspected erysipelas or cellulitis should be referred to their GP for antibiotic treatment.

Only people with mild or moderate cellulitis with no systemic illness or uncontrolled comorbidities should usually be managed in primary care. Patients who are systemically unwell and/or have comorbidities (e.g. arterial disease, morbid obesity) will require hospital admission.