What is erysipelas?
Erysipelas is a superficial form of cellulitis, a potentially serious bacterial infection affecting the skin. Unlike cellulitis, almost all erysipelas is caused by Group A beta haemolytic streptococci (Streptococcus pyogenes).
Who gets erysipelas?
Erysipelas most often affects infants and the elderly, but can affect any age group. Risk factors are similar to those for other forms of cellulitis.
- Previous episode(s) of erysipelas
- Venous disease (eg gravitational eczema, leg ulceration) and/or lymphoedema
- Current or prior injury (eg trauma, surgical wounds, radiotherapy)
What are the clinical features of erysipelas?
Erysipelas predominantly affects the skin of the lower limbs, but when it involves the face it can have a characteristic butterfly distribution on the cheeks and bridge of the nose.
Symptoms and signs of erysipelas are usually abrupt in onset and often accompanied by general illness in the form of fevers, chills and shivering.
- Affected skin is distinguished from other forms of cellulitis by a well-defined, raised border.
- The affected skin is red, firm, swollen and may be finely dimpled (like an orange skin).
- It may be blistered.
- Bleeding into the skin may cause purpura (purple patches).
- Cellulitis does not usually exhibit such marked swelling but shares other features with erysipelas such as pain and increased warmth of affected skin.
What is the treatment for erysipelas?
Most streptococcal bacteria causing erysipelas are sensitive to penicillin antibiotics. Penicillin, either orally or intravenously (if patient is very unwell), is the antibiotic of first choice. Erythromycin may be used as an alternative in patients with penicillin allergy. Treatment is usually for 10-14 days, and while signs of general illness resolve within a day or two, the skin changes may take some weeks to resolve completely. No scarring occurs.
Erysipelas recurs in up to one third of patients due to persistence of risk factors and also because erysipelas itself can cause lymphatic damage (hence impaired drainage of toxins) in involved skin which predisposes to further attacks.
If patients have recurrent attacks, long term preventive treatment with penicillin may be considered.
What are the complications of erysipelas?
Complications are rare but can include:
- Infections distant to the site of erysipelas via bloodstream spread, including infective endocarditis (heart valve infection) and septic arthritis (infected joints)
- Post-streptococcal glomerulonephritis (a kidney condition affecting children)
- Cavernous sinus thrombosis (dangerous blood clots that can spread to the brain)
- Streptococcal toxic shock syndrome (rare)