Summary

Erysipelas is an acute, superficial bacterial skin infection involving the upper dermis and superficial lymphatics. It is almost always caused by Group A Streptococcus (Streptococcus pyogenes). The classic presentation is a well-demarcated, raised, bright red plaque with an advancing, sharply defined border. Unlike cellulitis, erysipelas is more superficial and has clear margins. The face and lower legs are the most common sites. Patients typically present with sudden-onset fever, rigors, and malaise. Treatment is with penicillin-based antibiotics. The prognosis is excellent with appropriate treatment.

Key Facts

• Organism: Group A Streptococcus (Strep pyogenes) - 80%+
• Depth: Upper dermis and superficial lymphatics (superficial)
• Classic Sign: Well-demarcated, raised, bright red plaque
• Site: Face (20%), Lower leg (70%)
• Treatment: Penicillin V (oral) or Benzylpenicillin (IV if severe)
• Prognosis: Excellent with treatment; recurrence common (30%)

Clinical Pearls

"Sharp Edges = Erysipelas, Blurry Edges = Cellulitis": Erysipelas has well-demarcated, raised borders. Cellulitis has indistinct, merging edges. This is the key clinical distinction.

"Fever Comes First": Patients often have rigors and high fever BEFORE the rash appears. This can cause diagnostic confusion.

"The Malar Butterfly": Classic facial erysipelas spares the nasolabial folds and mimics a butterfly pattern, similar to lupus rash - but erysipelas is hot, tender, and the patient is unwell.

"Recurrence is Common": 30% get recurrent erysipelas. Identify and treat predisposing factors (lymphoedema, tinea pedis, venous insufficiency).

Vital Signs

• Fever (often >38°C)
• Tachycardia
• May be hypotensive if septic

Inspection

• Bright red, shiny plaque
• Well-demarcated, raised edge
• "Peau d'orange" texture (skin pitting)
• Bullae in severe cases

Palpation

• Warm to touch
• Tender
• Palpable raised edge demarcates from normal skin

Differentiation from Cellulitis

Look for Entry Point

• Tinea pedis (between toes)
• Leg ulcer
• Trauma/abrasions
• Eczema

With Treatment

• Excellent prognosis
• Most improve within 48-72 hours
• Full resolution within 1-2 weeks

Recurrence

• 30% recurrence rate
• Prevention: Treat underlying factors, prophylactic antibiotics if recurrent

Prophylaxis for Recurrent Erysipelas

• Penicillin V 250mg BD long-term (or Erythromycin if allergic)
• Reduces recurrence by 50%

Key Guidelines

1. NICE CKS: Cellulitis and Erysipelas
2. CREST Guidelines: Management of Cellulitis
3. British Dermatology Guidelines

Key Evidence

Antibiotics

• Penicillin remains first-line (Group A Strep sensitivity)
• No proven benefit of anti-staphylococcal agents in typical erysipelas

Prophylaxis

• RCTs show long-term penicillin reduces recurrence by ~50%

What is Erysipelas?

Erysipelas is a skin infection caused by bacteria, usually streptococcus ("strep"). It causes a bright red, hot, swollen area on the skin with a clearly defined edge. It most commonly affects the face or lower legs.

What Causes It?

Bacteria enter through a break in the skin, such as:

• Athlete's foot (cracked skin between toes)
• Cuts or grazes
• Leg ulcers
• Eczema

What Are the Symptoms?

• Sudden onset of fever, chills, and feeling unwell
• A bright red, painful, swollen area of skin
• The edge of the redness is clearly defined and raised
• The affected area feels hot

How is it Treated?

Antibiotics are very effective. Most people get oral antibiotics to take at home. If you're very unwell, you may need antibiotics through a drip in hospital.

You should also:

• Rest with the affected limb raised
• Take paracetamol for pain and fever
• Drink plenty of fluids

How Long Does it Take to Get Better?

You should start to feel better within 2-3 days. The redness may take 1-2 weeks to completely disappear.

Can it Come Back?

Yes, about 1 in 3 people get erysipelas again, especially if there's an underlying problem like lymphoedema or athlete's foot. Treating these conditions helps prevent recurrence.