Erysipelas

What erysipelas is

Erysipelas is an infection of the dermis, the layer just under the skin's surface, and the superficial lymph vessels. Because the infection is high in the skin, the inflamed area stands up slightly above normal skin and has a crisp, well-defined border you can feel with a fingertip. Cellulitis, by contrast, involves the deeper dermis and the fat below and has a flatter, blurred edge.

Some doctors, especially in Europe, use "erysipelas" for any superficial cellulitis. The distinction matters mostly for which bacteria are likely and which antibiotic to choose.

Symptoms of erysipelas

• Sudden fever, chills, shivering and feeling unwell, often 4 to 48 hours before the skin changes
• A bright red, hot, tender, shiny patch with a raised, sharply marked edge
• Swelling of the area; on the face it can close an eyelid
• Rapid spread, sometimes several centimeters in a day
• Blisters (bullous erysipelas), sometimes filled with blood
• Red streaks running up the limb (lymphangitis) and tender, swollen lymph nodes in the groin or armpit

On the face, erysipelas often covers both cheeks and the bridge of the nose in a butterfly shape and may involve the ear. Involvement of the ear helps tell it apart from cellulitis, because the ear has no deep fat layer.

Causes

Most erysipelas is caused by group A Streptococcus (Streptococcus pyogenes), the same germ that causes strep throat. Groups B, C and G streptococci cause some cases. Staphylococcus aureus is less common.

The bacteria enter through a break in the skin, often one that is tiny or unnoticed:

• athlete's foot cracks between the toes
• cuts, scratches, insect bites, ulcers or surgical wounds
• eczema or other cracked, dry skin
• a recent nose or throat infection, for facial erysipelas

Risk factors

• Swollen legs from lymphedema or chronic venous insufficiency, the strongest risk factors
• A previous episode of erysipelas or cellulitis
• Obesity
• Diabetes
• Leg ulcers and skin conditions on the legs
• Surgery that removed lymph nodes, such as for breast cancer or melanoma, or vein harvesting for heart bypass
• Older age and a weakened immune system

Erysipelas vs cellulitis

Conditions that can look similar include deep vein thrombosis, contact dermatitis, venous (stasis) dermatitis, gout and an early shingles rash. Stasis dermatitis usually affects both legs, itches more than it hurts, and comes without fever.

How erysipelas is diagnosed

The diagnosis is clinical, based on the appearance of the skin and the sudden fever. Doctors often draw around the edge of the redness with a pen to track whether it spreads or shrinks.

Tests are usually only done if you are very unwell, the diagnosis is unclear or treatment is failing:

• blood count and CRP to measure inflammation
• blood cultures if there are signs of sepsis
• a swab of any open wound or blister
• an ultrasound to rule out a DVT or find an abscess

Treatment

• Antibiotics: penicillin or amoxicillin is first choice because of the strong link to strep. People allergic to penicillin often take clindamycin or a macrolide. Mild cases take tablets for 5 to 7 days, extended if the skin is still improving slowly. Severe cases or facial infection may need IV antibiotics in the hospital.
• Rest and raise the limb above the level of the heart to reduce swelling.
• Pain and fever relief: acetaminophen (paracetamol) or ibuprofen at the label dose.
• Treat the entry point: antifungal cream for athlete's foot, moisturizer for cracked skin, care for any ulcer.
• Drink enough fluids, especially with fever.

The redness may look worse in the first 24 to 48 hours of antibiotics as toxins are released, then it should fade. The fever usually settles within 1 to 2 days. Peeling of the skin as it heals is normal.

Complications

• Abscess formation
• Spread into the blood (sepsis)
• Rarely, necrotizing fasciitis
• Damage to the lymph vessels, causing lasting lymphedema, which raises the chance of another episode
• Rarely, kidney inflammation (post-streptococcal glomerulonephritis)

Preventing erysipelas from coming back

Erysipelas recurs in roughly a third of people within a few years. To lower the risk:

• Treat athlete's foot promptly and dry carefully between the toes.
• Moisturize dry, cracked skin on the legs and feet every day.
• Control leg swelling with compression stockings, raising the legs and lymphedema care.
• Lose weight if you are overweight, and keep diabetes well controlled.
• Protect skin from cuts and insect bites, and clean any wound promptly.

People with 2 or more episodes a year despite these steps may be offered long-term low-dose penicillin to prevent further attacks.

Frequently asked questions

Is erysipelas contagious?

Not in normal contact. The infection is inside the skin, so touching the red area does not usually spread it. The strep bacteria can spread from an open, weeping wound or blister, so cover it and wash your hands after touching it.

How long does erysipelas take to heal?

Fever usually settles within 1 to 2 days of starting antibiotics. The redness and swelling fade over 1 to 2 weeks, and the skin may peel. Leg swelling can take several weeks to settle completely, especially if you already had swollen legs.

What is the difference between erysipelas and cellulitis?

Erysipelas affects the upper layers of the skin and has a raised, sharply defined, bright red edge. Cellulitis goes deeper into the fat under the skin, so its edge is flat and blurred. Both are bacterial skin infections treated with antibiotics.

Why does erysipelas keep coming back?

Each episode can damage the lymph vessels, leaving the leg more swollen and more vulnerable. Untreated athlete's foot, cracked skin, venous leg swelling, obesity and diabetes also keep the door open to bacteria. Treating these reduces repeat episodes.

Can erysipelas appear on the face?

Yes. Facial erysipelas often spreads across the cheeks and nose and may involve the ears and eyelids. It needs prompt medical care, and urgent care if the eye is swollen shut or eye movement is painful, because infection near the eye can spread deeper.