Erysipelas

Introduction | Aetiology and Risk Factors | Clinical Presentation | Diagnosis | Management and Treatment | When to Refer | References

Introduction

Erysipelas is an acute bacterial skin infection that involves the upper dermis and extends into the superficial lymphatics. It is characterised by a well-demarcated, bright red, and often raised rash, typically affecting the face or legs. Erysipelas is most commonly caused by Streptococcus pyogenes (group A streptococcus). The condition can progress rapidly and requires prompt treatment to prevent complications.

Aetiology and Risk Factors

Erysipelas is primarily caused by bacterial infection, with Streptococcus pyogenes being the most common pathogen. Other factors that can predispose individuals to erysipelas include:

• Skin Breaks: Entry points for bacteria, such as cuts, abrasions, insect bites, or surgical wounds, increase the risk of infection.
• Impaired Lymphatic Drainage: Conditions that impair lymphatic drainage, such as lymphedema or previous surgeries, can predispose to erysipelas.
• Chronic Skin Conditions: Conditions like eczema, psoriasis, or athlete’s foot can disrupt the skin barrier and facilitate bacterial entry.
• Immunosuppression: Individuals with weakened immune systems, such as those with diabetes, HIV, or on immunosuppressive medications, are at higher risk.
• Venous Insufficiency: Chronic venous insufficiency or varicose veins can lead to stasis and increase susceptibility to infection.
• Obesity: Obesity is a risk factor due to the increased likelihood of skin folds, which can harbor bacteria and moisture.
• Age: Elderly individuals are more susceptible due to age-related immune decline and often having multiple comorbidities.

Clinical Presentation

Erysipelas typically presents with the following features:

• Bright Red Rash: The affected area is usually bright red, with a well-demarcated edge. The rash is often raised and warm to the touch.
• Swelling: The area may be swollen and tender, with some patients experiencing a burning sensation.
• Fever and Malaise: Systemic symptoms such as fever, chills, and malaise are common and may precede the skin changes.
• Blisters or Bullae: In more severe cases, blisters or bullae may develop on the affected skin.
• Location: Erysipelas commonly affects the face, often starting near the ear, or the lower legs. Facial erysipelas may involve the eyelids and can spread rapidly.
• Lymphangitis: Red streaks extending from the erysipelas lesion, indicative of lymphangitis, may be present.
• Lymphadenopathy: Regional lymph nodes may be swollen and tender.

Diagnosis

The diagnosis of erysipelas is primarily clinical, based on the characteristic appearance of the rash and accompanying systemic symptoms:

• History: Take a detailed history, including the onset and progression of symptoms, recent skin injuries, and any underlying conditions that might predispose to infection.
• Physical Examination: Examine the skin for the classic signs of erysipelas, including the bright red, well-demarcated rash, swelling, and warmth. Check for systemic signs such as fever and lymphadenopathy.
• Differential Diagnosis: Consider other conditions that may mimic erysipelas, such as cellulitis, contact dermatitis, insect bites, herpes zoster, and deep vein thrombosis (if on the leg).
• Laboratory Tests: Blood tests may show elevated white blood cell count (leukocytosis) and inflammatory markers (CRP, ESR). Blood cultures may be taken in severe cases, though they are often negative.
• Imaging: Imaging studies like ultrasound may be used if there is a concern for deep tissue involvement or to rule out other conditions like deep vein thrombosis.

Management and Treatment

Management of erysipelas involves prompt antibiotic therapy to control the infection, along with supportive measures to reduce symptoms:

1. Antibiotic Treatment

• Penicillin: Penicillin is the first-line treatment for erysipelas. It can be administered orally or intravenously, depending on the severity of the infection.
• Amoxicillin: Amoxicillin is another effective option and is often used due to its broader spectrum of activity.
• Clarithromycin or Erythromycin: For patients allergic to penicillin, a macrolide antibiotic like clarithromycin or erythromycin can be used.
• Treatment Duration: The typical duration of antibiotic therapy is 7-14 days, depending on the severity and response to treatment.

2. Supportive Care

• Pain Relief: Analgesics such as paracetamol or ibuprofen can be used to manage pain and fever.
• Elevation: Elevating the affected limb can help reduce swelling and discomfort, particularly for erysipelas on the legs.
• Hydration: Encourage adequate fluid intake to help manage fever and support overall recovery.

3. Prevention and Patient Education

• Skin Care: Advise patients to keep the skin clean and moisturised to prevent cracking, which can provide an entry point for bacteria.
• Treat Underlying Conditions: Address any underlying conditions that may predispose to erysipelas, such as treating athlete’s foot or managing chronic venous insufficiency.
• Prophylactic Antibiotics: In patients with recurrent erysipelas, long-term prophylactic antibiotics may be considered to prevent recurrence.

When to Refer

Referral to a specialist or hospital admission may be necessary in the following situations:

• Severe or Rapidly Progressing Infection: If the infection is severe, rapidly spreading, or involves the face or periorbital region, hospital admission and intravenous antibiotics may be required.
• Complications: If complications such as abscess formation, necrosis, or systemic involvement (e.g., sepsis) occur, referral to a specialist or hospitalisation is necessary.
• Recurrent Erysipelas: Patients with recurrent episodes may benefit from referral to a dermatologist or infectious disease specialist for further evaluation and management.
• Uncertain Diagnosis: If the diagnosis is unclear or if there is concern for other conditions (e.g., deep vein thrombosis), referral for further evaluation may be warranted.

References

1. British Association of Dermatologists (2024) Guidelines for the Management of Erysipelas. Available at: https://www.bad.org.uk (Accessed: 26 August 2024).
2. National Institute for Health and Care Excellence (2024) Erysipelas: Diagnosis and Management. Available at: https://www.nice.org.uk/guidance/ng107 (Accessed: 26 August 2024).
3. British National Formulary (2024) Antibiotic Treatments for Skin Infections. Available at: https://bnf.nice.org.uk/ (Accessed: 26 August 2024).