Erysipelas

Overview

Definition

Erysipelas is an infection of the skin involving the upper dermis and superficial lymphatics.

Epidemiology

• Exact incidence is unknown.
• Most commonly affects young children and elderly adults.
• Lower extremities are most common site of involvement, followed by the face.
• 29% of patients recur within 3 years.

 Etiology

• Most common agent:
  • Group A beta-hemolytic Streptococcus (S. pyogenes) 
• Less common agents: 
  • Staphylococcus aureus (in cases of bullous erysipelas)
  • Group B Streptococcus (in neonates)
• Risk factors:
  • History of minor skin trauma
  • Lymphedema
  • Arteriovenous insufficiency
  • Immunodeficiency
  • History of recent mastectomy, pelvic surgery, or bypass (impaired lymphatic drainage)
  • Animal bites, including insects and dogs
  • Underlying dermatological conditions, such as eczema, psoriasis, or cutaneous lupus
  • Diabetes mellitus

Pathophysiology and Clinical Presentation

Pathophysiology

• Bacteria enter disrupted skin barrier (e.g., ulcer, blister, dog bite).
• Invasion of the upper dermis produces erythema and local swelling of the skin (edema).
• Spread of bacterial agent and inflammatory cytokines via superficial lymphatic vessels.
• Unlike cellulitis:
  • Does not penetrate deep dermis and subcutaneous tissue
  • Always non-purulent

Clinical presentation

• Acute onset
• Usually associated and may be preceded with systemic symptoms:
  • High fever and chills
  • Muscle and joint pain
  • Nausea and vomiting
  • Headache
  • General malaise
• Commonly involves legs, hands (unilateral), and face
• Erythema:
  • Sharply demarcated
  • Raised advancing border sometimes with central clearing
  • “Butterfly sign” on the face
  • “Milian’s ear sign”: ear erysipelas
  • “Peau d’orange” appearance: dimpling of the skin due to edema around hair follicles
• Edema
• Warmth
• Tenderness
• Lymphangitis: red streaking radiating from the lesion
• Regional lymphadenopathy
• More severe presentations:
  • Cutaneous hemorrhage, petechiae and necrosis
  • Vesicles, blisters, and bullae (Staphylococcal toxin has been implicated)

Diagnosis and Management

Diagnosis

History:

• Local skin trauma:
  • Scratches
  • Needle pricks
  • Animal bites
• Underlying medical conditions and immune deficiencies
• History of prior skin infections
• Recent soft-tissue surgeries

Physical exam:

• Characteristic well-demarcated erythematous plaques
• Lymphadenopathy
• Fever

Laboratory studies:

• Not necessary in uncomplicated cases.
• Elevated white blood cell count
• Inflammatory markers (erythrocyte sedimentation rate, C-reactive protein) may be elevated.

Imaging:

• Not necessary, if the diagnosis is clear
• Soft tissue ultrasound: can rule out abscess and deeper infection
• Computerized tomography (CT) with IV contrast/magnetic resonance imaging (MRI): to rule out another process

Cultures:

• Blood and wound cultures are not routinely indicated.
• Blood cultures for severe systemic symptoms/sepsis.
• Wound cultures:
  • In immunocompromised patients, if an unlikely organism is possible.
  • In recurrent infections

Management

Uncomplicated cases:

• Oral antibiotics for 5–14 days:
  • Oral penicillin (amoxicillin)
  • Cephalosporin (if allergic to penicillin)
  • Clindamycin
• Elevation of affected extremity to reduce swelling
• Cold compresses
• Symptomatic fever and pain management

Cases requiring hospitalization and intravenous (IV) antibiotics:

• Severe presentation: bullae/blistering, skin necrosis, signs of sepsis
• Elderly
• Infants
• Immune compromise/poorly controlled diabetes
• Failure to improve with oral antibiotics
• IV antibiotics:
  • Need to have Streptococcal and Staphylococcal coverage
  • Cefazolin, ceftriaxone, or clindamycin

Surgical debridement: may be required for severe cases with skin necrosis

Differential Diagnosis

• Cellulitis: is a common and painful bacterial skin infection that affects the deeper layers of the dermis and subcutaneous tissue. Presents as an erythematous, edematous area that feels warm and tender to touch. This condition is caused most commonly by S. aureus and S. pyogenes. Diagnosis is usually clinical and management is antibiotics based on suspected organisms.
• Necrotizing fasciitis: a rapidly progressive infection resulting in extensive necrosis of subcutaneous tissue, fascia, and muscle. Most commonly caused by group A Streptococcus but often involves other types of bacteria in a mixed infection. Presents with necrosis, crepitus, bullae, and purple skin discoloration. Management is emergent surgical debridement with broad-spectrum antibiotics.
• Dermatitis: a general term for an edematous skin rash. This condition is caused by an infection or an allergic reaction, usually not by bacteria. Management is with antihistamines and topical steroids.
• Folliculitis: a localized inflammation of the hair follicle or sebaceous glands primarily caused by S. aureus. Presents as erythema, papules, pustules, and tenderness of the affected area.
• Impetigo: a highly contagious skin infection of the upper epidermis. This condition is caused by S. aureus or group A streptococci. Presents with an erythematous area covered in small vesicles, pustules, and/or honey-colored crusts. Management is with antibiotics.
• Staphylococcal scalded skin syndrome: a blistering skin disorder caused by a local infection usually due to S. aureus. Presents with fever and diffuse, tender erythema, intraepidermal blisters, and sloughing off of the superficial layer of skin, leaving a red “scalded” appearance.  Management involves IV antibiotics.