What are the causes of erysipelas?

Causes of Erysipelas

Erysipelas is primarily caused by beta-hemolytic streptococci, especially Streptococcus pyogenes (group A streptococci), which enter through breaches in the skin. 1, 2

Pathogenic Organisms

• Beta-hemolytic streptococci, particularly Streptococcus pyogenes (group A), are the predominant causative organisms 2
• Less commonly, other streptococci groups (B, C, G) may cause erysipelas 3
• Staphylococcus aureus is a rare cause, usually associated with previous penetrating trauma 3, 4
• Other rare infectious agents can cause cellulitis/erysipelas in specific circumstances:
  • Pasteurella species (especially P. multocida) or Capnocytophaga canimorsus following cat or dog bites 3
  • Aeromonas hydrophila after immersion in fresh water 3
  • Vibrio species (particularly V. vulnificus) after saltwater exposure in warm climates 3
  • Occasionally Streptococcus iniae or Erysipelothrix rhusiopathiae 3

Predisposing Factors and Entry Points

Skin Barrier Disruption

• Trauma to the skin, even minor and clinically inapparent breaks 3
• Preexisting skin infections such as impetigo or ecthyma 3
• Ulceration 3
• Fissured toe webs from maceration or fungal infection (tinea pedis) 3, 5
• Inflammatory dermatoses such as eczema 3

Local Risk Factors

• Lymphedema and lymphatic obstruction (strongest risk factor for recurrence with adjusted odds ratio of 19.6) 5
• Venous insufficiency 3, 4
• Obesity (adjusted odds ratio of 2.3 for recurrence) 5
• Previous cutaneous damage 3
• Intertrigo from fungal infections 6

Surgical Risk Factors

• Procedures that disrupt lymphatic drainage increase risk, including:
  • Saphenous venectomy 3
  • Axillary node dissection for breast cancer 3
  • Operations for gynecologic malignancies involving lymph node dissection, especially when followed by radiation therapy (radical vulvectomy and radical hysterectomy) 3

Mechanism of Recurrence

• Erysipelas has a high recurrence rate of up to 40% despite appropriate antibiotic treatment 6
• Intracellular uptake and persistence of streptococci within epithelial cells, endothelial cells, and macrophages creates reservoirs that are protected from penicillins 6
• These intracellular reservoirs may serve as endogenous sources for relapses, as penicillins do not reach sufficient bactericidal intracellular concentrations 6
• Recurrent episodes cause progressive lymphatic damage, resulting in irreversible lymphedema and ultimately elephantiasis nostras 6

Comorbidities Associated with Recurrence

• Hypertension 7
• Diabetes 7, 5
• Overweight/obesity 7, 5
• Venous insufficiency 7

Clinical Presentation

• Sudden onset with fever preceding skin manifestations 2
• Rapidly spreading areas of edema, redness, and heat 3
• Painful, infiltrated, erythematous plaque with distinct borders 2
• Sometimes accompanied by lymphangitis and inflammation of regional lymph nodes 3
• Skin surface may resemble orange peel (peau d'orange) due to superficial cutaneous edema 3
• Vesicles, bullae, and cutaneous hemorrhage in the form of petechiae or ecchymoses may develop 3
• Most commonly affects the lower limbs, but can occur on the face 2

Understanding these causes and risk factors is essential for both effective treatment and prevention of recurrence, which remains a significant clinical challenge in the management of erysipelas.