What is the difference between erysipelas and cellulitis in terms of management and treatment?

Difference Between Erysipelas and Cellulitis

The primary distinction between erysipelas and cellulitis is anatomical depth: erysipelas affects the upper dermis and superficial lymphatics with well-defined borders, while cellulitis involves the deeper dermis and subcutaneous fat with poorly defined borders. 1, 2

Anatomical and Clinical Distinctions

Depth of Infection

• Erysipelas is limited to the upper dermis, including the superficial lymphatics 1
• Cellulitis involves the deeper dermis and subcutaneous fat 1

Border Characteristics

• Erysipelas presents with well-defined, clearly delineated borders of inflammation 1, 2
• Cellulitis demonstrates poorly defined borders with more diffuse spreading 2

Clinical Presentation Overlap

Both conditions share many clinical features, making them difficult to distinguish in practice 1:

• Rapidly spreading areas of erythema, swelling, tenderness, and warmth 1
• Lymphangitis and regional lymph node inflammation 1, 2
• "Peau d'orange" appearance due to superficial edema around hair follicles 1, 2
• Vesicles, bullae, petechiae, or ecchymoses may develop 1
• Systemic manifestations including fever, tachycardia, confusion, hypotension, and leukocytosis 1, 2

Management and Treatment Approach

Diagnostic Workup

For typical cases of either condition, blood cultures, tissue aspirates, or skin biopsies are unnecessary 1, 2. However, consider these investigations for:

• Patients with malignancy 1, 2
• Severe systemic features (high fever, hypotension) 1, 2
• Unusual predisposing factors (immersion injury, animal bites, neutropenia, severe immunodeficiency) 1

Antibiotic Selection

Both erysipelas and cellulitis should be treated with antibiotics active against streptococci, as these are the primary causative organisms 1, 2, 3:

First-Line Oral Options

• Penicillin 1
• Amoxicillin 1, 4
• Amoxicillin-clavulanate 1
• Dicloxacillin 1
• Cephalexin 1
• Clindamycin 1

Penicillin Allergy Alternatives

• Pristinamycin 4
• Clindamycin 4

Evidence on Antibiotic Classes

• Macrolides/streptogramins are more effective than penicillin antibiotics (RR 0.84,95% CI 0.73 to 0.97) 5
• Oral macrolides can be more effective than intravenous penicillin (RR 0.85,95% CI 0.73 to 0.98) in 3 trials with 419 participants 5
• No difference between penicillins and cephalosporins (RR 0.99,95% CI 0.68 to 1.43) 5

Treatment Duration

A 5-day course of antimicrobial therapy is as effective as a 10-day course if clinical improvement is seen at 5 days 2. This represents a significant shift from traditional longer courses.

Route of Administration

Most patients can receive oral medications from the start for typical cellulitis/erysipelas 1. Intravenous therapy is reserved for:

• Signs of severity 4
• Significant comorbidities (diabetes, arteritis, cirrhosis, immunodeficiency) 4
• Unfavorable social context 4

Adjunctive Measures

• Elevation of the affected area accelerates improvement by promoting gravity-driven drainage of edema and inflammatory substances 2
• Bed rest with leg elevation is important 3
• Anticoagulants are indicated in patients at risk of venous thromboembolism 3

Prevention of Recurrence

Recurrence is the most distressing complication, affecting approximately 25% of patients within 3 years 6, 7. Prevention strategies include:

Address Predisposing Factors

• Treat athlete's foot (tinea pedis), which is the most common portal of entry 3
• Manage venous insufficiency or lymphatic obstruction 1
• Address skin trauma, ulceration, fissured toe webs, or inflammatory dermatoses 1

Decolonization Regimens

For recurrent cases, consider 2:

• 5-day decolonization with twice-daily intranasal mupirocin 2
• Daily bathing with chlorhexidine 2
• Dilute bleach baths (1/4–1/2 cup per full bath) 2

Long-Term Prophylaxis

• Prophylactic antibiotic therapy with delayed penicillin is recommended for recurrent erysipelas 4
• Long-term antibacterial therapy is required for patients with recurrence 3

Common Pitfalls

Terminology Confusion

Physicians use "cellulitis" and "erysipelas" inconsistently 1:

• Some use "erysipelas" only for facial cellulitis 1
• In European countries, the terms are often used synonymously 1
• The distinction based on border definition is the most clinically useful approach 1, 2

Misdiagnosis

Do not label purulent collections as "cellulitis" 1. The term is inappropriate for:

• Cutaneous abscesses 1
• Septic bursitis 1
• Furuncles 1

Primary treatment of true cellulitis/erysipelas is antimicrobial therapy, whereas purulent collections require drainage as the major component of management 1.

Differential Diagnoses to Consider

When presentation is atypical, consider 3, 4:

• Contact eczema 4
• Acute arthritis or bursitis 4
• Chronic dermohypodermitis of venous origin 4
• Necrotizing fasciitis (if widespread petechiae/ecchymoses with systemic toxicity) 1
• Neutrophilic dermatoses or eosinophilic cellulitis 4