What is the diagnosis and treatment for a patient with erysipelis (infection of the upper dermis)?

Diagnosis and Treatment of Erysipelas

Diagnosis

Erysipelas is diagnosed clinically based on the acute onset of a painful, erythematous, infiltrated plaque with well-defined margins, accompanied by fever and often regional lymphadenopathy. 1, 2

Key Clinical Features to Identify

• Local findings: Look for a sharply demarcated, raised, erythematous plaque that is warm, tender, and edematous—the subcutaneous tissues remain yielding to palpation (unlike necrotizing fasciitis where tissues feel wooden-hard) 3, 2
• Systemic signs: Fever is present in only 25% of cases, though high fever with sudden onset is characteristic when present 2, 4
• Associated findings: Lymphangitis and regional adenopathy occur in 20-70% of cases 5
• Location: Lower extremities are affected in 76-80% of cases, followed by face (17%) and upper extremities (6%) 2, 4

Essential Portal of Entry Examination

• Examine interdigital toe spaces for tinea pedis, fissuring, or maceration—athlete's foot is the most common portal of entry 1, 2
• Identify other potential entry sites including chronic ulcers, eczema, or minor trauma 1, 2

Laboratory Testing

• Blood cultures are NOT routinely indicated—they are positive in only 3-5% of cases and do not change management in typical presentations 1, 5
• Elevated ESR occurs in 60% of cases but is not required for diagnosis 4
• Routine blood work is unnecessary for uncomplicated cases 6

Critical Differential Diagnoses to Exclude

• Necrotizing fasciitis: Distinguished by wooden-hard subcutaneous tissues, skin anesthesia, rapid progression, and severe systemic toxicity—requires immediate surgical consultation 3
• Contact eczema, venous stasis dermatitis, acute arthritis, and deep vein thrombosis 6, 5

Treatment

First-line treatment is penicillin (oral or IV depending on severity) for 5-10 days, as erysipelas is primarily caused by Group A Streptococcus pyogenes. 1, 2

Outpatient Oral Therapy (Uncomplicated Cases)

• Penicillin V 500 mg orally every 6-8 hours for 5-7 days is the gold standard 1
• Amoxicillin 500 mg orally three times daily for 5-7 days is an equally effective alternative 1, 2
• Duration: 5 days is as effective as 10 days if clinical improvement is evident at day 5 1

Penicillin Allergy Alternatives

• Clindamycin 300-450 mg orally every 6-8 hours is the preferred alternative for penicillin allergy 1, 7
• Erythromycin 250 mg orally four times daily, though resistance is a concern 1, 2

Inpatient IV Therapy (Severe Cases)

Hospitalize immediately if: systemic inflammatory response syndrome (SIRS), hypotension, altered mental status, severe immunocompromise, or concern for necrotizing infection 7

• Penicillin G 12-24 million units/day IV divided every 4-6 hours for severe streptococcal infections 8
• For severe penicillin allergy: Vancomycin 30 mg/kg/day IV in 2 divided doses or Clindamycin 600 mg IV every 8 hours 1

Important Treatment Nuance

• Do NOT empirically cover MRSA in typical erysipelas—it is caused by streptococci, not staphylococci 1, 2
• Consider MRSA coverage only if patient has risk factors for CA-MRSA or fails first-line streptococcal therapy 1
• Penicillin demonstrates shorter duration of fever after treatment initiation (1.7 vs 4.5 days) compared to other antibiotics 4

Essential Adjunctive Measures

• Elevate the affected limb above heart level for at least 30 minutes three times daily to promote drainage 1, 7
• Treat the portal of entry: Apply topical antifungals for tinea pedis, manage eczema, keep skin well-hydrated with emollients 1, 7
• Bed rest during acute phase 2
• Anticoagulation prophylaxis for patients at risk of venous thromboembolism 2

Prevention of Recurrence

Recurrence is the most common complication of erysipelas and requires aggressive management of predisposing factors. 2, 9

• Treat underlying conditions: Tinea pedis with topical antifungals, venous insufficiency with compression stockings, lymphedema with elevation and compression 1, 7
• Maintain skin integrity: Regular use of emollients to prevent cracking 1
• Prophylactic antibiotics if ≥3 episodes per year despite treating predisposing factors: Penicillin V 250 mg orally twice daily or benzathine penicillin 1.2 million units IM monthly 7

Common Pitfalls to Avoid

• Do not prolong antibiotics beyond 5-7 days for uncomplicated cases—this increases resistance without improving outcomes 1
• Do not order blood cultures, tissue aspirates, or skin biopsies for typical presentations—they have extremely low yield and delay treatment 1, 5
• Do not confuse erysipelas with necrotizing fasciitis—failure to recognize the wooden-hard subcutaneous tissue and rapid progression of necrotizing infection can be fatal 3
• Do not add anti-staphylococcal coverage empirically—this is unnecessary and promotes resistance 2, 5