Erysipelas

Erysipelas is an acute superficial bacterial infection of the upper dermis and superficial lymphatics, most commonly caused by β-hemolytic streptococci, particularly Streptococcus pyogenes.

It is considered a more superficial and sharply demarcated form of cellulitis.The infection spreads rapidly through lymphatic channels, producing characteristic raised borders.

Most frequently affected sites:

• Face (classically butterfly distribution)

• Lower limbs (commonest overall)

• Arms

• Umbilical stump (neonates)

The disease has abrupt onset, marked systemic symptoms, and striking skin findings.

Etiology & Microbiology

Main pathogen

• Streptococcus pyogenes

Less common organisms

Pathophysiology

1. Entry through skin barrier defect

   • Fissures

   • Tinea pedis

   • Ulcers

   • Surgical wounds

   • Insect bites

2. Bacterial multiplication in superficial dermis

3. Lymphatic invasion

   • Causes raised sharply demarcated plaques

4. Release of streptococcal toxins

   • Fever and systemic toxicity

5. Inflammatory edema

   • Blistering and hemorrhage

Risk Factors

Local risk factors

• Tinea pedis (most common portal of entry)

• Chronic edema / lymphedema

• Venous insufficiency

• Skin trauma

• Surgical wounds

Systemic risk factors

• Diabetes mellitus

• Obesity

• Chronic kidney disease

• Alcoholism

• Immunosuppression

• Elderly age

• Malnutrition

Recurrence risk factors

• Previous erysipelas

• Persistent lymphatic damage

• Chronic fungal infection of feet

Clinical Features

Prodrome (hours before skin lesions)

• Fever

• Chills

• Malaise

• Headache

• Vomiting (children)

Local Skin Findings

• Rapidly spreading erythematous plaque

• Raised, sharply demarcated border

• Warm and tender

• Edematous swelling

• Shiny tight skin

• Burning pain

Advanced Local Findings

• Superficial blistering (bullae)

• Petechiae or superficial hemorrhage

• Lymphangitis streaking

• Regional lymphadenopathy

Systemic manifestations

• High fever (38–40°C)

• Tachycardia

• Leukocytosis

• Toxic appearance

Diagnostic Criteria

Diagnosis is primarily clinical.

Major diagnostic features

• Acute onset fever

• Raised well-demarcated erythematous plaque

• Tender swelling

Supportive features

• Regional adenopathy

• Blistering due to edema

• Superficial hemorrhage

Differential Diagnosis

Investigations

Usually not required for uncomplicated erysipelas.

Laboratory tests

Microbiology

• Skin cultures rarely useful

• Aspiration culture occasionally performed in severe disease

Imaging

• Ultrasound: rule out abscess

• Doppler: rule out DVT

• CT/MRI: suspected necrotizing infection

Treatment

A. Non-Pharmacological Management

• Bed rest

• Elevation of affected limb

• Compression therapy after acute phase

• DVT prophylaxis (if immobilized)

B. Local Therapy

• Weak potassium permanganate soaks (0.025%) twice daily

• Reduce bacterial load and exudate

Topical options:

• Silver sulfadiazine cream

• Mupirocin 2%

• Fusidic acid 2%

(Topicals are adjuncts — NOT definitive treatment)

C. Systemic Antibiotic Therapy (Main Treatment)

First-line (Streptococcal coverage)

Phenoxymethylpenicillin

• Adults: 250–500 mg PO every 6 hours × 5–7 days

• Children: 25 mg/kg every 6 hours

OR

Flucloxacillin

• Adults: 500 mg PO every 6 hours × 5–7 days

• Children: 25–50 mg/kg every 6 hours

Severe infection (hospitalized)

• IV benzylpenicillin or ceftriaxone (not listed but clinically standard)

D. Surgical Treatment

Indicated if complications develop:

• Secondary abscess → incision & drainage

• Necrosis → surgical debridement

Complications

Local complications

• Abscess formation

• Skin necrosis

• Ulceration

• Chronic lymphedema

• Recurrent erysipelas

Systemic complications

• Bacteremia

• Septic arthritis

• Endocarditis

• Post-streptococcal glomerulonephritis

• Toxic shock syndrome

Prevention

• Treat tinea pedis aggressively

• Proper wound care

• Control edema (compression stockings)

• Skin moisturization to prevent fissures

• Weight reduction

• Glycemic control in diabetics

Recurrent erysipelas prophylaxis

Long-term penicillin prophylaxis may be required in frequent recurrence.

Patient Education

Seek urgent care if:

• Fever >38.5°C

• Rapid spread of redness

• Severe pain

• Blistering or black discoloration

• Confusion or weakness

Do NOT:

• Massage affected area

• Apply irritant chemicals

• Walk excessively during acute phase

Prognosis