Doctors Revision

Dermatology (Skin Conditions)

Cellulitis / Erysipelas

Acute bacterial infection spreading through the dermis and subcutaneous tissues. Erysipelas is a more superficial form with sharply demarcated, raised borders, typically caused by Streptococcus pyogenes. Cellulitis involves deeper tissues, borders are less distinct, often caused by Staph aureus or Strep pyogenes.

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Referral and warning signs

When to refer

Refer to Hospital (HC4/H) for: Severe cellulitis (systemic toxicity, rapid progression, extensive area). Facial or orbital/periorbital cellulitis. Immunocompromised host. Failure of outpatient oral antibiotic therapy. Suspected necrotizing fasciitis (SURGICAL EMERGENCY). Suspected underlying abscess or osteomyelitis.

Red flags

  • Signs of systemic sepsis (hypotension, tachycardia, confusion).
  • Rapid progression of erythema.
  • Severe pain out of proportion to clinical findings.
  • Skin necrosis, bullae, or crepitus (gas).
  • Violaceous (purplish) discoloration.
  • Facial involvement with orbital signs (proptosis, ophthalmoplegia).
  • Immunocompromised patient.

Signs and symptoms

  • Area of skin redness (erythema), warmth, swelling, and tenderness.
  • Erysipelas: Sharply demarcated, raised, bright red plaque, often on face or lower legs. May have preceding fever/chills.
  • Cellulitis: Less distinct borders, redness/swelling spreads more diffusely. May involve deeper tissues.
  • Pain.
  • Skin may appear tense, shiny.
  • Blistering (bullae) or skin necrosis may occur in severe cases.
  • Lymphangitis (red streaks tracking proximally).
  • Regional lymphadenopathy (swollen lymph nodes).
  • Systemic symptoms: Fever, chills, malaise.

Risk factors

  • Skin barrier disruption: Trauma (cuts, abrasions, bites), Ulcers (leg ulcers), Fissures (tinea pedis), Surgical wounds, Dermatitis.
  • Lymphoedema (chronic swelling).
  • Venous insufficiency.
  • Obesity.
  • Diabetes Mellitus.
  • Immunosuppression.
  • Previous episodes of cellulitis.
  • IV drug use.

Diagnosis

Clinical assessment

Diagnosis based on clinical presentation of spreading erythema, warmth, swelling, and tenderness.

Differential diagnosis

  • Deep Vein Thrombosis (DVT) (leg swelling, pain, but usually no distinct erythema/warmth, Wells score).
  • Stasis Dermatitis (chronic venous changes, often bilateral, itchy, may have secondary infection).
  • Contact Dermatitis (itchy, may blister, follows pattern of contact).
  • Erythema Nodosum (tender subcutaneous nodules, usually shins).
  • Necrotizing Fasciitis (severe pain out of proportion, crepitus, rapidly progressing necrosis, systemic toxicity - EMERGENCY).
  • Fixed Drug Eruption.
  • Insect bite reaction.
  • Acute Osteomyelitis (underlying bone pain/tenderness).
  • Septic Arthritis (joint involvement).

Investigations

  • Usually clinical diagnosis.
  • Marking border of erythema with pen can help monitor progression.
  • Full Blood Count (FBC): Leucocytosis common.
  • Blood Cultures: Low yield unless patient systemically unwell/septic.
  • Aspiration/Biopsy of leading edge: Low yield, rarely done.
  • Imaging (Ultrasound, X-ray, CT/MRI): If underlying collection (abscess) or osteomyelitis suspected, or to rule out DVT.

Diagnostic criteria

Clinical diagnosis based on characteristic skin findings and systemic signs.

Management

Non-pharmacological management

  • Elevation of the affected limb to reduce oedema.
  • Rest.
  • Analgesia.
  • Hydration.
  • Treat underlying portal of entry (e.g., tinea pedis, ulcer care).
  • Compression therapy (after acute infection resolves, if underlying venous insufficiency/lymphoedema).

Pharmacological treatment

  • Antibiotics (Target Strep pyogenes +/- Staph aureus):
  • - Mild/Moderate Cellulitis (Outpatient):
  • - Cloxacillin 250-500 mg PO QID (before food) for 7-10 days. (Child: 12.5-25 mg/kg/dose). (LOC: HC3)
  • - OR Amoxicillin/Clavulanate.
  • - OR Cephalexin.
  • - Alternative (Penicillin Allergy): Erythromycin 500 mg PO QID (Child: 7.5-12.5 mg/kg/dose) OR Clindamycin.
  • - Severe Cellulitis (Systemic signs, rapid spread, comorbidities, facial involvement, immunocompromised): Hospital Admission.
  • - IV Antibiotics:
  • - Ceftriaxone 1-2 g IV OD. (Child: 50-80 mg/kg OD). (LOC: HC4/H) - UCG recommends 1g Q12H for 3 days then oral.
  • - OR Cloxacillin IV.
  • - OR Benzylpenicillin IV + Cloxacillin IV.
  • - Consider adding Clindamycin or Vancomycin if MRSA or severe infection/necrosis suspected.
  • - Switch to oral therapy once improving to complete 7-14 day course.
  • Analgesia: Paracetamol, NSAIDs.

Monitoring

Monitor clinical response (erythema border, swelling, pain, fever). Expect improvement within 48-72 hours. If worsening or no improvement, reassess diagnosis and antibiotic choice, consider referral/investigation for complications.

Complications

  • Abscess formation.
  • Necrotizing fasciitis (rare but life-threatening).
  • Sepsis.
  • Lymphangitis / Lymphoedema (can become chronic after recurrent episodes).
  • Thrombophlebitis / DVT.
  • Post-streptococcal glomerulonephritis (rare).

Prevention

  • Good skin care, especially in patients with oedema or venous insufficiency.
  • Prompt treatment of skin breaks, ulcers, tinea pedis.
  • Compression stockings for venous insufficiency/lymphoedema.
  • Prophylactic antibiotics may be considered for recurrent episodes (specialist advice).

Patient education

  • Explanation of cellulitis as a skin infection.
  • Importance of completing the full course of antibiotics.
  • Need for limb elevation and rest.
  • How to monitor for worsening signs.
  • Care for any underlying skin breaks.
  • Prevention strategies for recurrence.

Uganda-specific notes

Common, often related to minor trauma or underlying conditions like lymphoedema (e.g., post-podoconiosis). Differentiating from DVT clinically important. Cloxacillin or Ceftriaxone are common antibiotic choices.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 22, Section 22.1.3

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