Lower limb cellulitis

Definition and Epidemiology

• Cellulitis is a common bacterial skin infection involving the deeper layers of the skin and subcutaneous tissues.
• Lower limbs are frequently affected.
• Common in all age groups but higher incidence in elderly and immunocompromised individuals.

Pathophysiology

• Typically caused by Streptococcus and Staphylococcus species, including MRSA.
• The bacteria enter through breaks in the skin (cuts, abrasions, ulcers, athlete’s foot).
• Risk factors include skin breaches, lymphoedema, obesity, diabetes, and chronic venous insufficiency.

Clinical Features

• Acute onset of erythema, swelling, warmth, and tenderness of the affected area.
• Systemic symptoms may include fever, chills, and malaise.
• Skin may appear tight, glossy, and blistered in severe cases.
• Lymphangitis and regional lymphadenopathy may be present.

Diagnosis

• Primarily clinical, based on history and examination.
• Laboratory tests (CBC, CRP, ESR) may show raised inflammatory markers.
• Blood cultures and swabs from any open wounds to identify causative organisms, particularly in severe or recurrent cases.

Management

• Mild to Moderate Cases:
  • Oral antibiotics (e.g., flucloxacillin, or erythromycin/clindamycin for penicillin-allergic patients).
  • Elevating the affected limb and analgesia for symptom relief.
• Severe Cases:
  • Intravenous antibiotics (e.g., IV flucloxacillin, or vancomycin in cases of suspected MRSA).
  • Consider hospital admission for systemic symptoms or rapid progression.
• Recurrent Cellulitis:
  • May require prophylactic antibiotics.
  • Address underlying risk factors (e.g., skin care, compression therapy for oedema).

Complications

• Abscess formation, necrotising fasciitis, sepsis.
• Chronic lymphoedema due to damage of lymphatic vessels.
• Recurrent episodes, particularly in individuals with chronic risk factors.

Prognosis

• Generally good with appropriate antibiotic treatment.
• Chronic or recurrent cellulitis may develop in patients with predisposing factors.