Impetigo contagiosa

Introduction

Impetigo contagiosa is a superficial, highly contagious, bullous skin disorder caused by coagulase positive staphylococci and occasionally -haemolytic streptococci.

Symptoms and Clinical features of impetigo contagiosa

Children are more commonly affected

  1. Initial lesions are superficial vesicles, or bullae found around orifices: eyes, nose and ears
  2. Begins with a 2 mm erythematous macules which quickly develop into vesicles or bullae
    • Blisters are superficial and rupture easily, releasing a thin straw-coloured seropurulent discharge
    • The exudate dries to form loosely stratified golden yellow crusts
  3. Auto-inoculation from fluid (from ruptured blister) leads to multiple lesions
  4. As the lesions spread peripherally and the skin clears centrally, large circles are formed by fusion of the spreading lesions to produce gyrate patterns
  5. Lesions heal without scarring, but may leave behind erythema and hyperpigmentation
  6. Other pruritic dermatoses may become impetiginized (i.e. infected with the above organisms):
    • Scabies
    • PediculosiPapular urticaria
    • Atopic eczema

Differential diagnoses

  • Ringworm
  • Ecthyma
  • Herpes simplex

Complications of impetigo contagiosa

  • Regional lymphadenopathy
  • Cellulitis
  • Rarely: septicaemia
  • Rarely: acute glomerulonephritis, if
    nephritogenic strain of streptococcoci is involved

Investigations

  • Wound swab for bacteriology and sensitivity

Treatment

Treatment objectives

  1. Treat infection
  2. Treat underlying pruritic dermatoses
  3. Prevent complications

Non-drug treatment

  1. Debride crusted lesions with soap and water or desloughing antibacterial agents
  2. Dry weepy lesions with astringent such as potassium permanganate, sodium chloride 0.9% solution, hydrogen perioxide

Drug treatment

Erythromycin

  • Adult and child over 8 years: 250-500 mg orally every 6 hours or 500 mg – 1 g every 12 hours for 5-10 days
  • Child:
    • up to 2 years: 125 mg orally
      every 6 hours;
    • 2 – 8 years: 250 mg every 6 hours

Or:

Co-trimoxazole

  • Adult: 960 mg orally every 12 hours for 5-10 days
  • Child:
    • 6 weeks – 5 months: 120 mg;
    • 6 months -5 years: 240 mg;
    • 6-12 years: 480 mg taken orally every 12 hours for 5-10 days

Supportive measures

  • Debride crusted lesions: Dislodging
    antibacterial agen
  • Avoid auto-inoculation e.g. with fingers, shaving brushes,
    handkerchiefs, or pillow cases
  • Strict personal hygiene
  • Treat underlying skin disease(s)

Notable adverse drug reactions

  • Sulphonamide and co-trimoxazole: fixed drug eruption