Impetigo

Definition

Impetigo is a contagious bacterial skin infection, commonly occurring in children. It typically presents as superficial lesions that form crusts or blisters. There are two main subtypes:

• Crusted (Non-Bullous): Yellow crusts, generally itchy rather than painful.

• Bullous: Larger, flaccid blisters that erode rapidly, usually Staphylococcus aureus.

Aetiology

• Non-Endemic Regions: Primarily Staphylococcus aureus

• Endemic Regions (e.g. Northern Australia): Streptococcus pyogenes can predominate, even if S. aureus is present

• Mixed infection (Staph + Strep) can occur, especially in hot/humid conditions or crowded living.

Symptoms

• Honey-Yellow Crusting: Classic sign, often linked with staphylococcal infection

• Crusts/Ulceration: May indicate a streptococcal component

• Usually superficial but can have mild tenderness or itching.

Differential Diagnosis

• Pemphigus Foliaceus: Autoimmune superficial bullous disease

• Pemphigus Vulgaris: Deeper blistering, often mucosal involvement

• Folliculitis: Localised pustules around hair follicles

• Herpes Simplex Virus: Typically painful vesicles/ulcers, can have recurrent pattern

Management

General Measures

• Handwashing: Regular, thorough washing to prevent spread

• Antiseptics: (e.g. chlorhexidine washes) may help reduce bacterial load

• Avoid Sharing Towels/Clothing: Minimises cross-infection

• Bleach Baths: Occasionally recommended in persistent or recurrent impetigo; follow local guidelines

• Crust Removal: Soften with saline or warm water compresses, gently remove crust for topical treatment penetration

• Infection Control: Keep lesions covered if possible, exclude from childcare/school until appropriate treatment started (check local public health guidelines)

Pharmacological Treatment

• Mild/Localised:

  • Topical Mupirocin TDS for ~5 days; re-evaluate if no improvement

• Extensive or Severe:

  • Oral Flucloxacillin (covers staphylococci, some streptococci) 500 mg QID for 5–7 days (child dosing by weight)

  • Consider oral cephalexin if penicillin-allergic (non-immediate) or for strep coverage in endemic areas

• Swabs: For severe or non-responsive cases to guide targeted antibiotic therapy

Notes

• Reinforce school/daycare exclusion policies: Typically exclude until 24 hours of antibiotic therapy commenced and sores are covered.

• If persistent or complicated impetigo, check for underlying predisposing factors (e.g. scabies, atopic dermatitis, crowded living conditions).

• Seek specialist advice if MRSA or resistant strains are suspected.