DermatologyTier 1Disease (DEADMAN)

Bacterial infections - impetigo

Description

Superficial bacterial skin infection - non-bullous (commonest, golden-crusted lesions) and bullous (flaccid blisters, S. aureus exfoliative toxin) variants

Epidemiology

Common in children, esp. in warm/humid climates and overcrowded living conditions
Highly contagious - spreads via direct contact/fomites, outbreaks in schools/childcare
Disproportionately high burden in remote Aboriginal and Torres Strait Islander communities

Aetiopathogenesis

Staphylococcus aureus and/or Streptococcus pyogenes - superficial epidermal invasion, often through minor skin breaks (insect bites, eczema, scabies infestation)
Bullous variant - exfoliative toxin-producing S. aureus cleaves desmoglein-1 -> superficial blister formation

Diagnosis

Clinical - golden/honey-coloured crusted lesions (non-bullous) or flaccid bullae (bullous), typically face/limbs in children
Swab for culture if extensive/recurrent/treatment failure or outbreak setting (resistance patterns)

Management

Localised, limited disease: topical antiseptic or topical antibiotic (mupirocin)
Widespread/multiple lesions or bullous impetigo: oral flucloxacillin or cephalexin; consider community MRSA cover based on local resistance patterns
Address predisposing skin condition (treat scabies, eczema) and hygiene measures to prevent spread
Exclude from school/childcare until 24h after starting effective treatment or until lesions have crusted over

Associations

Post-streptococcal glomerulonephritis (rare but recognised complication of streptococcal impetigo)
Underlying scabies or eczema as predisposing/complicating factors, especially in high-incidence communities
Recurrent impetigo - consider nasal S. aureus carriage, household contacts

Natural history & complications

Typically resolves within 7-10 days with appropriate treatment
Highly contagious until treated - rapid spread within households/childcare settings if untreated
Recurrent impetigo in endemic communities reflects ongoing environmental/hygiene/scabies co-factors rather than antibiotic failure alone

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