Impetigo - concise ED revision
Overview
Impetigo is a superficial, highly contagious bacterial infection of the epidermis, most commonly seen in children. Diagnosis is usually clinical. Emergency department (ED) management focuses on:
- recognising the clinical form (non‑bullous vs bullous),
- deciding topical versus systemic therapy,
- giving clear infection‑control and exclusion advice,
- identifying when to swab, refer, or admit.
Guideline reference: NICE guideline NG153.
Aetiology and pathogenesis
- Common organisms: Staphylococcus aureus (classically associated with bullous impetigo) and Group A Streptococcus (Streptococcus pyogenes - common in non‑bullous disease). Methicillin‑resistant S. aureus (MRSA) can cause impetigo in settings with increased prevalence or after treatment failure.
- Pathogenesis: bacteria enter via minor breaks in the skin (cuts, insect bites, eczema) and produce a superficial epidermal infection.
- Mechanism of bullae: exfoliative toxins produced by some S. aureus strains cause cleavage in the superficial epidermis, producing flaccid bullae.
Epidemiology
- Predominantly a disease of children, with a peak in toddlers and young schoolchildren.
- Bullous impetigo is more common in infants (< 2 years); non‑bullous impetigo commonly affects 2-5 year olds.