Highly contagious superficial epidermal infection of the skin primarily caused by Staphylococcal and Streptococcal bacteria; typically affects children

Aetiology

• Most commonly occurs in infants and school-age children, but can affect individuals of any age
• Causative organism: Staph. aureus +/- Strep. pyogenes

Pathophysiology

• Infective organisms can invade the skin through minor cuts, insect bites, or abrasions, leading to infection
  • Superficial, localised infection immediately below skin surface
• Highly contagious with discharge on the face, scratching due to irritation can aid spread

Clinical features

• Location is usually the face
• Erythematous macule that vesiculates or pustulates
• Superficial erosion with a characteristic golden crust
• Impetigo may be bullous (causing large blisters) or non-bullous (causing sores)

Investigations

• Usually clinical diagnosis
• Bacterial swab for culture and sensitivity may be useful if:
  • The impetigo is extensive or severe
  • MRSA is suspected
  • The impetigo is recurrent or failing to respond to treatment

Management

• 1st line: NICE now recommend hydrogen peroxide 1% cream for 'people who are not systemically unwell or at a high risk of complications'
  • The change was announced in 2020, seems aimed at cutting antibiotic resistance
  • The evidence base shows it is just as effective at treating non-bullous impetigo as a topical antibiotic
• 2nd line: topical antibiotic creams
  • Usually topical fusidic acid, 7 days
  • Topical mupirocin should be used if fusidic acid resistance is suspected
• Extensive or severe: oral flucloxacillin or clarithromycin 500mg QDS + topical fusidic acid