Impetigo is a common infection of the superficial layers of the skin, usually caused by Staphylococcus aureus (S. aureus), and less commonly by Streptococcus pyogenes. Impetigo caused by methicillin-resistant Staphylococcus aureus (MRSA) is increasingly prevalent. Impetigo most commonly affects young children. Risk factors for the skin condition include skin trauma or pre-existing skin disease, such as eczema, head lice or scabies; hot or humid weather; poor hygiene; and crowded living conditions.

Impetigo can be bullous or non-bullous, with the latter accounting for approximately 70 per cent of cases. The characteristic lesions usually form around the nose and mouth, starting as small vesicles or pustules and quickly bursting to form yellow or brownish crusted, weeping plaques. Some textbooks describe this as “the golden crust”, others suggest the lesions look like “stuck-on cornflakes”. The infection can spread to other areas of the body, such as the flexures, trunk and limbs.

The condition normally heals without scarring, but it is contagious and often spreads rapidly in nurseries and playgroups, as the fluid from the weeping lesions is highly infectious. The incubation period is four to 10 days so children should be kept at home until scabs have formed over the lesions to minimise the spread of infection.