Introduction & module overview

Skin conditions such as impetigo are common reasons for people to seek advice and treatment from a pharmacist. 

Most impetigo cases are uncomplicated but highly infectious. They can be managed more often than not with a short course of topical hydrogen peroxide cream or a topical antibiotic. Only more severe or complicated cases will require oral antibiotic treatment.

It is important to be able to apply established diagnostic criteria to distinguish between cases that need no treatment, those that require topical or oral antibiotic treatment under a PGD, and those that require onward referral. 

There are two forms of impetigo – bullous and non-bullous. This module and the corresponding Pharmacy First PGDs deal exclusively with the more common non-bullous impetigo. 

Impetigo is caused by a bacterial infection on the surface of the skin. It is most common in young children (two to five years of age), but adults can also be affected. Although it can look dramatic, it is often only mildly itchy, if at all. 

The most common causative organism is Staphylococcus aureus. After exposure to the organism the incubation period is four to 10 days.

Impetigo is highly contagious and there may be a history of contact with other individuals with the same condition.

Clinical findings

Impetigo starts as a small, thin-walled vesicle that bursts quickly leaving an exudate that dries to form a thick yellowish (honey-coloured) or brown crust – often described as looking like “stuck-on cornflakes". 

Lesions typically appear on the face, round the mouth or nose, but can also occur elsewhere on the body (e.g. axillae and trunk). Lesions often occur in clusters and can coalesce. Satellite lesions can develop as a result of autoinoculation from scratching or touching the original lesions.

The crusts dry and heal without scarring over two to three weeks. There may be residual redness that fades over days or weeks. If there is damaged skin (e.g. due to eczema, scabies, insect bites (including head lice), impetigo may become more widespread as the damaged skin provides a portal for entry of bacteria. 

Systemic symptoms are usually absent. Patients do not have sore throat but may have regional lymphadenopathy. There is usually little or no evidence of deep-seated infection (e.g. inflammation, swelling and redness).

Bacterial culture is not routinely required unless there is recurrent or poorly-responsive infection or methicillin-resistant Staphylococcus aureus (MRSA) is suspected. The main risk factors for impetigo are young age (under five years), contact with other cases, and crowded living or work conditions.