Impetigo is a blistering skin infection and is usually caused by Staphylococcus aureus or Streptococcus pyogenes.
What does the rash look like?
The impetigo rash can be bullous (with bullae or fluid-filled lesions larger than 0.5cm) or non-bullous (much more common). In the non-bullous form, there are vesicles. Often, there is golden crusting on top of the rash.
What are the other symptoms?
The rash can be itchy or painful (but not commonly). Pyrexia and lymphadenopathy can occur in severe cases.
How is it diagnosed?
Impetigo is typically diagnosed clinically, but bacterial swabs may be sent if the infection is severe. MRSA may cause resistant infections, so a swab could also be helpful here.
What is the course of the illness?
As the impetigo resolves, the golden crust dries and separates.
What are the possible complications?
Impetigo can spread very easily on contact and often spreads to other sites on the body.
It is also possible to develop post-streptococcal glomerulonephritis.
How long are patients infectious?
Patients are infectious until the crusting has all dried up. They should stay away from childcare until then.
What treatment should I offer?
Treatment is with antibiotics and depends on the extensiveness and resistance of the infection.
Impetigo with localized, superficial infection
Usually, these children are managed with topical antibiotics (mupirocin 2% TDS or fusidic acid 2% TDS) for 5-7 days. They are as effective as oral antibiotics.
Even a localized superficial infection in neonates should be treated with oral antibiotics (erythromycin for seven days) and a dermatologist should be consulted.
Widespread, cutaneous impetigo
One of the following oral antibiotics should be used for 7 days to treat this condition.
Flucloxacillin: 12.5-25 mg/kg QID; adult dose is 250-500mg QID
Erythromycin: 10mg/kg QID; adult dose is 250mg QID
Cephalexin: 25mg/kg QID; adult dose is 250-500mg QID
Localized, superficial impetigo with suspected MRSA infection
If the infection is resistant to the treatment above, or MRSA is suspected, then treatment should be with one of the following antibiotics:
Clindamycin: 5mg/kg QID; dose in adults is 150-450mg QID
Trimethoprim/sulfamethoxazole: 4-5mg/kg BD; adult dose is 160mg BD (dose refers to trimethoprim component)
Impetigo with a deep infection or haematogenous spread
In children with pyrexia or systemic symptoms, IV antibiotics are indicated. Use one of the following antibiotics.
Flucloxacillin: 50mg/kg QID IV (max 2g)
Impetigo with a deep infection or haematogenous spread and suspected MRSA
These patients should be treated with vancomycin.
Vancomycin: 10mg/kg IV QID; adult dose is 500mg IV QID or 1g IV BD
Patients with recurrent infections consider intranasal antibiotics (mupirocin 2% TDS for 7 days) to treat nasal colonization.
Washing with soap and water twice a day is recommended to reduce skin bacteria.
Freeman M, Del Mar C. Impetigo. Best Practice, BMJ
McLinn S. A bacteriologically controlled, randomized study comparing the efficacy of 2% mupirocin ointment (Bactroban) with oral erythromycin in the treatment of patients with impetigo. J Am Acad Dermatol. 1990;22:883-885.