Impetigo is a blistering skin infection and is usually caused by Staph. aureus or Strep. pyogenes.
The rash can be itchy or painful (but not commonly). In severe disease it can be associated with pyrexia and lymphadenopathy.
Impetigo is usually diagnosed clinically, but if the infection is severe then bacterial swabs could be sent. Resistant infection may be caused by MRSA so a swab would be helpful in this case too.
As the impetigo resolves, the golden crust dries and separates.
Impetigo can spread very easily on contact and often spreads to other sites on the body.
Cellulitis, osteomyelitis or sepsis can occur, but more commonly in neonates with bullous impetigo.
Post-streptococcal glomerulonephritis is also seen.
Patients are infectious until the crusting has all dried up. They should stay away from childcare until then.
Treatment is with antibiotics and depends on the extensiveness and resistance of the infection.
Impetigo with localised, superficial infection
These children are usually managed with topical antibiotics (mupirocin 2% TDS or fusidic acid 2% TDS) for 5-7 days, which has shown to be as effective as oral antibiotics.
In neonates, even a localised superficial infection should be treated with oral antibiotics (erythromycin for 7 days) and a dermatologist consulted.
Widespread, cutaneous impetigo
This should be treated with one of the following oral antibiotics for 7 days.
- 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
Localised, 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
IV antibiotics are indicated in children with pyrexia or systemic symptoms. 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
In patients with recurrent infections consider intranasal antibiotics (mupirocin 2% TDS for 7 days) to treat nasal colonisation.
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.