Impetigo is a contagious bacterial infection of the superficial layers of the epidermis.
Impetigo is the most common bacterial skin infection in children. Commonly called school sores.
There are two general types:
Non-bullous Impetigo (impetigo infectiosa) is most common between the ages of 2 and 5 years. It has a predilection for the nares and around the mouth, and also commonly occurs on the extremities at sites of trauma. Impetigo may develop at sites affected by chicken pox, burns, insect bites, abrasions and lacerations. There is usually little or no pain and no constitutional symptoms.
Bullous Impetigo is most commonly an infection of neonates and typically occurs on the trunk and extremities. Flaccid bullae occur which rupture easily. This condition resembles a localised form of Staphylococcal Scalded Skin Syndrome (SSSS).
Staphylococcus aureus and Streptococcus pyogenes (either individually or in combination).
These are relatively uncommon but include:
Post-streptococcal glomerulonephritis – rarely and does not appear to be influenced by antibiotic treatment.
Impetigo often spreads rapidly, and the infection is generally more severe in children suffering atopic dermatitis (and other dermatological conditions).
Lesions typically begin with a single 2-4mm erythematous macule, which rapidly turns into a vesicle or pustule, which ruptures leaving a honey-coloured crusted exudate
Spread to adjacent skin can be rapid
Resolution without scarring is to be expected
Cultures of the lesions are only required if initial treatment has failed. If performed, swabs should be obtained from beneath the lifted edge of a crusted lesion.
Nasal swabs (and occasionally swabs from the axillae and perineum) are helpful in cases of recurrent impetigo to identify nasal (or other) carriage of Staphylococcus aureus
Topical 2% Mupirocin ointment (rather than cream) applied to affected areas TDS (8 hourly) for 7 days is the preferred treatment for limited disease
Oral antibiotics are indicated for more extensive disease and/or if the patient is systemically unwell
Choice of antibiotic should be guided by local sensitivity patterns and the child’s likelihood of tolerating the antibiotic. Options include:
12.5 – 25 mg/kg/dose (depending on severity/extent of disease, to a maximum of 500mg) QID (6 hourly) for 10 days is generally recommended as first line oral therapy, for reasons of palatability
12.5-25 mg/kg/dose (to a maximum of 500mg) QID (6 hourly) for 10 days is a reasonable alternative
If MRSA (known or suspected) or immediate penicillin allergy: 4mg/kg of Trimethoprim component BD (12 hourly) equivalent to 0.5mL/kg of mixture (maximum of 160mg Trimethoprim component per dose)
Benzathine Penicillin (Intramuscular)
If high risk of Acute Rheumatic Fever or Post-Streptococcal Glomerulonephritis: Intramuscular Benzathine Penicillin (refer to Therapeutic Guidelines for dosing) Children living in remote indigenous communities or with previous acute rheumatic fever (ARF) or poststreptococcal glomerulonephritis (PSGN) are at greatest risk
Soap and water cleansing, air-drying whilst at home, use of child’s own face wash towels, importance of hand washing etc
These simple things may not be known by parents and should be reinforced prior to discharge
The use of disinfectant solutions or medicated soaps probably gives no advantage over plain soap and water and drying
In recurrent cases associated with nasal and other site carriage, chlorhexidine body wash may be preferred, as part of a broad eradication regimen – consultation with Microbiology is recommended in this situation
School exclusion is until lesions are healed and crusted over and no longer weeping, or until 24 hours after commencing antibiotic (topical or systemic) treatment
Whilst at school lesions on exposed areas should be covered with a waterproof dressing
Single-room isolation is NOT required for skin infections.
Epps RE. Impetigo in pediatrics. Cutis. 2004 May;73(5 Suppl):25-6.
Koning S, Verhagen AP, van Suijlekom-Smit LW, Morris A, Butler CC, van der Wouden JC. Interventions for impetigo. Cochrane Database Syst Rev. 2004;(2):CD003261.
Communicable Disease Guidelines for teachers, child care workers, local government authorities, and medical practitioners. 2002 Edition. WA Health Department. www.population.health.wa.gov.au/Communicable/resources/2101%20Comm%20Diseases.pdf
Staying Healthy in Child Care – Preventing infectious diseases in child care – Third Edition. 2003. National Health and Medical Research Council (NHMRC) www.nhmrc.gov.au/publications/synopses/ch40syn.htm