Impetigo (school sores)

Notification requirement for impetigo

Impetigo is not a notifiable condition in Victoria. Notification is not required.

Primary school and children’s services centres exclusion for impetigo

Children with impetigo must not attend primary school and children’s service centres until appropriate antibiotic treatment has commenced.

For more information, see the School exclusion table.

Infectious agent of impetigo

Impetigo is caused by strains of Staphylococcus aureus and, less commonly, Streptococcus pyogenes. Some infections can be caused by methicillin-resistant Staphylococcus aureus (MRSA).

Identification of impetigo

Clinical features

Impetigo is a highly contagious bacterial skin infection characterised by skin lesions or sores that form rashes, blisters and crusts or scabs. It most commonly affects infants and young children, but people of all ages can be affected.

It can present as non-bullous or bullous forms:

• Non-bullous impetigo usually starts as small, flat macules that progress into fluid-filled pustules or vesicles. They burst or leak serous fluid to form honey-coloured crusts or scabs.
• Bullous impetigo usually starts as superficial, fluid-filled, thin roofed blisters that burst and leak serous fluid. They may leave scaled rims around the blisters.

Impetigo can spread rapidly to other areas of the body through autoinoculation. It can be associated with skin erythema and itch. Other symptoms can include fever, lymphadenopathy and feeling systemically unwell.

The most commonly affected areas are the mouth, nose, arms, legs and trunk but any part of the body can be affected.

Impetigo usually resolves within several days to weeks. Sometimes after healing, the sores can lead to skin discolouration or, less commonly, scarring.

Complications are rare but can potentially include serious infections such as cellulitis, lymphangitis and bacteraemia.

Staphylococcus aureus can rarely result in ‘scalded skin syndrome’, a serious illness that varies from diffuse scarlatiniform erythema to generalised bullous desquamation of the skin. Impetigo in the neonate often follows Staphylococcus aureus colonisation of the nose, umbilicus, rectum or conjunctivae. It is more commonly associated with bullous impetigo, which often affects the perianal, or nappy, areas.

Streptococcus pyogenes can cause other conditions such as scarlet fever and, less commonly, complications such as acute rheumatic fever, rheumatic heart disease and post-streptococcal glomerulonephritis. Skin infections with Streptococcus pyogenes may be an important risk factor for these complicationsindependent of throat carriage.

Diagnosis

Impetigo is usually diagnosed clinically.

A skin swab for culture and sensitivity testing may be beneficial, especially if the impetigo is widespread, recurrent or not responding to empiric treatment, if there is concern for MRSA infection or if the diagnosis is uncertain.

A nasal swab should be carried out in recurrent infection to identify nasal carriage of Staphylococcus bacteria.

Incubation period of impetigo organisms

The incubation period for impetigo is estimated to vary based on the organism, of 4 to 10 days for Staphylococcus aureus and 1 to 3 days for Streptococcus pyogenes.

Reservoir of impetigo organisms

Staphylococcus aureus and Streptococcus pyogenes are found on humans.

Mode of transmission of impetigo

The bacteria that cause impetigo enter damaged skin, such as cuts, bites and abrasions or skin conditions such as eczema, to cause infection.

It is highly contagious and is transmitted from person to person through direct contact with impetigo lesions, fluid from lesions or contaminated objects and surfaces such as clothing, sheets and linen. Some people can be asymptomatic carriers of bacteria and spread infection. Nasal carriage is particularly likely to transmit disease.

Impetigo can be classified as:

• primary impetigo when it occurs in intact skin
• secondary impetigo when it occurs in damaged skin, such as cuts, abrasions, burns and insect bites, or by a skin condition, such as eczema or dermatitis.

Period of communicability of impetigo

Most people with impetigo are no longer infectious after 24 hours of appropriate antibiotic treatment has commenced.

It is important to keep impetigo skin lesions covered until they are healed to help prevent the spread of infection to other parts of the body or other people.

Susceptibility and resistance to impetigo

While people of all aged can be affected by impetigo, it most commonly affects young children in schools and childcare centres.

People with conditions that cause damage to the skin, such as eczema or atopic dermatitis, or immunocompromising conditions may be at greater risk of impetigo.

Impetigo can be potentially life-threatening in babies and young infants.

Public health significance and occurrence of impetigo

Impetigo is common and occurs worldwide. It rapidly spreads and is highly contagious through direct contact with skin sores and contaminated objects and surfaces. It most frequently occurs in young children in settings such as schools and childcare centres. Predisposing factors also include crowded environments and poor hygiene conditions.

Control measures for impetigo

Preventive measures

Ways to prevent impetigo include the following:

• Avoid direct contact with people with impetigo or sharing personal items with them such as clothing, towels and linen
• Keep skin wounds clean and covered
• Treat pre-existing skin conditions
• Maintain good hand washing and personal hygiene practices.

Control of case

General measures to manage impetigo skin lesions include the following:

• use and complete the antibiotics as instructed by the doctor or pharmacy
• wash the skin lesions with soap and water every 8 to 12 hours
• gently soak, soften and remove any visible crusts
• after each wash, pat the skin lesions dry using a clean towel
• keep the skin lesions clean and covered with a waterproof dressing until healed
• use a crepe bandage if necessary to keep the dressing in place or to prevent touching or scratching the lesions.

Antibiotic treatment may be recommended for impetigo:

• the choice and form of agent depend on the severity of disease, risk of serious illness or complications and the person’s hypersensitivity to antibiotic agents
• antibiotic ointment may be recommended for limited non-bullous impetigo
• oral antibiotics are usually recommended for people with extensive, recurrent or bullous impetigo.

Refer to relevant clinical guidelines, such as the Therapeutical Guidelines, or local infectious diseases services for advice on antibiotic treatment, as required.

General measures to prevent the spread of impetigo include the following:

• avoid touching or scratching skin lesions and keep fingernails short and clean
• keep the skin lesions clean and covered with a waterproof dressing until healed
• wash your hands with soap and water before and after touching, cleaning or applying treatment on the skin lesions
• dispose of used dressings immediately after they are removed
• avoid sharing clothing, towels, bed linen or toiletries
• avoid bathing children in the same bathwater if any child has impetigo
• wash clothes, sheets, towels and utensils that have been used by someone with impetigo every day, ideally in hot water

Children with impetigo must stay at home from school or children’s services, such childcare centres and kindergarten, until antibiotic treatment has been started. All sores on exposed areas of the body must be covered with a waterproof dressing when returning.

Control of contacts

Advice to household or people who live in close quarters include the following:

• educate them about impetigo and the mode of transmission
• avoid contact with skin lesions and fluid from the lesions
• avoid touching or sharing contaminated objects and surfaces such as clothing, towels, bed linen or toiletries used by someone with impetigo
• regularly wash hands with soap and water, particularly after touching skin lesions
• if symptoms of impetigo develop, seek medical care.

Outbreak measures for impetigo

Measures to prevent and manage impetigo in schools and childcare settings:

Children with impetigo must stay at home from school or children’s services, such childcare centres and kindergarten, until antibiotic treatment has been started. All sores on exposed areas of the body must be covered with a waterproof dressing when returning.

• educate staff, parents and children about the importance of hand washing, covering skin lesions and staying home if unwell
• when children return after commencing treatment, ensure skin lesions on exposed areas of the skin are covered with a waterproof dressing, where possible
• advise staff and parents who may have had direct contact with impetigo skin lesions to monitor for symptoms and signs of impetigo and seek medical care if they develop
• clean and disinfect any commonly used or shared objects and surfaces, such as equipment, desks and toys
• encourage children not to share personal items such as clothes, towels, bed linen, drink bottles or utensils.

Resources on preventing infectious diseases in childcare settings can be found on the Staying Healthy: Preventing infectious diseases in early childhood education and care serviceswebpage.

Measures to prevent and manage impetigo in hospitals or maternity wards:

• trace and determine source of infection
• consider examining staff for active lesions anywhere on the body or obtaining nasal swabs from staff to detect asymptomatic carriers, and treating accordingly.
• cohort cases and contacts until all have been discharged. Wherever possible, staff working with colonised infants should not work with non-colonised newborns.
• promote the need for good handwashing and hygiene practices among staff and visitors to the unit where the outbreak has occurred.
• review infection prevention and control procedures and the availability of handwashing facilities, including alcohol-based hand rubs.

Resources on preventing and controlling infection in healthcare settings can be found at the Australian Commission on Safety and Quality in Health Care website.