Impetigo is a highly contagious bacterial infection of the skin. Good hygiene helps prevent spread of infection. If antibiotics are given it is important to finish the whole course to make sure the impetigo will not recur.

Last updated: 12 April 2017
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What is impetigo?

Impetigo is a bacterial skin infection caused by Streptococcus and Staphylococcus bacteria. It is commonly known as ‘school sores’ because a majority of cases are in school-aged children. However, it can also affect infants, adults and adolescents.

Uncomplicated impetigo does not cause permanent damage to the skin, but is highly contagious.

What does it look like?

Impetigo occurs in two forms, blistering and crusted. In blistering impetigo the blisters arise on previously normal skin, and rapidly grow in size and number. The blisters quickly burst and leave slightly moist or glazed areas with a brown crust at the edge. The spots expand even after they break open and can be many centimetres wide. They sometimes clear in the centre to produce ring shaped patterns. They are not usually painful, but can be itchy.

Crusted impetigo has a thick soft yellow crust. Beneath this crust is a moist red area. Crusted impetigo spots grow slowly and are always smaller than the fully developed spots of blistering impetigo. They are not usually painful, but can be itchy.

Impetigo can occur on top of other skin conditions, particularly itchy ones. When the skin is scratched the infection can enter through the broken skin. Some of these conditions are atopic dermatitis (eczema), scabies, insect bites and head lice.

In cases where a larger area of skin is affected, patients may also have a fever, swollen lymph nodes or feel generally unwell.

How is it diagnosed?

Your doctor may diagnose impetigo based on a visual inspection of the blisters/ sores, or by taking a swab to test for bacteria and check which antibiotic to use. The result of the swab takes several days.

How is it treated?

Depending on how bad the infection is, your doctor may recommend the use of an antibiotic ointment or oral antibiotics in severe cases. Antibiotic ointment should be continued until the sores have completely healed. If oral antibiotics are given it is important to finish the whole course of treatment (usually 5 days) and not stop when the impetigo starts to clear.

Sores should be cleaned every 8 – 12 hours, dried thoroughly and covered with a waterproof dressing. Bathing the blisters with salty water will help to dry them out (use saline solution or dissolve about half a teaspoon of salt in a cup of water).

How is it spread?

Impetigo is very easy to catch from other people. Impetigo is usually spread through direct contact with other infected people.

The bacteria primarily enter through damaged skin. People with conditions causing long-term damage to their skin, such as eczema or atopic dermatitis, are at greater risk of infection.

How can you avoid spreading the infection?

While you have the infection:

  • ​Sores should be kept clean and covered with a waterproof dressing to prevent them being touched or scratched.
  • Used dressings should be placed in a sealed bag and put in the garbage bin as soon as they are removed.
  • Hands should be washed thoroughly with soap and running water for 10 – 15 seconds after sores are touched or redressed.
  • Children with impetigo should be kept home from school or other group settings if their wounds cannot be kept covered until 24 hours after antibiotic treatment has been started, or until the blisters have dried out if antibiotics are not used.

To prevent impetigo children should be taught:

Parents should be careful not to allow items such as clothes, towels, bed sheets, razors or toothbrushes used by the affected person to be used by others. Other grooming items, such as nail scissors or tweezers, should be disinfected/washed thoroughly after each use.

In addition to general hygiene measures, specific measures to prevent spread in schools and childcare include:

  • teachers, children and families should understand the importance of hand washing, covering sores and staying home if sick
  • hand washing products (soap dispensers, running water and paper towels) should be available and accessible
  • activities should allow time for hand washing as part of routine practice (before eating and after going to the toilet)
  • temporary exclusion from child care or school if their wounds cannot be kept covered until 24 hours after antibiotic treatment has been started, or until the blisters have dried out if antibiotics are not used
  • surfaces such as counters, desks and toys that come in contact with uncovered or poorly covered infections, should be cleaned daily with detergent, and whenever visibly contaminated.

Impetigo is dangerous for babies

It is important for people with impetigo to keep away from newborns and young babies. Newborn babies are particularly susceptible to impetigo because their immune systems are not fully developed.

What is the public health response?

Impetigo is not notifiable in NSW. Public health units can advise on the control of outbreaks.

Group A streptococcal infection may lead to other rare conditions such as acute post-streptococcal glomerulonephritis 3–6 weeks after the skin infection, which is associated with antibodies produced to fight streptococcal infection.

In communities in Australia that have cases of rheumatic heart disease, episodes of acute rheumatic fever are thought to be triggered by impetigo as well as by throat infections with group A Streptococcus. In those communities prompt treatment and control of impetigo is an important part of preventing rheumatic heart disease.

For further information please call your local Public Health Unit on 1300 066 055

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Page Updated: Wednesday 12 April 2017