Impetigo

Published by Bupa's Health Information Team, March 2010.

This factsheet is for people who have impetigo, or who would like information about it.

Impetigo is a skin infection caused by the bacterium Staphylococcus aureus or Streptococcus pyogenes. Impetigo causes fluid-filled spots or blisters that become crusty yellow sores. Impetigo infection usually occurs on the face around the mouth and nose. It is usually treated with antibiotics.

About impetigo

Impetigo is highly contagious and easily spreads from person to person by touch.

Impetigo is most common in children between the ages of two and six. About one in 35 children under four develop impetigo. It's the third most frequent skin condition, after eczema and viral warts.

Symptoms of impetigo

Impetigo infection starts with the appearance of small fluid-filled spots. These burst and then crust over and turn yellow. More spots may develop on skin close to the initial infection. The spots eventually dry out and the scabs fall off to leave red marks, which gradually disappear without scarring.

There are two types of impetigo.

Bullous impetigo is where the fluid-filled spots are often large in size, don't burst easily and tend to last for a few days. They usually occur on your chest, back and abdominal area and in folds of skin such as the nappy area, neck or underarm.

         
                                                            Bullous impetigo

Non-bullous impetigo is where the fluid-filled spots are often small and last only a day or two. They usually occur on your face around the nose or mouth or limbs.

         
                                                        Non-bullous impetigo

Impetigo can sometimes be painful or itchy and may cause swelling in lymph nodes (glands in your body that make up part of the immune system) near the affected area.

Complications of impetigo

Complications of impetigo are uncommon and are more likely to occur if you have bullous impetigo. If impetigo infection spreads to other areas of the body, you could develop the following.

• Skin infection (cellulitis) - the impetigo infection spreads into the lower layers of the skin, causing pain, redness and swelling.
  
• Blood poisoning (septicaemia) - rarely, impetigo infection spreads beyond the skin into the bloodstream and causes a serious infection that needs emergency medical treatment.
  
• Kidney infection (glomerulonephritis) - rarely, the immune response to the impetigo infection can cause kidney problems.
  
• Scarlet fever - impetigo infection may cause a sore throat, fever and reddened skin.
  
• Psoriasis - impetigo infection can cause dry scaly patches on the skin.

Causes of impetigo

Impetigo is usually caused by the bacterium Staphylococcus aureus and less commonly by the bacterium Streptococcus pyogenes.

Impetigo is very contagious and can spread to other people very easily. This can happen either through direct skin to skin contact, or from sharing towels, face flannels or even bathwater.

The spots or blisters usually appear four to 10 days after you first come into contact with the bacteria. If it develops in healthy skin it's called primary impetigo.

Sometimes impetigo starts in an area of broken skin, for example, at the site of a wound, or an area affected by another condition that breaks the skin, such as eczema, scabies or head lice. This is called secondary impetigo.

You are more likely to develop impetigo if you have:

• poor personal hygiene
  
• diabetes mellitus
  
• a weakened immune system, for example if you have HIV/AIDS

Diagnosis of impetigo

If you think you or your child has impetigo you should see your GP. It's usually straightforward to diagnose impetigo from the typical look of the affected skin.

However, impetigo can sometimes be confused with other skin conditions such as shingles, fungal skin infections or cold sores. If there is any doubt, your GP might take a swab from the affected area. The swab will be tested for impetigo at a laboratory.

Treatment of impetigo

Impetigo is usually treated with antibiotics. If only a small area is infected, you may be prescribed a cream or antiseptic ointment. Your GP will probably prescribe an antibiotic cream called fusidic acid, but there are other antibiotics that can be used. This will clear up most impetigo infections in seven days.

You will need to wash the affected area with warm soapy water or with a mixture of half a cup of white vinegar in a litre of warm water before applying the treatment. If it's not too painful try to remove crusty areas before applying the cream or ointment.

Your GP may prescribe a course of antibiotic tablets such as flucloxacillin or erythromycin if the impetigo infection doesn't clear or is already or becoming widespread.

If the infection keeps coming back the bacteria responsible may be living in your nose. Your GP may prescribe a nasal ointment to try to clear the bacteria from your nostrils.

It's important that you finish your course of antibiotics. Always ask your GP for advice and read the patient information leaflet that comes with your medicine.

You must contact your GP if the impetigo infection doesn't clear up after you have completed your treatment or if the condition worsens.

Prevention of impetigo

Impetigo is highly contagious, so it's important to take steps to stop it spreading between family members and other people you come into contact with. There are a number of measures you can take to stop it from spreading.

• Wash your hands frequently.
  
• Don't share towels, flannels, bath soap or bathwater.
  
• Wash towels and sheets at a very high temperature.
  
• Don't touch or scratch the sores and keep your fingernails short.
  
• Clean the affected area gently with soapy water.
  
• Wash your hands before and after putting on the antibiotic cream.
  
• Cover the affected area.

If the sores are on your fingers or hands don't prepare any food until 48 hours after starting treatment.

If you have sores on the mouth, nose or hands don't touch newborn babies.

If your child has impetigo, don't send him or her to school or nursery while the sores are crusted or weeping.

If you have damaged skin or a cut, keep it covered with a waterproof dressing. Always wash your hands before and after changing the dressing. Keep any cuts and grazes clean.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.