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What causes impetigo?

Staphylococcus aureus and streptococcus pyogenes, or methicillin-resistant staphylococcus aureus (MRSA) bacteria are the usual causes of impetigo. The outer layer of your skin can become infected with this bacteria, resulting in the sores or blisters.

The bacteria can live on your skin and do you no harm, but sometimes, such as when the skin is broken, or if your immune system is low, the bacteria can lead to impetigo.

Impetigo is usually categorised in two ways:

  • Primary impetigo – where the infection affects healthy skin.
  • Secondary impetigo - this is when impetigo bacteria gets into skin that has been damaged by another condition, such as scabies or eczema or if it gets into a break in the skin, such as a scratch, cut or insect bite.

Spreading impetigo

The condition does not cause any symptoms at first, which means it is very easily spread between people. Direct physical contact, or sharing items such as towels, toys, bathwater or utensils is a common way the infection is spread.

It is essential to maintain good hygiene practices, such as washing your hands regularly, to prevent the spread of impetigo. This is particularly important if children are involved – make sure you wash their clothes, bedding, towels and even their toys to help prevent the bacteria spreading.

There are a number of things that can increase the chances of the infection spreading:

  • Humid conditions – the bacteria thrive in hot, humid conditions, which is why it is often spread in places like gym changing rooms or swimming pools. This also means it is more common in the summer months.
  • Crowded conditions - living or working in close proximity with other people can cause bacteria to spread more easily. It’s common in nurseries and schools too, for this reason.
  • Contact sports - sports that involve possible skin-to-skin contact, such as rugby, can increase contact with impetigo-causing bacteria.
  • If you have diabetes you are more likely to develop impetigo.
  • If you have a weakened immune system, you are also more likely to develop the condition.

It is recommended that you seek treatment for impetigo to speed up the recovery time, although it can go away on its own. Treatment also helps prevent it being spread to others. You can find out more about the way that impetigo is treated.

Other conditions that can cause impetigo

Underlying conditions can sometimes lead to secondary impetigo, including head lice, eczema or other skin conditions that leave open sores on your skin, where the bacteria can get in. If the impetigo was caused by something else, this will also need to be treated. A doctor will be able to recommend a treatment for this as well as the impetigo.

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