Impetigo

Causes of impetigo

Impetigo occurs when the skin becomes infected with bacteria, usually either Staphylococcus aureus or Streptococcus pyogenes.

The bacteria can infect the skin in 2 main ways:

• through a break in otherwise healthy skin – such as a cut, insect bite or other injury – this is known as primary impetigo
• through skin damaged by another underlying skin condition, such as head lice, scabies or eczema – this is known as secondary impetigo

The bacteria can be spread easily through close contact with someone who has the infection, such as through direct physical contact, or by sharing towels or flannels.

As the condition doesn’t cause any symptoms until 4 to 10 days after initial exposure to the bacteria, it’s often easily spread to others unintentionally.

Children and people with diabetes or a weakened immune system – either due to a condition such as HIV or a treatment such as chemotherapy – are most at risk of developing impetigo.

Impetigo occurs when the skin becomes infected with bacteria, usually either Staphylococcus aureus or Streptococcus pyogenes.

These bacteria can infect the skin in 2 ways:

• through a break in otherwise healthy skin, such as a cut, insect bite or other injury – this is known as primary impetigo
• through skin damaged by another underlying skin condition, such as head lice, scabies or eczema – this is known as secondary impetigo

The bacteria can be spread easily through close contact with someone who has the infection, such as through direct physical contact, or by sharing towels or flannels.

As the condition does not cause any symptoms until 4 to 10 days after initial exposure to the bacteria, it is often easily spread to others unintentionally.

Impetigo stops being infectious after 48 hours of treatment starting or after the sores have stopped blistering or crusting.

Impetigo usually clears up on its own in around 2 to 3 weeks, even without any treatment. Even so, doctors often recommend treating it, because treatment can shorten the illness to about 7 to 10 days and lowers the chance of passing the infection on to someone else.

The main treatments are antibiotic cream or antibiotic tablets, usually used for about a week. If a swab confirms impetigo, it can generally be treated effectively with antibiotics. If an underlying skin condition such as eczema is behind the infection, that will need attention too.

Antibiotic cream

For mild impetigo covering a small area, an antibiotic cream is often the first choice. It is usually applied 3 or 4 times a day for 7 days.

Before applying the cream, wash the affected skin with warm, soapy water and gently clean away any crusts that have formed. Wash your hands right after applying the cream, or wear latex gloves while applying it, to avoid spreading the infection further.

The cream can sometimes cause irritation, redness, or itchiness where it is applied. If there is no improvement after 7 days of treatment, ask your pharmacist about other options.

Antibiotic tablets

Antibiotic tablets may be prescribed if the infection is more severe, covers a wider area, or hasn't improved with cream alone. These are usually taken 2 to 4 times a day for 7 days.

If you or your child are given a course of oral antibiotics, it is important to finish the full course, even if the symptoms clear up before the tablets run out. Common side effects include nausea, vomiting, and diarrhoea. If symptoms haven't improved after 7 days of tablets, speak to your pharmacist.

Further testing and treatment

Further tests are usually only needed if the infection is severe, widespread, not responding to treatment, or keeps coming back. In such cases, your doctor may refer you to a dermatologist, or may take a swab of the affected skin for testing. This can help confirm or rule out other skin conditions and can also check whether you carry the type of bacteria responsible for the infection inside your nose.

If your doctor suspects that you keep getting impetigo because these bacteria live naturally in your nose, they may prescribe an antiseptic nasal cream to help clear them.

Cellulitis

Cellulitis develops when the infection spreads into a deeper layer of skin. It can cause red, inflamed skin along with fever and pain. It is usually treated with antibiotics, and painkillers can help ease the discomfort.

Guttate psoriasis

Guttate psoriasis is a non-infectious skin condition that can develop in children and teenagers after a bacterial infection, most often a throat infection, though some cases have followed impetigo. It causes small, red, droplet-shaped, scaly patches on the chest, arms, legs, and scalp. Creams can help control the symptoms, and in some cases the condition clears up completely within a few weeks.

Scarlet fever

Scarlet fever is a rare bacterial infection that causes a fine, pink rash across the body, often along with nausea, pain, and vomiting. It is usually treated with antibiotics. Scarlet fever isn't usually serious, but it is contagious, so an infected child should be kept away from close contact with others. Keep your child home from school until they have been on antibiotics for at least 24 hours.

Septicaemia

Septicaemia, a type of sepsis, is a bacterial infection of the blood. It can cause diarrhoea, cold and clammy skin, fever, rapid breathing, vomiting, low blood pressure, confusion, faintness or dizziness, and loss of consciousness. Septicaemia is life-threatening and needs immediate antibiotic treatment in hospital.

Scarring

In rare cases, impetigo can leave some scarring, though this usually happens because someone has scratched at the blisters, crusts, or sores rather than from the infection itself. Left alone to heal, the blisters and crusts should not scar. The red mark that remains after the crusts and blisters clear should fade on its own, which can take anywhere from a few days to a few weeks.

Staphylococcal scalded skin syndrome

Staphylococcal scalded skin syndrome, or SSSS, is a serious condition in which the Staphylococcus bacteria behind some cases of impetigo release a toxin that damages the skin. This causes widespread blistering that can look like the skin has been scalded with boiling water. Other symptoms include painful skin, fever, large areas of peeling skin, and redness that often spreads across the whole body. SSSS usually needs immediate hospital treatment with antibiotics given directly into a vein.

Post-streptococcal glomerulonephritis

Post-streptococcal glomerulonephritis is an infection of the small blood vessels in the kidneys and a very rare complication of impetigo. Its symptoms include urine that turns reddish-brown or cola-coloured, swelling of the abdomen, face, eyes, feet, and ankles, a rise in blood pressure, visible blood in the urine, and a drop in the amount of urine produced. People with this condition usually need immediate hospital treatment so their blood pressure can be closely monitored and controlled. It can be fatal in adults, though deaths in children are rare.

Preventing the spread of impetigo

During treatment, it’s important to take precautions to minimise the risk of impetigo spreading to other people or to other areas of the body.

Most people are no longer contagious after 48 hours of treatment or once their sores have dried and healed. It’s important to stay away from work, school, nursery or playgroup until this point.

The advice below can also help to prevent the spread of the infection:

• do not share flannels, sheets or towels with anyone who has impetigo – wash them at a high temperature after use
• wash the sores with soap and water and cover them loosely with a gauze bandage or clothing
• avoid touching or scratching the sores, or letting others touch them – it may help to ensure your nails are kept clean and short
• avoid contact with newborn babies, preparing food, playing contact sports, or going to the gym – until the risk of infection has passed
• wash your hands frequently – particularly after touching infected skin
• washable toys should also be washed – wipe non-washable soft toys thoroughly with a cloth that has been wrung out in detergent and warm water and allowed to dry completely

If you think that the infection has spread to someone else, make sure they’re seen by a pharmacist as soon as possible.

Preventing recurrent impetigo

To reduce the risk of impetigo returning, make sure any cuts, scratches or bites are kept clean. Ensure any condition that causes broken skin, such as eczema, is treated promptly.

If you develop impetigo frequently, your doctor may suggest taking a swab from around your nose to see if you carry staphylococcal bacteria. These bacteria can live in the noses of some people without causing problems, although they can lead to impetigo if they infect broken skin nearby.

If you’re found to carry these bacteria, you may be prescribed an antiseptic nasal cream to apply several times a day for 5 to 10 days in an attempt to clear the bacteria and reduce the chances of impetigo recurring.

Preventing impetigo

As impetigo is a highly contagious condition, it is important to take precautions to reduce the risk of the infection spreading.

Stopping the infection spreading

To help to prevent the spread of the infection to other people or to other areas of the body you should:

• stay away from work, school, nursery or playgroup until the sores have dried up, blistered or crusted over, or until 48 hours after starting treatment
• not share flannels, sheets or towels with anyone who has impetigo, and wash them at a high temperature after use
• wash the sores with soap and water, and cover them loosely with a gauze bandage or clothing if possible
• avoid touching the sores, or letting others touch them, whenever possible
• not scratch the affected areas – it may help to ensure your or your child’s nails are kept clean and short to reduce the risk of further damage caused by scratching
• avoid contact with newborn babies, preparing food, playing contact sports, or going to the gym until the risk of infection has passed (when the rash has crusted over, or after at least 48 hours of treatment with antibiotics)
• wash your hands frequently, particularly after touching infected skin
• washable toys should also be washed, and wipe non-washable soft toys thoroughly with a cloth that has been wrung out in detergent and warm water and allowed to dry completely

If you think that the infection has spread to someone else, make sure they contact their pharmacist as soon as possible.

Preventing re-infection

To reduce the risk of impetigo returning, make sure any cuts, scratches or bites are kept clean, and ensure any condition that causes broken skin, such as eczema, is treated promptly.

If you develop impetigo frequently, your doctor may suggest taking a swab from around your nose to see if you carry staphylococcal bacteria inside your nose. These bacteria can live in the noses of some people without causing problems, although they can lead to impetigo if they infected broken skin nearby.

If you are found to carry these bacteria, you may be prescribed an antiseptic nasal cream to apply several times a day for 5 to 10 days in an attempt to clear the bacteria and reduce the chances of impetigo recurring.

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Complications of impetigo are rare, but they can occur and can sometimes be serious. If you have impetigo and your symptoms change or get worse, tell your pharmacist.

Some complications linked with impetigo include:

• cellulitis, an infection of the deeper layers of the skin and the tissue underneath
• scarlet fever, a rare bacterial infection that causes a fine, pink rash across the body
• guttate psoriasis, a non infectious skin condition that can develop in children and teenagers after a bacterial infection
• septicaemia, a type of sepsis, which is a bacterial infection of the blood
• Staphylococcal scalded skin syndrome, also known as SSSS, a serious skin condition that makes the skin look as though it has been scalded with boiling water
• post streptococcal glomerulonephritis, an infection of the small blood vessels in the kidneys

In very rare cases, impetigo may lead to some scarring, especially if you scratch at the blisters, crusts or sores.

Complications of impetigo are rare, but they can occur and can sometimes be serious. If you have impetigo and your symptoms change or get worse, tell your pharmacist.

Increased risk

Besides the situations mentioned above, several other factors can raise your chances of developing impetigo. These include:

• being a child, since impetigo is thought to be more common in children because their immune system has not yet fully developed, and because they tend to spend time in places where the infection can easily spread, such as schools and nurseries
• having diabetes
• being a carrier of Staphylococcus aureus bacteria, which can live in the noses of some people without causing problems, but can sometimes cause impetigo if they get into damaged skin nearby
• warm and humid weather, since impetigo tends to be more common during the warmer, more humid months, possibly because such weather is a better environment for the bacteria to grow, and because the skin is more likely to be exposed to insect bites and cuts at this time of year
• having a weakened immune system, whether from a condition such as HIV or a treatment such as chemotherapy