Impetigo is a highly contagious skin infection that is most likely to affect children aged from 2 to 5 years. The first sign is a patch of red, itchy skin.
In northern Europe, northern America, and Canada, it is the most common bacterial skin infection in children, but it can happen at any age. It is more common where people live in confined environments, such as army barracks, or in warm, humid climates.
Impetigo is rarely serious and usually resolves on its own within 2 weeks. However, complications sometimes occur, so a doctor may prescribe an antibiotic ointment or oral antibiotics.
Fast facts on impetigo
Here are some key points about impetigo. More detail is in the main article.
- Impetigo is a contagious skin infection that is most common in children.
- It is caused by Staphylococcus aureus or Streptococcus pyogenes bacteria
- Symptoms normally go away without treatment, but this depends on the type of impetigo and the severity of symptoms
Treatment for impetigo aims to speed up healing, improve the skin's appearance, and prevent complications and the spread of infection.
The type of treatment will depend on the type of impetigo and the severity of symptoms.
If the infection is mild, a doctor may only recommend keeping the skin clean.
A more severe infection may need treatment with antibiotics.
Topical antibiotics are applied directly onto the skin. The doctor might prescribe a mupirocin ointment, such as Bactroban. Before applying ointment, scabs need to be gently removed so that the antibiotic can get deep into the skin.
It is important to wash affected areas of skin with warm, soapy water before applying a topical antibiotic. If possible, latex gloves should be used when applying the cream. Hands should be washed thoroughly after.
The patient should respond to treatment within 7 days.
A course of antibiotics usually lasts about 7 days. It is important to complete the course, even if symptoms clear up early.
A child can go back to school 24 hours after antibiotic treatment starts, or when the sores have crusted and healed.
The main symptoms of impetigo are red sores that burst and ooze before drying up.
The symptoms will depend on the type of impetigo.
Impetigo is caused by either:
- Staphylococcus aureus (S. aureus)
- Streptococcus pyogenes (S. pyogenes)
S. aureus exists harmlessly on human skin, and S. pyogenes is present in the normal mouth flora. However, they can cause infection when there is a cut or wound.
Infection can start in two ways:
- Primary impetigo: Bacteria invade the normal, healthy skin without a site of entry.
- Secondary impetigo: Bacteria invade the skin because another skin infection or condition has disrupted the skin barrier, such as eczema or scabies.
How do the bacteria enter the skin?
Impetigo in adults usually results from injury to the skin, often from another skin condition, such as dermatitis, an inflammation of the skin.
Children are usually infected after a cut, scrape, or insect bite, but infection may occur without apparent skin damage.
How does it spread?
One person can become infected by touching things that an infected person has been in contact with, such as bed linen, towels, toys, and clothing. Once infected, that person can easily pass it on to other people.
Symptoms do not appear until 4 to 10 days after initial exposure to the bacteria. During those days, people often pass the infection on to others because they do not know they are infected.
Children may be more likely to become infected and show symptoms because their immune systems are not yet fully developed.
When symptoms appear, the individual should stay at home and not return to school or work until the lesions are dry with scabs or until 48 hours after starting antibiotic treatment.
There are two main types of impetigo: Non-bullous and bullous.
Non-bullous impetigo, or impetigo contagiosa
Around 70 percent of cases of impetigo are of this type.
Small red blisters appear around the mouth and nose, or, occasionally, in the extremities. The blisters soon burst and ooze either fluid or pus, leaving thick, yellowish-brownish golden crusts.
As the crusts dry, they leave a red mark which usually heals without scarring.
Although the sores are not painful, they may be very itchy. It is important not to touch or scratch them to prevent the infection from spreading to other parts of the body and other people.
In rare cases, symptoms may be more severe, with a fever and swollen glands.
Bullous impetigo is caused by a certain strain of Staphylococcus aureus that secretes a type of toxin that targets the skin layer. It mainly affects infants under the age of 2 years.
Medium to large-sized fluid-filled blisters appear on the trunk, legs, and arms. The skin around the blister is red and itchy, but not sore. They often spread rapidly and eventually burst, leaving a yellow crust. The crust normally heals with no scarring.
The blisters are not painful, but they may be very itchy. Patients must try not to touch or scratch them.
Fever and swollen glands are common with this type of impetigo.
Impetigo is common among preschool children and those of school age. It can affect the face, neck, hands, and the diaper area.
Damage to skin due to cuts, grazes, or poison ivy rash can allow the infection to enter.
It can easily spread among children. To reduce the risk, encourage children to wash their hands regularly and not to scratch or touch any wound or skin lesion. Keep washcloths, towels, clothing, and bedding separate too.
Children who have any signs of impetigo should see a doctor. If sores are not healing after 3 days of treatment, or if a fever develops, you should return to the doctor.
Impetigo is fairly easy to diagnose by examining the affected area. The doctor will probably ask the patient, parent, or caregiver about any recent cuts, scrapes, or insect bites to the affected area.
They will also try to find out whether it has appeared with another skin condition, such as scabies.
Further tests may be ordered if:
- symptoms are severe and have spread to many parts of the body
- the patient does not respond to treatment
- the infection keeps recurring
The doctor will gently wipe a crusted area with a swab to see which germ is causing the impetigo and which antibiotic is most likely to work. A swab may also help determine whether there is another infection, such as ringworm or shingles.
If the patient has repeated episodes of impetigo, the doctor may take a swab from the nose to determine whether the infective bacteria are based there.
Very rarely, complications can occur. These can be serious. If symptoms become worse, the patient should return to the doctor.
The following complications are possible:
- Cellulitis: If the S. Aureus bacteria multiply and spread into deeper layers of skin, this is no longer impetigo, but a more serious complication, cellulitis. The skin will be red and inflamed, and there will be fever and pain.
- Guttate psoriasis: Red, scaly patches of inflamed skin develop on all parts of the body. It is non-infectious and may occur in children and teenagers after a bacterial infection, especially a throat infection.
- Scarlet fever: This is a rare bacterial infection caused by Streptococcus pyogenes. Symptoms include a fine, pink rash across the body, and possibly nausea, vomiting, and pain.
- Bacteremia or sepsis: A bacterial infection of the blood, leading to fever, possibly rapid breathing, vomiting, confusion, and dizziness. This is a life-threatening infection and requires immediate hospitalization.
- Post-streptococcal glomerulonephritis: An infection of the small blood vessels in the kidneys that can be fatal for adults. This complication of impetigo is very rare. Symptoms include darkened colored urine and hypertension. Hospitalization is usually necessary, to monitor blood pressure.
Good hygiene is the best way to reduce the risk of developing or spreading impetigo. Washing any cuts, scrapes, grazes, and insect bites immediately and keeping them clean will help reduce the risk.
If somebody has impetigo, it is important to keep their belongings isolated from other people and to follow strict hygiene measures.
The following will help prevent the spread of infection to others, and also to other parts of the patient's body:
- washing the affected areas with a neutral soap and running water, then covering the area lightly with gauze
- not touching the sores and discouraging the patient from doing so
- keeping the patient's clothes, bedding, towels, and other toiletries separate, and washing them daily at 60° Celsius (140° Fahrenheit) or higher
- when applying antibiotic ointment, using gloves and washing hands thoroughly afterward
- keeping the patient's nails short to reduce scratching
- ensuring both the caregiver's and the patient's hands are washed often
- isolating the patient until they are not contagious
To prevent a recurrence, make sure any skin condition, such as eczema, is treated properly.