Impetigo (also called Infantigo) is a highly contagious skin infection that most commonly affects children.
In northern Europe, northern America, and Canada, impetigo is the most common bacterial skin infection in children. The first sign of impetigo is a patch of red, itchy skin.
Children aged 2-5 years are the most likely to develop impetigo. However, people of all ages can be affected. Impetigo 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 a couple of weeks. However, doctors may decide to treat children with an antibiotic ointment or oral antibiotics to prevent complications, which may sometimes occur.
Fast facts on impetigo
Here are some key points about impetigo. More detail and supporting information is in the main article.
- Impetigo is an extremely contagious skin infection; it is most common in children
- Impetigo is caused by Staphylococcus aureus or Streptococcus pyogenes bacteria
- It is the most common childhood bacterial skin infection in northern Europe, northern USA, and Canada
- Treatment will depend on the type of impetigo and the severity of symptoms
Symptoms of impetigo
There are two main types of impetigo:
Non-bullous impetigo (Impetigo contagiosa)
Impetigo is most often caused caused by Staphylococcus aureus.
Red sores appear around the mouth and nose, (occasionally they start in the extremities).
The sores 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 any scarring.
Although the sores are not painful, they may itch a great deal. It is important not to touch or scratch them so that the infection does not spread to other parts of the body and other people.
In rare cases, symptoms may be more severe, and the patient may have a fever and swollen glands.
Non-bullous impetigo (Impetigo contagiosa) - accounts for approximately 70 percent of all cases
Bullous impetigo mainly affects babies and children under the age of 2. 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.
Although the blisters are not painful, they may itch a lot. Patients must try not to touch or scratch them.
Fever and swollen glands are common in patients with bullous impetigo. This type of impetigo is caused by a certain strain of Staphylococcus aureus that secretes a type of toxin that targets the skin layer.
Causes of impetigo
Impetigo is caused by two types of bacteria:
- Staphylococcus aureus
- Streptococcus pyogenes
Both types of bacteria exist harmlessly on human skin. They cause infection when there is a cut or wound. Impetigo in adults is usually the result of injury to the skin - commonly by another skin condition, such as dermatitis (inflammation of the skin).
Children are usually infected after a cut, scrape, or insect bite. However, children may also become infected without any apparent skin damage.
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.
Staphylococcus aureus produces a toxin that causes impetigo to spread to nearby skin. The toxin attacks a protein that helps keep skin cells bound together. As soon as this protein is damaged, the bacteria can spread rapidly.
There are two ways the infection can start:
- Primary impetigo - bacteria invade the skin through a cut, insect bite, or other lesion on normal skin
- Secondary impetigo - bacteria invade the skin because another skin infection or condition has disrupted the skin barrier, such as eczema or scabies
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.
Experts say children are more likely to become infected and show symptoms because their immune systems are not yet fully developed.
Secondary impetigo can occur when bacteria invade the skin after another infection or condition has disrupted the skin barrier.
Impetigo is fairly easy to diagnose by examining the affected area. The doctor will probably ask the patient (or parent) about any recent cuts, scrapes, or insect bites to the affected area.
The doctor will also try to find out whether it has appeared on top of another skin condition, such as scabies.
Further tests may be ordered if:
- Symptoms are very 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 another infection is present, like 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.
Treatments for impetigo
The aim of treatment is to speed up healing, improve the skin's appearance, and prevent complications and the spread of infection. Treatment will depend on the type of impetigo and the severity of symptoms.
A doctor may just opt for hygienic measures; this means keeping the skin clean.
Antibiotics are applied directly onto the skin. The doctor might prescribe mupirocin ointment (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 afterward.
The patient should respond to treatment within 7 days.
These are prescribed when the impetigo is more widespread or if the patient has not responded to topical antibiotics. The type of antibiotic depends on the severity and infection, as well as other factors, including the patient's medical condition and whether they have any allergies.
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 started, or when the sores have crusted and healed.
Complications of impetigo
Although complications with impetigo are rare, they can be serious.
On the very rare occasions that complications do occur, they can be serious. Any parent who sees worsening symptoms in their child should tell their doctor straight away.
- Cellulitis - when the infection goes into a deeper layer of skin, cellulitis can occur, causing symptoms including red, inflamed skin, fever, and pain.
- Guttate psoriasis - a type of psoriasis characterized by red, scaly patches of inflamed skin 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 - a rare bacterial infection caused by Streptococcus pyogenes and characterized by a fine pink rash across the body. The patient may also have nausea, vomiting, and pain.
- Bacteremia or sepsis - a bacterial infection of the blood. The patient will have a fever, possibly rapid breathing and 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. Patients will usually have to be hospitalized so that their blood pressure can be monitored.
Prevention of impetigo
Good hygiene is the best way to reduce the risk of developing or spreading impetigo. Cuts, scrapes, grazes, and insect bites should be washed immediately and kept clean. 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:
- Wash the affected areas with a neutral soap and running water
- Then cover the area lightly with gauze
- Do not touch the sores and encourage the patient not to touch the sores
- The patient's clothes, bedding, towels, and other toiletries should be washed daily
- The patient's clothes must not be shared or worn by other people
- When applying antibiotic ointment, gloves should be worn, washing hands thoroughly afterward
- Keep the patient's nails short to reduce scratching
- Wash hands and the patient's hands often
- Isolate the patient until they are not contagious
To prevent a recurrence of impetigo, make sure any skin condition, such as eczema, is treated properly.