What Is Impetigo? What Causes Impetigo?

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Main Category: Dermatology
Also Included In: Pediatrics / Children's Health;  Infectious Diseases / Bacteria / Viruses
Article Date: 04 Sep 2009 - 0:00 PDT

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Impetigo is a highly contagious skin infection that is most common in children, it is caused by the staphylococcus aureus, or more rarely streptococcus pyogenes bacteria. Children account for about 70% of all cases. The first sign of impetigo is a patch of red, itchy skin. In colder countries most cases of impetigo are caused by staphylococcus aureus, while in warmer countries the infection can be caused by both types of bacteria.

In northern Europe, northern USA and Canada impetigo is the most common childhood skin infection.

According to Medilexicon's medical dictionary, impetigo is " A contagious superficial pyoderma, caused by Staphylococcus aureus and/or group A streptococci, which begins with a superficial flaccid vesicle that ruptures and forms a yellowish crust; most commonly occurs in children."

There are two types of impetigo: Children aged between two and four 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.

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.

What are the symptoms of impetigo?

Non-bullous impetigo (Impetigo contagiosa)

Red sores appear, generally around the mouth and nose. 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.

Bullous impetigo

This type mainly affects babies and children under the age of two.

Fluid-filled blisters appear, generally on the trunk, legs and arms. The skin around the blister is generally red and itchy, but not sore. They often spread rapidly and eventually burst, leaving a yellow crust. The crust eventually 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 more common in patients with bullous impetigo.

What causes impetigo?

Impetigo is caused by two types of bacteria: 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 spread rapidly.

There are two ways the infection can start: Symptoms do not appear until four to ten days after initial exposure to the bacteria. During those days people can pass the infection on to others, and tend to do so 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.

How is impetigo diagnosed?

Impetigo is fairly easy to diagnose and a GP (general practitioner, primary care physician) will do so after 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 come up on top of another skin condition, such as scabies.

Further tests may be ordered if: 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 help. A swab may also help determine whether another infection is present, such as ringworm or shingles.

If the patient is getting recurrent episodes of impetigo the doctor may take a swab from the nose to determine whether the infective bacteria is harboring there.

What are the treatment options 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 child can go back to school 48 hours after antibiotic treatment started, or when the sores have crusted and healed.

Complications of impetigo

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.

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: To prevent a recurrence of impetigo make sure any skin condition, such as eczema, is treated properly.

Written by Christian Nordqvist

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Christian Nordqvist. "What Is Impetigo? What Causes Impetigo?." Medical News Today. MediLexicon, Intl., 4 Sep. 2009. Web.
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