Impetigo

Impetigo is a fairly common and highly contagious superficial bacterial skin infection that affects children more than adults.

Summary

• Impetigo is a skin condition caused by bacteria.
• Impetigo needs prompt attention because it is highly contagious.
• Impetigo mainly affects children.
• Correctly treated impetigo leaves no ill effects.

Definition

Impetigo is a fairly common and highly contagious superficial bacterial skin infection that affects children more than adults.

It usually affects exposed areas of the arms and legs and the face, especially around the nose and mouth. Infected areas may range from the size of a 10c to a R5 coin.

Causes

Impetigo is caused by either staphylococci (staph) or streptococci (strep) type of bacteria. These bacteria are everywhere: in grimy bathrooms, in spoiled food and as part of the normal bacterial flora in our own bodies.

They gain entry into the skin when a cut, crack, scratch, abrasion, insect bite or an area of eczema comes into contact with these bacteria, for example by bathing in a dirty bathtub or by using a towel or soap previously used by an infected person. People who also have other skin problems are more susceptible to impetigo.

Physical contact, such as scratching an infected area, can spread the bacteria to other parts of the body and even to other people. Sharing clothing, bedding and other objects also spread the infection. Excessive sweating, malnutrition and poor hygiene can exacerbate the condition.

Who gets it and who is at risk?

Children are the primary victims and carriers of impetigo because their activities involve large groups and close contact, especially at school.

Although impetigo is most common in children, almost anyone can get it. Those who live in poor hygienic conditions are more susceptible to impetigo, especially if they also have other skin problems.

Symptoms and signs

The infection starts with a patch of swollen red skin that may develop into blisters. After a few hours the blisters break open into a red, moist area that oozes or weeps fluid. In a few days, a golden or honey-coloured crust is formed, resembling grains of brown sugar. The crust may continue to spread at the edges of the affected area.

In severe cases, the infection invades deeper skin layers and develops into ecthyma, an ulcerated form of the disease. The ulcers of ecthyma are filled with pus and may be itchy. The crusts are darker and thicker than those of impetigo. If left untreated, permanent scars and changes of the colour of the skin may result.

Glomerulonephritis is a potentially serious complication of impetigo, caused by some strains of streptococci. It is a kidney disease that appears in 1% of cases, mainly in children, but with the correct treatment most patients recover from the disease without lasting effect.

Diagnosis

The diagnosis of impetigo is clinical – that is, the characteristic changes in the skin are obvious and no investigations are usually needed.

Prevention

• Once an infection has occurred, special care of the infected person and prompt treatment will prevent the disease from spreading.
• Avoid direct contact with an infected area.
• Good personal hygiene and a clean environment will prevent impetigo.
• Wash all sores and scratches with soap and water.
• Keep the area between a child’s upper lip and nose clean to prevent infection, especially while the child has a cold.
• Keep fingernails short and clean.

 Treatment

Home

Regular washing with soap and water can clear up mild forms of impetigo.

For more serious cases, the following should supplement the doctor’s treatment:

• Remove the crusts by soaking the area in warm water for 15 or 20 minutes. Use a warm face-cloth for the face. Rub the area gently with the face-cloth and antibacterial soap. Gently pat the area dry. Repeat this treatment several times a day.
• Apply an antibiotic ointment (such as Bactroban or Fucidin ointment) to the infected areas. Cover them with gauze taped well away from the sores. This will prevent the spread of the infection through touching and scratching.
• Apply antibiotic ointment three to four times a day.
• Do not share towels, face-cloths, or bath water. Men should not shave over the sores. Use a clean razor every day.
• Wash the towels and face-cloths that an infected person has used separately. To prevent household members from infecting one another, the doctor may prescribe antibacterial baths for the whole family.

Medication

A topical antibiotic ointment and/or an oral antibiotic such as penicillin or erythromycin is usually very effective in clearing the infection within a few days. Antibacterial ointments (Bactroban or Fucidin) are also very effective

If a streptococcal infection is suspected, children should always be treated with an oral antibiotic.

Penicillin injections can be administered to protect patients against the complications of severe infections, shorten the healing time and reduce the chance of recurrence.

Outcome

Correctly treated and managed, impetigo clears up within a week or two without any complications.

In severe cases, ecthyma (an ulcerated form) may develop. If left untreated, this condition may cause permanent scars and pigment changes.

However, glomerulonephritis (a kidney disease) is a potentially serious complication of impetigo. It appears in 1% of cases, mainly in children, but with the correct treatment most patients recover from the disease without lasting effect.

When to see your doctor

• If the impetigo covers an area larger than 5cm in diameter.
• If there is no improvement after three to four days of home treatment, or if new areas of infection appear.
• If there is increased pain, swelling, heat, redness or tenderness.
• If red streaks extend from the areas.
• If there is continued discharge of pus.
• If there is a fever of 37.7 º C or higher with no other cause.
• If impetigo symptoms appear on a baby.
• If small, very itchy, pus-filled ulcers form, with a dark brown crust (symptoms of ecthyma).
• If a child suffering from impetigo develops nausea, headaches, low urine output, or puffiness around the face and on the limbs (symptoms of glomerulonephritis).

Previously reviewed by Prof H.F. Jordaan, MBChB, MMed (Derm)

Reviewed by Prof  Eugene Weinberg, FCPaeds [SA}, FAAAAI, Paediatrics and Paediatric Allergology, Allergy Diagnostic Unit,UCT Lung Institute, October 2011