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Impetigo

Definition

Impetigo is a skin infection. It often appears as blisters around the mouth and nose but it can infect skin anywhere on the body. Impetigo can easily spread from one person to another. This infection occurs most often in children.

Impetigo: Sores on the Upper Lip
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Causes

Impetigo is caused by bacteria. The most common type of bacteria associated with this infection includes:

  • Group A Streptococcus
  • Staphylococcus

These types of bacteria are normally found on the skin and in the nose. The bacteria do not cause trouble until it gets under the skin. Bacteria get in under the skin through small cuts, scratches, or insect bites.

Risk Factors

Factors that increase your chance for impetigo include:

  • Age: most impetigo occurs in preschool and school-aged children
  • Touching a person with impetigo
  • Touching the clothing, towels, sheets, or other personal items that belong to a person with impetigo
  • Poor hygiene, particularly unwashed hands and dirty fingernails
  • Crowded settings where there is direct person-to-person contact, such as schools and the military
  • Contact sports such as football and wrestling
  • Warm, humid environment
  • Summer season
  • Poor health or weakened immune system
  • Tendency to have skin problems such as eczema, poison ivy, or skin allergy
  • Cuts, scratches, insect bites, or other injury to the skin
  • Chickenpox
  • Lice infections which cause scratching (like scabies, head lice, or pubic lice)

Symptoms

Symptoms of impetigo appear 4-10 days after contact with the bacteria.

The main signs of impetigo are skin lesions. They occur most often on the face, arms, or legs but can appear anywhere on the body. The lesions may be red spots, sores, or blisters. The lesion may:

  • Ooze and become covered with a flat, dry, honey-colored crust
  • Itch
  • Increase in size
  • Spread, especially if scratched

There may also be swollen lymph nodes in the area with more serious infections.

Impetigo is normally a fairly mild condition. However, further problems could develop if it is not treated. The infection could spread. This can lead to pain, swelling, pus, or fever. Rarely, impetigo that is caused by Group A Streptococcus may develop into:

  • Glomerulonephritis—damage to part of the kidney
  • Scarlet fever—illness that may include a fever, sore throat, and widespread rash
  • Life-threatening invasive streptococcal disease

Diagnosis

Your doctor will ask about your symptoms and medical history. The skin lesions will be examined. Your doctor will be able to diagnose impetigo by the look of your skin lesions.

Your doctor may test a sample of the infected skin. This will show what specific bacteria are causing the infection. It may help to guide treatment choices.

Treatment

The goals of treatment are to relieve the symptoms and cure the infection.

Treatment may include:

Antibiotics

Antibiotics are a type of medicine that can fight bacteria. For a mild infection, your doctor may recommend:

  • Prescription topical antibiotic (such as mupirocin, retapamulin)
  • Over-the-counter topical antibiotic such as neomycin, bacitracin, or polymyxin—may be significantly less effective
  • Topical antibiotics for the inside of the nose—bacteria can hide in the nose and make it easy for the infection to return

Your doctor may prescribe oral antibiotics, such as:

  • Cephalosporin
  • A penicillin

In some cases, staphylococcal infections (such as MRSA) may be resistant to these antibiotics. Others options may be needed.

Skin Care

Good skin care is important with this type of infection. It can help prevent the spread of the infection to other areas of your skin or to others. In general:

  • Do not touch or scratch the lesions.
  • Wash the skin several times a day. Use soap and water or an antibiotic soap.
  • The crusts may be removed by soaking the infected area. Place warm water on the area for about 15 minutes.
  • Lesions should be covered loosely with gauze, a bandage, or clothing.

Avoiding Spread of the Infection

To help avoid spreading the infection:

  • Wash your hands often and thoroughly. Make sure you wash under your fingernails where bacteria can hide. It is important to wash your hands after touching an infected area of your body.
  • Avoid contact with newborn babies.
  • Stay home until you have had treatment for 24 hours.
  • Do not handle food at home until you have had treatment for at least 24 hours.
  • If you work in the food service industry, ask your doctor when it is safe for you to return to work.

Prevention

Prevention of impetigo involves good personal hygiene. The following tips can help:

  • Bathe daily with soap and water.
  • Wash your face, hands, and hair regularly.
  • If caring for someone with impetigo, be sure to wash your hands after each time you touch the person.
  • Do not share towels, clothes, or sheets. This is more important with a person who has impetigo.
  • Keep fingernails short and clean.
  • Change and wash clothing often.
  • Do not let your children play or have close contact with someone who may have impetigo.
  • Wash wounds, such as cuts, scratches, or insect bites, with soap and water. Consider applying a small amount of antibiotic ointment. Cover the wound with a bandage.

Revision Information

  • American Academy of Dermatology

    http://www.aad.org

  • Kid's Health for Parents

    http://www.kidshealth.org

  • Canadian Dermatology Association

    http://www.dermatology.ca

  • Dermatologists.ca

    http://www.dermatologists.ca

  • American Osteopathic Association website. Available at: http://www.osteopathic.org/osteopathic-health/about-your-health/health-conditions-library/general-health/Pages/impetigo.aspx. Accessed July 27, 2012

  • Impetigo. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated March 15, 2012. Accessed July 27, 2012.

  • Koning S, van der Wouden JC, et al. Efficacy and safety of retapamulin ointment as treatment of impetigo: randomized double-blind multicentre placebo-controlled trial. Br J Dermatol. 2008;158(5):1077-1082.

  • Maryland Department of Health and Mental Hygiene website. Available at: http://ideha.dhmh.md.gov/IDEHASharedDocuments/impetigo.pdf. Updated April 2008. Accessed July 27, 2012.