What Is Impetigo?


A Look Into Impetigo

Impetigo (pronounced im-puh-ty-go) is a common, highly contagious bacterial skin infection. It mostly affects young children and infants, however, people of any age can get it from contact with someone who is infected. Most impetigo is caused by Staphylococcus Aureus or “Staph” infection bacteria for short. The infection isn’t usually serious, but sometimes complications may develop. Impetigo affects the outer layers of skin. The face, arms, and legs are the areas most often affected. Topical antibiotics usually clear up impetigo in 7 to 10 days. It can also clear up on its own in 2 to 4 weeks, but antibiotics are recommended to reduce complications.

Skin Conditions: Impetigo


Anyone can get impetigo, but the infection is most common among children, but it seems to affect children ages 2 to 6 the most. In fact, the condition accounts for about 10 percent of skin problems seen in pediatric clinics. The impetigo infection most often begins in minor cuts, insect bites, a rash like dermatitis or eczema, or any place there is broken skin.  It can also occur on healthy skin, referred to as “Primary” Impetigo.  “Secondary” Impetigo occurs when the skin is broken.

A Very Old Disease

Impetigo is an old disease that has been traced back to approximately 14th-century England. It comes from the Latin word “impetere,” which means “to attack.” The open sores are highly contagious, itchy, and sometimes painful. Scratching the sores can spread the infection from one place on your skin to another, or to another person. The infection can also spread from anything an infected person touches.

Because it spreads so easily, impetigo is known as the “school disease.” It can spread like wildfire from child to child, in a classroom, in a day-care center, or anywhere children are in close contact. For this same reason, it also spreads among families quite easily.

Hygiene Is Key

Hygiene is essential to control impetigo’s spread. If you or your child has impetigo, you need to wash and disinfect everything the infection might come in contact with. That means clothes, bedding, towels, toys, sports equipment or anything else you can think of. Topical antibiotics can usually clear up impetigo in days, and shorten the length of time that the disease is contagious.

Impetigo Is a Global Problem

Impetigo is a global disease that has remained at the same incidence levels for nearly 50 years. An estimated 162 million children worldwide have impetigo at any one time. Impetigo is more prevalent in developing countries, and in the poor areas of industrial countries. The bacteria thrives in hot, moist conditions. So impetigo tends to be seasonal, peaking in the summer and fall in northern climates. But in warm and humid climates, it can occur year-round.


Common symptoms of impetigo include reddish spots on the skin, often clustered around the nose and lips, are the first sign of the most common type of impetigo. The sores quickly grow into blisters, ooze and burst, and then form a yellowish crust. The crust is often described as honey-colored. The clusters of blisters may expand to cover more of the skin. The sores are unsightly, itchy, and occasionally painful. After the crust phase, they leave red marks, but fortunately they fade without leaving scars.

Infants often have a less common form of impetigo, with larger blisters around the diaper area or in skin folds. These fluid-filled blisters soon burst, leaving a scaly rim called a “Collarette.” Impetigo can be very uncomfortable. Occasionally, it may involve fever, and possibly even swollen glands in the area of the outbreak, in more severe cases of the condition.

Types of impetigo

There are three types of impetigo:

Nonbullous: Also called “Impetigo Contagiosa,” It’s the most common form of impetigo, an estimated 70 percent of cases. It’s usually caused by Staph or Strep, or by a combination of both. It usually starts with reddish spots that develop into small red blisters around the mouth and nose. The blisters range in size from 1 to 2 centimeters in diameter. The clusters of blisters may spread to other skin areas.

After a few days, the blisters burst and develop a brownish-yellow crust. The surrounding skin can look red and raw. Nonbullous impetigo is itchy, but not painful. When the crusts heal, there are reddish spots that fade and don’t leave scars. Nonbullous impetigo rarely occurs in children under age 2.

Bullous: It usually forms larger blisters or bullae filled with a clear fluid that becomes darker and cloudy. The blisters can be up to 2 centimeters in diameter. Typically, the blisters begin on unbroken skin and aren’t surrounded by reddish areas. The blisters become limp and then burst open. Then a yellowish crust forms over the sore. Bullous impetigo is most common in newborns, especially in the diaper area or neck folds. For other ages, the blisters appear most often on the trunk and arms and legs. Fortunately, the blisters rarely leave scars once they have healed.

Ecthyma: This infection can be more severe. It forms small, pus-filled sores with a thicker crust. But ecthyma goes deeper into the skin than the other forms of impetigo. Ecthyma sometimes may be accompanied by swollen glands. Ecthyma blisters can be painful and can develop into larger, deeper sores. These sores progress to have a thick crust surrounded by reddish-purple skin.

Most often ecthyma appears on the buttocks, thighs, legs, ankles, and feet. Sometimes, untreated nonbullous or bullous impetigo can develop into ecthyma. The ecthyma lesions heal slowly and may leave scars after they heal. That is why it’s imperative to seek out your doctor or health care professional immediately for assistance.

Causes of Impetigo

It’s important to remember impetigo is a bacterial infection. Your skin surface and the inside of your nose are normally home to large numbers of friendly or “Commensal” bacteria that help protect you from disease-causing bacteria such as Staph and Strep. Your commensal bacteria work to keep down the population of pathogenic bacteria by producing substances that are toxic to the pathogens. However, strains of these Staph or Strep bacteria are very strong and can take advantage of a break in the skin from a cut, scratch, insect bite, or rash to invade and colonize, causing impetigo. The bacteria can also colonize and cause an infection on normal skin. It’s not known exactly why this happens.

How It Works

Within about 10 days of bacteria colonization, impetigo blisters appear. The way it works is that the Staphylococcus Aureus and Streptococcus Pyogenes bacteria produce toxins that break apart your top skin layers, causing blisters to form. In many cases, the bacteria are already on site, waiting for an opportunity to colonize.  These bacteria are normally carried in the nose by between 20 and 50 percent of the general population. An even larger percentage of people are intermittent carriers. Further, about 10 to 20 percent of healthy people have Staphylococcus aureus bacteria in their Perineum (the area between the genitals and the anus).

For people who are Staph “carriers,” infection is thought to be spread by the person from their nose or other area to the skin. In contrast, strep-caused impetigo usually begins with the strep bacteria spreading to the skin from a person with impetigo. Normally strep doesn’t survive on skin for more than a few hours. It’s not known why the strep bacteria are able to stay on the skin of people who develop impetigo for 10 days, before the blisters appear.

Strains of strep bacteria behave differently. Research has shown that some strains of strep bacteria cause throat infections, while others cause skin infections. So why do some people carry staph and strep bacteria without developing impetigo?  It’s thought that some individuals are more able to resist infection because of the chemical makeup of their skin and their general good health.

Other factors can make a difference in the growth of Staph and Strep bacteria that cause impetigo:

  • Poor hygiene is the biggest culprit. It aids the spread of bacteria. A good education in proper hygiene can reduce the chance of outbreaks by over 50%.
  • Disease-causing bacteria thrive in hot humid weather, so keeping cool and reducing temperatures when possible is helpful.
  • Working or living in close crowded conditions can rapidly promote impetigo spread. This includes schools or military environments, especially in tropical areas.
  • Sports that involve skin-to-skin contact, such as football, wrestling, or jiu-jitsu dramatically increase risk of infection and/or outbreak.

To Summarize:

  • Staph and Strep bacteria invade the skin to cause impetigo, by releasing toxins that break down the skin layer, forming blisters.
  • Hot and humid weather, crowded conditions, and poor hygiene aid the spread of bacteria.
  • Impetigo is highly contagious. It spreads on direct contact with a skin sore or with anything that may have touched an open sore.
  • Though uncommon, impetigo can also spread by contact with bedding, underwear and clothes, towels and washcloths, toys, sports equipment, and anything else that came in contact with an open sore.

At-risk populations are at greatest risk. Children 2 to 6 years old, especially those in a day care center or play group, are the most vulnerable

Adults and children are more at risk if they:

  • Live in a warm, humid climate
  • Have diabetes
  • Are undergoing dialysis
  • Have a compromised immune system, such as from HIV
  • Have skin ailments such as eczema, dermatitis, or psoriasis
  • Have sunburn or other burns
  • Have itchy infections such as lice, scabies, herpes simplex, or chickenpox
  • Have insect bites or poison ivy
  • Participate in contact sports

Treating Impetigo

  • If you’re using a topical antibiotic, the sores are contagious until they stop oozing and dry up.
  • If you’re taking an oral antibiotic, the infection usually won’t be contagious after 24 to 48 hours.

Antibiotics for Treatment

Recommended treatment with topical antibiotics should run for approximately 5 to 7 days, but be sure to consult with your doctor or health care professional for assistance.  Specific topical antibiotics recommended are Mupirocin and Fusidic acid. If the impetigo is severe or widespread, oral antibiotics are recommended. These might work more quickly than topical antibiotics, but a doctor will help make that assessment for you.

Recommended oral antibiotics include anti-staphylococcal penicillins, amoxicillin/clavulanate (Augmentin), cephalosporins, and macrolides. Erythromycin was found to be less effective.

NOTE:  Oral antibiotics can have more side-effects than topical antibiotics, such as nausea. Also, there is some evidence of antibiotic resistant staph in impetigo treatment.

Home Treatments

You can aid the healing and the appearance of impetigo with home treatments, cleaning and soaking and bleach baths. Cleaning and soaking the sores is recommended 3 to 4 times a day. Make sure to wash your hands thoroughly after treating the impetigo sores:

  • Gently clean the sores with warm water and soap and then remove the crusts from nonbullous impetigo. Removing the crusts exposes the bacteria underneath. You can also soak the affected area in warm soapy water before removing the crusts.
  • Cleaning or soaking and crust removal should be done regularly until the sores heal. Dry the area and apply antibiotic ointment. Then cover the sores lightly with gauze.
  • For a minor outbreak, you can use an over-the-counter antibiotic ointment.
  • Apply it three times a day, after cleaning the area. Then cover the sore with a bandage or gauze.

Another home treatment is a 15-minute bleach bath with a very diluted solution of household bleach (2.2 percent). This reduces the bacterial level on the skin, but needs to be done regularly.  For a full-size bath, use one-half cup of bleach. A full bath usually has 80 liters (21 gallons) of water. Rinse off with warm water and pat dry. Note that some people may have an allergic reaction to bleach.

Other, more serious complications of impetigo include:

  • Cellulitis, a serious infection – Staphlococcus aureus of the tissues under your skin, which can spread to the bloodstream.
  • Lymphangitis, an inflammation of the lymphatic channels.
  • Sepsis, a bacterial infection of the blood.
  • Scarlet fever, a rare bacterial infection caused by Streptococcus pyogenes.
  • Guttate psoriasis, a non-infectious skin condition that can infect children and young adults after a skin infection
  • Staphyloccus scalded skin syndrome (SSSS), another serious skin condition

Good hygiene is number one for prevention:

  • Regular bathing and frequent hand washing can cut down on skin bacteria.
  • Cover any skin wounds or insect bites to protect the area.
  • Keep nails clipped and clean.
  • Don’t touch or scratch open sores. This will spread the infection.
  • Wash everything that comes in contact with the impetigo sores in hot water and some laundry bleach (7).
  • Change bed linens, towels, and clothing every day, until the sores are no longer contagious (7).
  • Clean and disinfect surfaces, equipment, and toys that may have come in contact with impetigo.
  • Don’t share any personal items with someone who has impetigo.

Impetigo can be very serious, so please contact your doctor or health care professional for assistance.

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