Impetigo

1 What is Impetigo?

Impetigo, one of the most common skin infections among kids, usually produces blisters or sores on the face, neck, hands, and diaper area.

This contagious superficial skin infection is generally caused by one of two bacteria: Staphylococcus aureus or Streptococcus pyogenes(also called group A streptococcus, which also causes strep throat). Methicillin-resistant Staphylococcus aureus (MRSA) is also becoming an important cause of impetigo.

Impetigo usually affects preschool and school-age children. A child may be more likely to develop impetigo if the skin has already been irritated by other skin problems, such as eczema, poison ivy, insect bites, and cuts or scrapes.

Routinely washing the face and hands can help prevent impetigo, which often develops when there is a sore or a rash that has been scratched repeatedly (for example, poison ivy can get infected and turn into impetigo).

Doctors can usually diagnose impetigo based on the appearance of the rash. Occasionally, they may need to take a sample of fluid from blisters. Impetigo is typically treated with either an antibiotic ointment or medication taken by mouth.

2 Symptoms

Symptoms of impetigo are:

  • One or many blisters those are filled with pus and easy to pop. In infants, the skin is reddish or raw-looking where a blister has broken.
  • Blisters that itch, are filled with yellow or honey-colored fluid, and ooze and crust over
  • Rash that may begin as a single spot, but spreads to other areas with scratching
  • Skin sores on the face, lips, arms, or legs that spread to other areas
  • Swollen lymph nodes near the infection

Impetigo may affect skin anywhere on the body but commonly occurs around the nose and mouth, hands, and forearms, and in young children, the diaper area.

The two types of impetigo are non-bullous (crusted) and bullous(large blisters):

  • Non-bullous or crusted impetigo is most common. It's usually caused by S. aureus but also can be due to infection with S.pyogenes. Non-bullous begins as tiny blisters that eventually burst and leave small wet patches of red skin that may weep fluid. Gradually, a yellowish-brown or tan crust covers the affected area, making it look like it has been coated with honey or brown sugar.
  • Bullous impetigo is nearly always caused by S. aureus, which releases toxins that trigger the formation of larger fluid-containing blisters that appear clear, then cloudy. These blisters are more likely to stay longer on the skin without bursting.

3 Causes

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 spread rapidly.

There are two ways the infection can start:

  • Primary impetigo - the bacteria invade the skin through a cut, insect bite, or other lesion
  • 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 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.

4 Making a Diagnosis

Impetigo is fairly easy to diagnose, and a 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.

Secondary impetigo can occur due when bacteria invade the skin because of another skin infection or condition has disrupted the skin barrier, such as eczema or 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 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.

5 Treatment

Treatment options for impetigo include topical antibiotics, systemic antibiotics, and topical disinfectants. Topical antibiotics are more effective than placebo and preferable to oral antibiotics for limited impetigo.

Systemic antibiotics are often reserved for more generalized or severe infections in which topical therapy is not practical. The ideal treatment should be effective, be inexpensive, have limited adverse effects, and should not promote bacterial resistance.

Topical antibiotocs

Topical antibiotics have the advantage of being applied only where needed, minimizing antibiotic resistance and avoiding gastrointestinal and other systemic adverse effects.

The length of time of topical treatment varies based on product, but in clinical trials, a seven-day course was more effective than placebo for resolution of impetigo.

Local allergic reactions, skin sensitization, and difficulty with application to areas such as eyelids, mouth, and back are potential disadvantages of topical treatments.

Three topical antibiotic preparations recommended for impetigo are mupirocin 2% cream or ointment (Bactroban), retapamulin 1% ointment (Altabax), and fusidic acid (not available in United States).

Empiric treatment considerations have changed with the increasing prevalence of antibiotic-resistant bacteria. Methicillin-resistant S. aureus (MRSA), macrolide-resistant streptococcus, and mupirocin-resistant streptococcus are now documented.

Retapamulin is a novel pleuromutilin antibacterial and the first new topical antibacterial in nearly 20 years. Pleuromutilins, derived from the fungus Clitopilus passeckerianus, have antibacterial activity against gram-positive bacterial organisms.

Retapamulin acts on three key aspects of bacterial protein synthesis, making it far less likely to induce resistant strains. In 2007, the U.S. Food and Drug Administration approved retapamulin 1% ointment for the treatment of impetigo due to S. aureus (methicillin-susceptible isolates only) or S. pyogenes in adults and children at least nine months of age.

Retapamulin is not approved for intranasal staphylococcal carrier treatment or treatment of MRSA-related skin infections.

Oral antibiotics

Oral antibiotic therapy can be used for impetigo with large bulla or when topical therapy is impractical. Treatment for seven days is usually sufficient, but this can be extended if the clinical response is inadequate and antibacterial susceptibility has been confirmed.

One study that lacked statistical power showed oral penicillin V potassium was no more effective than placebo. In other studies, penicillin V potassium was inferior to erythromycin and cloxacillin (no longer available in the United States), whereas topical mupirocin was slightly superior to oral erythromycin.

No macrolide was found to be better than another, but all were found superior to penicillin V potassium; however, because of increasing macrolide resistance, they are no longer a preferred option. Amoxicillin/clavulanate (Augmentin) was superior to amoxicillin alone because of its coverage of β-lactamase–producing organisms.

Although cephalosporins may be used, there is no evidence that one generation is better than another.

If MRSA infection is suspected, initial treatment with trimethoprim/sulfamethoxazole, clindamycin, or a tetracycline (doxycycline or minocycline [Minocin]) is recommended pending culture results. Although trimethoprim/sulfamethoxazole is effective for S. aureus infection, including most MRSA infections, its use for impetigo is limited by inadequate coverage of streptococcal bacteria.

Oral clindamycin penetrates skin and skin structures and should be considered if MRSA infection is suspected. Because of an increasing risk of pseudomembranous colitis, clindamycin should be reserved for patients allergic to penicillin, or for infections that fail to respond to other treatments.

Tetracyclines can be used for susceptible MRSA infections, but should be avoided in children younger than eight years. Oral fluoroquinolones are not preferred because of low staphylococcal activity and their potential association with tendinopathy and arthropathies.

Topical disinfectants

There are some studies on the benefits of nonantibiotic treatments, such as disinfectant soaps, but they lack statistical power.

Disinfectants appear to be less effective than topical antibiotics and are not recommended. Studies comparing hexachlorophene (not available in the United States) with bacitracin and hydrogen peroxide with topical fusidic acid found the topical antibiotic to be more effective.

Natural therapies

The evidence is insufficient to recommend or dismiss popular herbal treatments for impetigo. Natural remedies such as tea tree oil; tea effusions; olive, garlic, and coconut oils; and Manuka honey have been anecdotally successful.

The fact that impetigo is self-limited means that many “cures” could appear to be helpful without being superior to placebo.

6 Prevention

As impetigo is a highly contagious condition, it is very important to take hygiene precautions to prevent the spreading of infection to other people.

The advice below will help to prevent the spread of infection:

  • Keep children off nursery, playgroup or school until their sores have dried up, blistered, or crusted over, or until 48 hours after starting treatment.
  • Do not share flannels, sheets or towels with infected people, and wash them at a high temperature after use.
  • Wash the sores with soap and water, and cover them loosely with a gauze bandage or clothing.
  • Do not touch the sores.
  • Wash your hands frequently, particularly after touching infected skin.
  • Avoid contact with newborn babies until the risk of contagion has passed (when the rash has crusted over, or after at least 48 hours of treatment with antibiotics).
  • Washable toys should also be washed. Wipe non-washable soft toys thoroughly with a cloth that has been wrung out in detergent and warm water and allowed to dry completely.
  • Treat suspected or confirmed cases quickly.
  • Cover cuts and grazes with a plaster or dressing.

To prevent the impetigo returning, keep cuts and scratches clean, and ensure that any condition that causes broken skin, such as eczema, is treated promptly.

7 Alternative and Homeopathic Remedies

A few alternative remedies exist for impetigo.

Although antibiotics normally provide an effective way of clearing up impetigo, they can weaken your immune system in the process. For this reason, it makes sense to take steps to bolster your body’s defences.

There are numerous natural remedies that can help do this and, better still, many help fight the infection in the process.

You may find that you need to use a combination of the following for best results:

  • Goldenseal (Hydrastis canadensis): Researchers have discovered that Goldenseal contains anti-infective chemicals such as berberine, beta-hydrastine, canadine and canadaline. They have been found to be particularly effective against infections caused by staphylococcus and streptococcus which, are the two main culprits that cause impetigo. The recommended dosage amount for Goldenseal is one 250 mg tablet taken three times a day. Goldenseal is also available in cream or liquid forms for external use apply directly to the infected area of skin three times a day.
  • Olive oil: The use of olive oil as a mild antiseptic for the skin has been known since biblical times. Apply a few drops of olive oil over and around the infected area, four times a day. Olive oil is best used as a preventative. For example, you should apply olive oil if you are in contact with someone who already has impetigo; especially if you have any type of skin injury as this dramatically increases your risk of catching it.
  • Tea Tree oil (Melaleuca alternifolia): Scientists found that ordinary tea appears to offer protection against the infection too. Positive results were reported for an ointment containing tea leaf extract in impetigo contagiosa infections. Apply two to three drops of tea tree oil to the affected area three times a day.
  • Zinc: Several studies have shown that this mineral plays a key role in improving immunity. In addition, a study has revealed that zinc can reduce the risk of impetigo developing in premature babies. This is an important finding, as these babies have immature immune systems which make them vulnerable to developing infections like impetigo. The recommended dosage of zinc (as zinc citrate) for adults is 15 mg daily.
  • Myrrh (Commiphora mol-mol): Myrrh oil is able to reduce levels of inflammatory chemicals, such as interleukin and tumour necrosis factor, in the blood. This is important, as keeping concentrations of these chemicals to a minimum means that your body stands a far better chance of successfully fighting off infections. Manuka honey in particular is extremely effective for treating serious infections, including MRSA. To benefit from manuka honey, take two to three teaspoonfuls (10-15g) before meals. A few drops of myrrh can be added to water, for external use, to wash the infected area.

8 Risks and Complications

Complications of impetigo are rare but they can occasionally be serious. So you should stay alert for any changes or worsening in symptoms and report them to your GP.

Complications include:

  • Cellulitis: Cellulitis occurs when the infection spreads to a deeper layer of skin. Cellulitis can cause symptoms of red inflamed skin, fever and pain. The condition can be treated with antibiotics, and paracetamol can be used to relieve symptoms of pain.
  • Guttate psoriasis: Guttate psoriasis is a non-infectious skin condition that can develop in children and teenagers after a bacterial infection. It is normally more common after a throat infection, but some cases have been linked to impetigo. It causes small (less than 1 cm/one third of an inch) droplet-shaped sores on the chest, arms, legs and scalp. Creams can be used to help control the symptoms of guttate psoriasis.
  • Scarlet fever: Scarlet fever is a rare bacterial infection that causes a fine pink rash across the body. Associated symptoms of infection such as nausea, pain, and vomiting are common. The condition is usually treated using antibiotics. Scarlet fever is not normally serious, but it is contagious, so it is important to isolate an infected child and avoid close physical contact. You should keep your child away from school and other people until they have had at least five days treatment with antibiotics.
  • Septicaemia: Septicaemia is a bacterial infection of the blood. It can cause symptoms of fever, rapid breathing and vomiting. Also the person may feel confused, faint and dizzy. Septicaemia is potentially life-threatening and requires immediate admission to hospital for treatment with antibiotics.
  • Post-streptococcal glomerulonephritis: Post-streptococcal glomerulonephritis is a very rare complication of impetigo. It is an infection of small blood vessels in the kidneys. Symptoms of the condition include a change in the colour of urine to a reddish-brown, or cola, colour. Post-streptococcal glomerulonephritis also causes a rise in blood pressure. Post-streptococcal glomerulonephritis can be fatal in adults, but deaths in children are very rare. In fact, less than 1% of children who develop post-streptococcal glomerulonephritis die as a result of the condition. People with post-streptococcal glomerulonephritis will normally require hospital treatment so that their blood pressure can be monitored and controlled.
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