One of the most important functions of the skin is to act as a barrier against infection in the outside world. This natural barrier is impaired in atopic eczema making people of all ages who have this skin complaint more vulnerable to certain bacterial and viral skin infections, particularly Staphylococcus aureus and Herpes simplex.
Staphylococcus aureus (Staph aureus) is a bacterium. There are about 30 different species of Staphylococcus, many of which live harmlessly on the skin's surface. However, Staph aureus is a potential pathogen or 'bad guy' which can cause several skin problems including folliculitis (a spotty rash due to infection of the hair follicles), boils and abscesses. Certain rarer strains of Staph aureus can cause a crusty yellow rash called 'impetigo', which is highly contagious.
People with atopic eczema are more vulnerable to skin infections with Staph aureus because it adheres to their skin more easily, and penetrates through the tiny cracks in the skin surface. This means that virtually all atopic eczema sufferers have Staph aureus on their skin. When low levels of bacteria are present and there are no obvious signs of infection, the skin is said to be 'colonized'. However, Staph aureus can thrive and multiply on eczema skin. When the bacterial load increases, signs of infection appear and the eczema flares. On infected eczema there may be over 10 million bacteria on a patch of skin the size of a fingernail. Staph aureus is rarely found on the skin of people who do not have atopic eczema, although they may carry it at certain body sites such as inside the nose without any ill effects.
Why Is Staphylococcus Aureus Bad For Eczema?
When Staph aureus proliferates (overgrows) on atopic eczema skin, it boosts the already over-active immune system and can trigger an itchy flare. Scratching causes more damage to the skin surface as well as bleeding and weeping, and this provides an ideal environment for more bacterial growth. This leads to higher levels of Staph aureus and a vicious circle of infection and worsening eczema. Certain strains of Staph aureus act as if 'turbo charged' and release toxins called 'superantigens', which trigger a very vigorous reaction.
The importance of Staph aureus in eczema has been shown in experiments where these bacteria were applied to the skin. In normal skin, this application triggered a small patch of eczema, but when Staph aureus was applied to the forearm of eczema sufferers, it caused a more widespread flare spreading to the elbow crease.
It is not possible to permanently eradicate Staph aureus from the skin of atopic eczema sufferers, but levels can be kept low by getting the eczema under good control, and using moisturizers to restore the skin's outer barrier.
Treatment Of Staph Aureus Infection
The choice of treatment for Staph aureus infection usually depends on how badly the skin is infected.
For milder infections with a minor eczema flare, it may be possible to reduce the level of bacteria simply by treating the eczema actively with moisturizers and topical steroids. Bath oils and soap substitutes with added antiseptics may help reduce infection, and some dermatologists recommend these on a long-term basis in children or adults who have repeated infective flares. Antiseptics that are widely used in eczema products include benzalkonium chloride, triclosan and chlorhexidine. Bathing in a dilute solution of potassium permangonate will dry up weeping infections.
Sometimes a topical antibiotic will be prescribed, usually as a combined formulation with a steroid. Several combination creams and ointments exist, but it is best to avoid using them as a long-term treatment because this can encourage resistant bacteria to develop.
If there are signs of heavy bacterial infection with a lot of redness, oozing, crusting and pustules (spots), a course of oral antibiotics is needed. The most commonly prescribed oral antibiotics for treating infected eczema are flucloxacillin and erythromycin. These usually work quickly and the eczema should improve in a few days. However, if other measures are not included to keep it under control and restore the skin barrier, the infection will usually relapse quickly after the antibiotic treatment is completed.
General hygiene measures for people with infected eczema at home include the following:
- Use antibiotic or antiseptic treatment as prescribed and for the full length of treatment
- Bath or shower every day
- Use separate hand and bath towels
- Avoid face cloths which may harbor bacteria
- Change bed linen regularly and wash in a hot wash
- Do not prepare food without wearing gloves if the hands are affected.