Controlling the skin microbiome in eczema
Atopic dermatitis (eczema) is a chronic inflammatory skin condition. Eczema mostly affects children but some adults suffer from the condition as well. People with eczema suffer from severely itchy skin that results in inflamed, red, and rough patches of skin mostly on the inner side of the elbows and behind the knees. Eczema is likely caused by a dysfunctional skin barrier combined with inflammation in the skin.
It has been known for a while now that the skin of people with eczema is more likely to develop an infection. Normally, our skin cells and immune system work together very well to prevent skin infections. However, in people with eczema, some of these defensive abilities of the body become dysfunctional. This immune dysfunction of the skin in people with eczema leads to higher levels of bacteria compared to normal adults.
Although we are all covered (colonized) with bacteria, these bacteria rarely lead to actual disease (i.e. infections). This is not the case in people with eczema who often develop skin infections with a particular bacteria called Staphylococcus aureus (S. aureus). When S. aureus leads to infected eczema, the typical result is red skin patches that have a yellowish-golden crust on top of them. Studies have demonstrated that when compared to normal skin, people with eczema are colonized with S. aureus to a much greater extent.[1,3] Combining the facts that skin afflicted with eczema has an impaired barrier function and dysfunctional immunity with the higher numbers of S. aureus on the skin, it is not surprising that there is a higher frequency of eczema S. aureus infections.
Additionally, recent research suggests that the high presence of S. aureus on the skin of people with eczema may “drive” the disease by inducing more inflammation. The incidence of the more dangerous methicillin-resistant S. aureus (known as MRSA) is on the rise and is a cause for alarm for people with eczema. MRSA can turn a standard skin infection into a serious and potentially life-threatening condition because MRSA is resistant to many antibiotic medications.
Considering all of the above it should be clear that doctors are very concerned about S. aureus infections in patients with eczema. When patients with eczema come to see their doctors and have S. aureus-infected skin, treatment with antibiotics is often initiated.
Over the years it has become clear that repeatedly using antibiotics to treat skin infections in people with eczema is not a viable long-term solution and can have dangerous consequences.
In order to overcome this issue doctors and scientists have developed other strategies to prevent S. aureus infection in people with eczema.
Prevention is usually the best approach, as it tends to be more effective and less expensive. To date, the best-studied approach to preventing skin infections in eczema is the use of dilute bleach bath combined with the application of mupirocin (topical antibiotic medication) to the insides of the nose. Interestingly this approach not only helps to reduce the numbers of bacteria on the skin, but it also helped to improve the eczema rash. Importantly, bleach baths do not lead to antibiotic resistance and, if used appropriately, do not lead to irritation or decreased skin barrier function.[5-7]
The use of silver impregnated underwear has been promoted recently but there is little evidence available to assess its utility in people with eczema.
The use of topical probiotics seems to make sense in eczema: adding more “good bacteria” is safe and will help to restore the bacterial balance in the body. However, there are few studies available and not enough evidence to say whether this is helpful or not at this time.
Looking to the future, newer approaches are being studied to fight S. aureus skin infections. These approaches use antibodies to selectively attack parts of S. aureus that help it infect the skin. This approach will avoid the development of antibacterial resistance but is predicted to be expensive. Other approaches that are currently under investigation include the use of cationic steroids and adenovirus to help the skin cells make more antimicrobial peptides. Antimicrobial peptides are protein molecules that can kill bacteria and are known to be decreased in the skin of people with eczema.