Skin Microbiome Diversity and Eczema: What the Research Shows
Eczema, often called atopic dermatitis, is a common skin condition that causes dryness, itching, and inflammation. For many years, it was mainly understood as a problem of the skin barrier or immune system. More recent research has added another important piece to the picture: the skin microbiome. The skin microbiome refers to the collection of bacteria, fungi, and viruses that live on the surface of the skin. These organisms are not just passive residents. They interact with the immune system, help protect against harmful microbes, and play a role in maintaining healthy skin. When this system becomes unbalanced, it can contribute to conditions like eczema. What Is the Skin Microbiome and
Why Diversity Matters
Healthy skin is home to a wide range of microorganisms. This diversity is important. Different species perform different roles, such as preventing harmful bacteria from taking over, supporting the skin barrier, and helping regulate inflammation. Research shows that the skin microbiome is established early in life and contributes to immune system development and stability over time. When the microbiome is balanced and diverse, it acts like a protective ecosystem. When diversity is reduced, this balance breaks down. This state is often referred to as dysbiosis. In eczema, dysbiosis is a consistent finding. Studies show that people with eczema tend to have fewer types of bacteria on their skin compared to people without the condition. This loss of diversity is not just a background detail. It is closely linked to how severe symptoms become.
What Happens to the Microbiome in Eczema
One of the most consistent findings in eczema research is the dominance of a single type of bacteria: Staphylococcus aureus.In healthy skin, many different microbes coexist. In eczema, this balance shifts. During flare-ups, bacterial diversity drops and Staphylococcus aureus becomes much more abundant. This matters because this bacterium is not neutral. Research shows it can:
Produce toxins that irritate the skin
Trigger immune responses that increase inflammation
Damage the already weakened skin barrier
This creates a feedback loop. A weakened skin barrier allows harmful bacteria to grow more easily. Those bacteria then worsen inflammation and further damage the barrier.In addition, studies suggest that not all strains of bacteria are the same. Certain strains of Staphylococcus are more strongly associated with eczema severity, meaning the specific makeup of the microbiome also matters, not just the presence of bacteria.
How Microbiome Changes Affect Symptoms
Understanding microbiome changes helps explain common eczema symptoms in a more concrete way.
Increased inflammation
When harmful bacteria dominate, they stimulate the immune system. This leads to redness, swelling, and irritation. Research shows that microbiome imbalance is directly tied to inflammatory processes in eczema.
Itching and flare cycles
The toxins and enzymes produced by certain bacteria can irritate nerve endings in the skin. This contributes to itching, which leads to scratching, further damaging the skin and worsening the condition.
Dryness and barrier breakdown
The skin barrier relies on both physical structure and microbial support. When beneficial microbes are reduced, the barrier becomes less effective at retaining moisture and keeping irritants out.
Flare variability
Studies show that microbiome composition can change depending on the body site and over time. This helps explain why eczema may appear in certain areas, improve, then flare again unpredictably.
Why Microbiome Diversity Is Reduced in Eczema
Research points to several overlapping causes for reduced microbial diversity.
Many people with eczema have a weakened skin barrier. This can be influenced by genetics, such as changes in proteins that help maintain the outer skin layer. A compromised barrier makes it easier for certain bacteria to dominate. The gut-skin axis is a crucial modulator of overall skin health.
The immune system in eczema reacts differently to microbes. Instead of maintaining balance, it may overreact to some organisms while failing to control others.
Factors such as antibiotic use, hygiene practices, and even close contact with others can influence which microbes are present on the skin.
In healthy skin, some bacteria actively suppress harmful ones. When these beneficial microbes are reduced, harmful species have more opportunity to grow.
What This Means for Treatment and Skin Care
Research on the microbiome is changing how eczema is approached. Instead of focusing only on reducing inflammation, there is growing interest in restoring microbial balance.
Moving beyond “killing bacteria”
Traditional approaches often involve antimicrobial treatments. While these can reduce harmful bacteria, they may also reduce beneficial microbes, which can limit long term effectiveness. Research suggests that simply eliminating bacteria does not reliably restore a healthy microbiome.
Supporting microbial balance
Newer approaches aim to support or reintroduce beneficial bacteria rather than remove all microbes. This includes research into topical probiotics and microbiome-based therapies.
Strengthening the skin barrier
Because the microbiome and skin barrier are closely linked, improving barrier function helps support a healthier microbial environment. This can reduce the likelihood of harmful bacteria taking over.
Personalized variation
Microbiome composition varies between individuals. Research suggests that eczema may not be identical from person to person at the microbial level, which may explain why treatments work differently for different people.
Key Takeaways
Healthy skin contains a diverse mix of microorganisms that help protect and regulate the skin. Eczema is associated with reduced microbiome diversity and dominance of certain harmful bacteria. Lower diversity is linked to more severe symptoms and flare-ups. Harmful bacteria can worsen inflammation, itching, and barrier damage. The microbiome interacts closely with both the immune system and the skin barrier. Restoring balance, rather than eliminating all bacteria, is an emerging focus in treatment. Individual differences in microbiome composition may influence how eczema develops and responds to care
PubMed Article Links
https://pubmed.ncbi.nlm.nih.gov/36924444/ https://pubmed.ncbi.nlm.nih.gov/37232427/ https://pubmed.ncbi.nlm.nih.gov/35384293/ https://pubmed.ncbi.nlm.nih.gov/34551705/ https://pubmed.ncbi.nlm.nih.gov/38024036/ https://pmc.ncbi.nlm.nih.gov/articles/PMC9189751/ https://pmc.ncbi.nlm.nih.gov/articles/PMC7147826/ https://pmc.ncbi.nlm.nih.gov/articles/PMC4122000/
