Neurodermatitis, also known as atopic dermatitis, is a chronic inflammatory skin disease that affects millions of people worldwide. Typical symptoms such as itching, redness, scaly skin, and recurring bouts of inflammation place both a physical and psychological burden on those affected. While genetic factors and environmental stimuli are known triggers, another aspect is increasingly gaining scientific attention: the skin microbiome.
In recent years, studies have impressively demonstrated that the skin microbiome is significantly altered in people with atopic dermatitis. This microbial imbalance—also known as dysbiosis—contributes significantly to the development and worsening of symptoms. The following article examines in detail the differences between the skin microbiome of healthy people and that of people with atopic dermatitis, reveals scientifically based causes, and presents effective, microbiome-friendly care and treatment approaches.
What is the skin microbiome?
The skin microbiome refers to the totality of all microorganisms—bacteria, fungi, viruses, and mites—that live on our skin. This microbiotic ecosystem performs essential functions:
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It protects against pathogenic germs,
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regulates the skin's defenses,
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supports the skin’s barrier function,
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and maintains the slightly acidic pH value.
Healthy skin maintains a balance between beneficial and potentially harmful microorganisms. This balance varies from individual to individual, but remains relatively stable—as long as it isn't disturbed by external influences or disease.
Skin microbiome in healthy skin vs. atopic dermatitis
People with atopic dermatitis exhibit a significantly altered microbial composition on their skin compared to healthy individuals. Here is a table summarizing the most important differences:
| feature | Healthy skin microbiota | Skin microbiome in atopic dermatitis |
|---|---|---|
| Microbial diversity | High, diverse bacterial and fungal species | Greatly reduced, dominance of few species |
| Main bacterial species | Staphylococcus epidermidis, Cutibacterium acnes | Staphylococcus aureus, reduced diversity |
| pH value of the skin | 4.5–5.5 (slightly acidic) | Elevated, alkaline range |
| skin barrier | Intact, functional lipid layer | Disturbed, increased transepidermal water loss |
| immune response | Well regulated | Overactivated, inflammatory |
| Colonization by S. aureus | Rarely and in small quantities | Common, often dominant bacterial species |
These changes lead to a vicious circle: the disrupted skin barrier promotes the growth of harmful germs such as Staphylococcus aureus , which in turn promote inflammation and further damage the barrier.
The central role of Staphylococcus aureus in atopic dermatitis
A central problem in atopic dermatitis is the excessive colonization of the skin with Staphylococcus aureus . This bacteria is detectable in over 90% of atopic dermatitis sufferers – compared to only about 10–20% in the healthy population.
S. aureus produces toxins called superantigens, which trigger excessive activation of the immune system. This causes inflammation, itching, and further weakens the skin barrier. The germ also crowds out beneficial bacteria such as Staphylococcus epidermidis , which would normally produce anti-inflammatory substances and inhibit the growth of S. aureus .
Causes of microbial dysbiosis in atopic dermatitis
Genetic disposition
A large proportion of those affected carry mutations in the filaggrin gene, which is responsible for the production of structural proteins in the skin. A deficiency of filaggrin leads to impaired barrier function, which allows microbes to penetrate the skin more easily and destabilizes the balance of the skin's flora.
Excessive hygiene
The intensive use of soaps, disinfectants, and harsh cleaners can kill beneficial bacteria and reduce microbial diversity. Especially in children with atopic dermatitis, excessive hygiene can inhibit the natural development of the microbiome.
Environmental factors
Dry, heated air, air pollution, and climate change affect skin moisture and thus the living conditions of microorganisms on the skin. Frequent showers or baths with hot water exacerbate the problem.
Antibiotic therapies
Antibiotics—whether local or systemic—eliminate not only pathogenic germs but also protective skin bacteria. This makes way for resistant or aggressive pathogens, especially S. aureus .
Nutrition and gut microbiome
Current research shows that the gut microbiome is closely linked to skin health. Dysbiosis in the gut—for example, due to an unbalanced diet or medications—can promote systemic inflammation and negatively impact the skin microbiome.
Microbe-friendly care for atopic dermatitis: What really helps
1. Mild, pH-neutral cleansing
Use only soap-free wash lotions with a pH of 4.5–5.5. These support the natural acid mantle and promote the growth of beneficial bacteria. Look for products without fragrances, alcohol, and synthetic preservatives.
2. Prebiotic and postbiotic care
Prebiotics serve as "food" for beneficial skin bacteria. They help stabilize the balance and fight off harmful germs. Postbiotics—such as lactic acid or ferment extracts—have a direct anti-inflammatory and regenerative effect.
3. Fermented cosmetic products
Fermented ingredients such as Lactobacillus ferment or Bifida ferment lysates have been shown to promote a healthy skin microbiome, improve barrier function, and reduce skin redness. These products are ideal for sensitive skin types, such as those with atopic dermatitis.
4. Probiotics and symbiotics from within
Oral intake of probiotics (e.g., Lactobacillus rhamnosus GG) can have a positive effect on the immune system and skin health. Studies show that certain bacterial strains can reduce flare-ups of inflammation and strengthen the skin barrier.
5. Moisturizing care with skin-like lipids
Creams containing ceramides, phytosphingosines, and omega-3 fatty acids help repair the damaged skin barrier, thereby stabilizing the skin microbiome in the long term.
6. Reduction of trigger factors
Avoid excessive hygiene, excessive sweating, synthetic clothing, and stress—all of which can further destabilize the microbiome. Natural materials, cool showers, and relaxation techniques help soothe the skin.
Innovative approaches from microbiome research
In dermatological research, new therapies are emerging that specifically modulate the skin microbiome:
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Bacterial therapy: Initial clinical studies specifically use skin-friendly strains such as Staphylococcus hominis to displace S. aureus .
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Microbiome-based creams: Cosmetic manufacturers are developing products that contain live or inactive probiotic bacteria and specifically increase microbial diversity.
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Skin microbiome transplantation: A still experimental approach is the transfer of healthy skin flora to affected areas – similar to intestinal flora transplantation.
Conclusion: Neurodermatitis is also a microbial disease
The skin microbiome plays a key role in the development and treatment of atopic dermatitis. A disturbed skin flora—characterized by Staphylococcus aureus dominance and reduced diversity—leads to inflammation, barrier dysfunction, and chronic itching. This vicious cycle can be broken through targeted, microbiome-friendly skincare, probiotic approaches, and a holistic lifestyle.
For those affected, this means not just applying creams, but understanding and strengthening the skin ecosystem holistically – from the outside as well as the inside.
