The Skin’s Ecosystem: Could Bacteria Become the Next Treatment for Eczema?

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“I can't seem to remember a day when I had zero discomfort. Even when my skin starts to heal, it's not a quick process.” 

For 37 years, discomfort is all Patient A knows about her everyday life. To protect her privacy, the individual interviewed for this article requested to remain anonymous and will be referred to as Patient A.

Patient A followed the typical advice given to people struggling with eczema: avoid irritants, practice good skin hygiene, moisturize, medication, etc. 

“You know, sometimes there are days where I wish I didn’t have to look for cotton materials for clothes or blankets. Sometimes I want to use certain fragrances, I can’t”

Hearing about Patient A’s sensitivity to everyday material, it raised a question: What causes certain substances to trigger such a strong reaction in people with eczema?  

Patient A had a general idea.

“I know it has something to do with my immune system and how it’s weaker or more sensitive—one or the other,” she said.

It is a common misconception that people with eczema automatically have a weak immune system. However, it is true that the immune system often overreacts. People with eczema can have either healthy or immunodeficient immune systems. What happens is the opposite of what the skin is known for: protection, yet, the skin barrier allows unwanted germs, allergens, etc to go into the skin. Once this happens, the immune system reacts and ultimately causes skin inflammation. On the other hand, moisture and other nutrients for the skin seep out.

“I recently found out that bacteria could potentially help treat eczema”

“Really? Bacteria can actually help with eczema? I would’ve thought it would make it worse.”

Naturally, bacteria are seen as threats, so the idea that bacteria that naturally live on the skin could play a protective role and even become part of a future treatment for eczema seemed almost counterintuitive.

Many people think of eczema as simply a skin condition. However, according to dermatologist and microbiome researcher Dr. Richard Gallo, the disease involves a much more complex interaction between the immune system, the skin barrier, and the skin’s ecosystem. 

“How do you think the public misunderstands the relationship between the immune system, the skin barrier, and the microbiome?”

“One of the things that perhaps people overlook is that the skin is constantly talking with the outside environment. Unlike internal organs, the skin is continuously exposed to sunlight, chemicals, detergents, humidity, and countless microorganisms. Many people think bacteria are always just bad. And what we've learned is that many bacteria are not only not bad, but they are actually essential for health,” answered Dr. Gallo

Bacteria have always carried a negative connotation, where people usually associate them with illness. Advertisements for sanitizing products promising to kill 99.9% of germs further support the idea that bacteria are the enemy and something to fear. Yet new research suggests that some bacteria may be among our strongest allies. Scientists are beginning to discover that the skin is a living ecosystem. Bacteria have always coexisted with cells, often in mutualistic relationships. On top of that, it has come to be understood that some bacteria play a critical role in maintaining healthy skin.

This relationship is interesting because the skin is also designed to defend the body against harmful bacteria. Skin cells produce antimicrobial peptides, small molecules that inhibit or kill bacteria. It is an innate immune defense to protect humans. At the same time, large amounts of bacteria live on the skin and are more beneficial than most may think. Some bacteria are known to prevent colonization of harmful bacteria.

“Many people refer to the skin as an ecosystem. Why is that?” I asked

Dr. Gallo explained, “What an ecosystem means, you know, lots of different elements of the overall ecology working, hopefully, in balance. So you think about a rainforest, you need a certain amount of rain, you need a certain amount of sunlight, you need nice soil. 
You need the plants, you need the animals, you need the insects. They all work together and balance things out, and the skin is exactly the same way. We have the natural antibiotics, we have the physical barrier, a chemical, and oils on our skin. 
And then that skin is expecting to be in the air, you know, not underwater. It's a balance with the humidity of the atmosphere.” 

A similar relationship exists on the skin, where good bacteria compete for space and defend via immune communication, how your good bacterias and white blood cells talk to each other, to lessen the harmful bacteria's opportunities to grow which ultimately keeps the skin healthy. 

This raised an important question. If the skin is continuously producing antibodies designed to kill bad bacteria, how do the good bacteria continue to live there? Dr. Gallo's team began exploring whether some bacteria might actually provide benefits to their human host.

One of the major villains in eczema research is a bacterium called Staphylococcus aureus. This microbe is notorious for causing serious infections and includes antibiotic-resistant strains such as MRSA. MRSA, a bacterium that is resistant to many common antibiotics, is an abbreviation for methicillin resistance… It's one of the leading causes of death in our nation. It causes very, very serious infections, not only of the skin, but it can get into your blood and kill you. And what we learned is that our natural antibiotics try to kill those bad bacteria. 
But sometimes they're not enough, and they also rely on the good bacteria that produce their own antibiotics to kill Staphylococcus.” Dr. Gallo discovered

In other words, some bacteria help protect humans from other bacteria. The skin's microbial community functions less like a combat zone and more like a delicately balanced ecosystem, where different organisms influence one another.

“What’s going on with the ecosystem with eczema?” I asked

“When you see eczema, at that point, the physical and chemical barrier of the skin surface is changed. And that leads to an environment where the bacteria change too. And what often happens is the bacteria will have an imbalance, so sometimes there are more bad bacteria. 
And then the bad bacteria feed back and start to then damage that skin even more. So you get a cycle, so the whole ecology is thrown amok, and the disease gets worse,” Dr. Gallo replied.

When these parts remain balanced, the skin functions effectively. When that balance is disturbed, problems arise. Eczema is a result of what happens when this ecosystem falls out of balance.

Because eczema involves so many interconnecting factors, scientists debate where the disease truly begins. Is it primarily an immune system disorder? A skin barrier disorder? Or a microbiome disorder? Dr. Gallo argues that these questions could oversimplify the problem. Rather than existing as separate causes, these factors form a circle where “you could start on this circle with having a mutation in something that affects your immune system. That can start it. 
Or you're, you can start with a mutation in something in your skinned physical barrier, things that the human genes might make. But you can also start on a circle with those bad bacteria, maybe getting exposed early in life to the wrong type of environment. And they make the immune system work crazy, and then the barrier breaks down. 
So you can begin anywhere on that circle. Once you enter it, it's hard to get out of it. So, because it's a circle, eventually, it touches on the microbiome.”

The skin barrier is a multi-layered defense system, utilizing physical barriers against larger threats and chemical barriers like oil and sweat to repel pathogens. During an eczema flare, both the skin's physical and chemical barriers become damaged. This altered environment changes which microbes can survive on the skin. Harmful bacteria may become more abundant, allowing harmful bacteria to become more dominant. The increased number of harmful bacteria can further damage the skin, triggering a self-reinforcing cycle. The weakened skin barrier allows microbial imbalances to develop, and those imbalances worsen the skin damage. 

This understanding has inspired researchers to explore a possibility: what if eczema could be treated by restoring beneficial bacteria?

The concept resembles probiotics for the gut but applied to the skin. Researchers are investigating whether beneficial bacteria can be added directly to the skin to suppress harmful microbes and restore balance. To some people, the idea may appear futuristic. However, according to Dr. Gallo, this treatment is already becoming reality. His team is currently conducting large clinical trials with supporting facts by the National Institutes of Health, to evaluate scientifically designed microbiome-based treatments. Rather than adding random bacteria, researchers are identifying specific microbes and uncovering exactly how they interact with the skin and immune system. 

Technological advances have played a key role in making this research possible. One major breakthrough, as Dr. Gallo explained, “was the ability to sequence the DNA of the microbes on the surface of the skin,” which allowed researchers to “look at many different types of microbes at the same time.” However, identifying these microbes is only part of understanding the skin microbiome. By combining DNA sequencing with biochemistry, cell biology, and immunology, researchers can investigate not only which microbes are present, but also what they are doing and how they interact with the skin and immune system.

Another possibility is the development of personalized microbiome therapies. Dr. Gallo described clinical studies in which researchers analyzed an individual's skin microbiome and identified the most beneficial bacteria for that specific patient. These personalized approaches provide promising results in reducing harmful bacteria, improving the skin barrier function, and other ways of protecting the skin. Dr. Gallo mentioned that they had performed a clinical trial where “[they] screened individual patients' microbiome to find out what the best bug for them would be. And that worked really, really well. The problem is, it's very time-consuming, and there's a lot of effort that goes into that. So it's hard to sort of develop that as a treatment for many people, like one million people.” 

Another reason why these take longer to develop is that “the biggest risk is are you putting a bacteria that could be dangerous on the skin when you're doing it? So researchers and doctors] really have to know what [they are] doing, because bacteria… if they overgrow, they can, they can hurt [patients]. 
So [specialists] really need to know what you're doing and what kind of microbes you're using.” Future technological improvements may eventually make personalized microbiome medicine more practical on a larger scale.

Despite the excitement surrounding microbiome therapies, Dr. Gallo reiterates the importance of caution. Manipulating microbial communities is not without risk. Researchers must ensure that any bacteria introduced onto the skin are safe and will not become harmful if they grow excessively. Furthermore, Dr. Gallo also warns that some companies have already begun marketing microbiome products with claims that exceed the available scientific evidence. Consumers should consider such products carefully and rely on treatments supported by rigorous research.

Another common misconception after learning about the benefits of bacteria is regarding cleanliness. If beneficial bacteria are important, should people stop washing their hands or bathing regularly? Dr. Gallo says the answer is far more nuanced. Excessive use of harsh detergents, antiseptics, or antibiotics can disrupt beneficial microbial communities. However, hygiene practices remain important for preventing the spread of dangerous pathogens. Handwashing continues to be one of the most effective public health measures ever developed. The problem lies in maintaining a healthy microbial community while controlling harmful organisms. 

For people with eczema, these new findings bring hope. Most current treatments focus on reducing inflammation or calming the immune system after symptoms start. Microbiome therapies offer a deeper approach, aiming to target root causes and restore the skin’s natural equilibrium. 

Dr. Gallo is taking a step further in his interest in studying newborns to research on how early exposure to microbes affects health later in life. His goal is not just to treat, but to prevent eczema altogether.

Scientists are recognizing that skin health is not just the absence of bacteria but the presence of balance. The future of eczema treatment is not about getting rid of all bacteria but rather learning which bacteria should be part of the skin’s ecosystem and nurturing them safely. By doing this, researchers might change the old belief that bacteria are always our enemies. For people with eczema, these tiny organisms could become some of their best allies. †

Written by Staff Writer Kathleen Cheng (kac071@ucsd.edu) 

References

Centers for Disease Control and Prevention. “About Handwashing.” Clean Hands, U.S. Centers for Disease Control and Prevention (CDC), 16 Feb. 2024, https://www.cdc.gov/clean-hands/about/index.html.

Cleveland Clinic. “Eczema in Adults and Children.” Cleveland Clinic, 25 Oct. 2022, https://my.clevelandclinic.org/health/diseases/9998-eczema.

“Methicillin-Resistant Staphylococcus Aureus (MRSA).” Cleveland Clinic, 7 May 2024, https://my.clevelandclinic.org/health/diseases/11633-methicillin-resistant-staphylococcus-aureus-mrsa.

“Eczema Treatments.” National Eczema Association, 21 Mar. 2025, https://nationaleczema.org/treatments/.

Kim, Byung Eui, and Donald Y. M. Leung. “Significance of Skin Barrier Dysfunction in Atopic Dermatitis.” Allergy, Asthma & Immunology Research, vol. 10, no. 3, 2018, p. 207, https://doi.org/10.4168/aair.2018.10.3.207.

Xia, Jingjing, et al. “Redefining the Skin Barrier: A Microbiome‐Integrated Multilayered Defense Model.” Barrier Immunity, July 2025, https://doi.org/10.1002/dni2.70002.