The Skin Microbiome: Dermatologic Insights

Dr Hilary Baldwin discusses how evolving insights into the skin microbiome are reshaping the understanding of acne, eczema, rosacea, and other inflammatory skin diseases. Learn why barrier repair remains central to microbiome health, how probiotics and postbiotics may fit into future dermatologic care, and why personalized approaches are essential as microbiome science continues to evolve.

Transcript

Hello, I'm Hilary Baldwin. I run the Acne Treatment and Research Center in Brooklyn, New York, and it's a pleasure to be talking about the skin microbiome today at SCALE. 

What are the most important recent insights into the skin microbiome that are changing how we understand common dermatologic conditions?

Dr Baldwin: The microbiome is a very trendy topic. It's trendy for everyone. It's trendy for industry. It's trendy for our patients Everybody wants to know about it and it's just a it's a big topic to talk about. Even, if you look on the internet you can even find a microbiome protecting dog food from Purina. So, this is very far-reaching and the problem is that our excitement and our interest in the microbiome, I think, has exceeded the development of data to support how we're going about it what we're using and when we're using it and what sort of conditions we expect it to be able to treat. So, one of the problems, of course, is the microbiome is different for every person on the planet. So, it's not like one size is going to fit all. Studies have been done that show that even in specific locations like the axilla or the foot, that, 4 people, with the evaluation of the bacteria that's on there -- completely different. It differs by age, it differs by gender, it differs by race, and it differs by where you happen to be located. If you're in farming country, part of your microbiome, frankly, is cow poop and the bacteria that are in cows and sheep. And if you live in an urban area, it includes pollutants and toxins from the environment and from factories, for example. So since nobody's microbiome is like anybody else's and the microbiome of the foot is different from the face, is different from the axilla. very difficult to talk about the microbiome in general. And it's also difficult to say, therefore, this one bacterium in this cream is going to do the trick for anything other than a single condition in a single person on a single location. So what recent data do we have? The data that we have is that we're kind of in the dark here. Probably the best thing to be doing is to pick a probiotic that has numerous different bacteria in it because we don't know which one is appropriate. But more importantly, to be protecting the barrier function. The barrier and the microbiome go hand in hand. When one of them is ill, the other one is ill as well. And the inverse is true as well. If you make the barrier better, the microbiome will follow and vice versa. So I think the easiest thing to do and the thing for which we've got lots of data is to repair the barrier and let the microbiome be what it is in a particular person at a particular time. 

How can clinicians practically support or restore microbiome balance when managing conditions like acne, eczema, or rosacea?

Dr Baldwin: So I think the best way for us to think about the microbiome in terms of specific disease entities is to fix the barrier, especially with atopic dermatitis. Atopic dermatitis has clearly been shown to be a barrier dysfunction disorder with a concomitant microbiome disruption, namely an increase in staph aureus. So if you fix the barrier, the staph aureus concentration decreases and healthy skin follows suit. So I think even with acne and with psoriasis and other conditions that have a component of barrier disruption, the trick, since we're not quite sure which bacterium to use, is to repair the barrier and let the microbiome do what it needs to do. We have to remember, of course, that when treating atopic dermatitis or when treating acne, we're using medications that disturb the microbiome. We're using topical steroids. We're using benzoyl peroxide and clindamycin in our acne patients, which are making a mess of the microbiome. So are topical retinoids. So is isotretinoin, dramatically changing the barrier, dramatically changing the microbiome. So it's not necessarily a bad thing to temporarily mess with the microbiome because it makes the disease better, which makes the barrier better. which makes the microbiome go to the normal state for that individual in that particular location. 

What role do emerging therapies—such as probiotics, postbiotics, or microbiome-targeted topicals—play in the future of dermatologic care?

Dr Baldwin: So one of the most difficult questions I think is what is the role of picking a specific probiotic or a specific pre or a specific postbiotic to treat an individual with a particular condition? Because again, the data just isn't there. I personally go more with the prebiotic concept. The prebiotics, of course, are helping the microbiome to be its healthiest state. And the most sensible prebiotic for us to use is a quality moisturizer. Because once again, repairing the barrier with the quality moisturizer is going to help the microbiome. So what's a quality moisturizer? It contains a humectant to draw in, attract, and hold on to water. An occlusive to seal that water in. An emollient to help seal the water in as well, but to make the skin soft and supple. Maybe throwing in physiologic lipids like ceramides and cholesterol, especially important, of course, in atopic dermatitis. Maybe some anti-inflammatories like niacinamide. and all of course keeping the pH nice and low to repair the barrier to maintain a healthy barrier as a prebiotic and then the microbiome will follow suit. Now postbiotics are interesting, actually to me much more interesting than probiotics. Probiotics, the bacterium needs to be kept alive so it needs to be refrigerated maybe or it needs to, the product can't contain preservatives because they would kill the the probiotics. Postbiotics are heat-killed bacteria. And they're metabolic byproducts. So you get all of the benefits of a probiotic, but you can put it into a powder. You don't have to refrigerate it. And you don't have to add preservatives that might kill the bacteria, but will keep the product itself from growing a bacterium. So much easier to use, probably healthier, probably safer, and certainly better for mass production and shelf life. So I think we're turning more to postbiotics in recent past, vitreoscilla filiformis, for example, in atopic dermatitis, particularly useful in several studies. So I think that's probably where the future lies. 

Are there any tips or insights you would like to share regarding maintaining a healthy microbiome?

Dr Baldwin: So maintaining a healthy microbiome is different for every person and every condition and every location on the body. So the easiest thing to do and the most sensible thing to do is to repair the barrier in those locations. So that the microbiome becomes the healthiest for that particular person in that particular area. Until, of course, we have more data that shows us that this particular bacterium is useful for this treatment of this particular