Preventing and Treating Skin Injuries

Expert Q&A: Explore why the skin’s delicate ecosystem depends on a healthy microbiome

Dr. Cassandra Quave explains the science behind the skin microbiome

Dr. Cassandra Quave in her lab talking about skin microbiome.

Haven’t heard of the skin microbiome? You will. In this interview, Dr. Cassandra Quave, Assistant Professor of Dermatology and Human Health at Emory University and Medline consultant, explains the impact of the skin microbiome and what’s being done to better understand it.

Q: What is the skin microbiome?
A: If you visualize the microbiome as an ecosystem, you can think of the skin as having different environmental characteristics depending on its location on the body. For instance, the forearm would be a human dry desert, and areas with skinfolds (e.g. the armpit or groin) a hot, wet jungle.

Some factors that affect the microbiome:

  • pH levels
  • humidity
  • temperature
  • light exposure
  • salinity
  • a host’s gender
  • genotype
  • immune status
  • cosmetic use

Most microbes found on or in the body are not harmful and very few are pathogenic. However, opportunities exist for them to become pathogenic. For example, Propionibacterium acnes (acne) and Staphylococcus epidermidis are both part of the normal skin microbiome. But if either attaches to a wrong habitat (e.g. an implanted medical device such as an IV catheter or joint replacement), it can cause problems.

We can distinguish between an infection and normal skin microflora because an inflammatory skin disease is usually associated with heavy microbial load. If you look at the microbial makeup of an eczema flare site, for example, it’s densely populated with Staphylococcus aureus. However, we still don’t know what kickstarted the problem—the disease, the problems, or mutations within the host or bacteria.

Q: Why does the skin microbiome matter to wound care?

A: The microbiome plays a role in the health of the skin environment of patients, so the wound bed microbiome is an area of medical relevance. Some wounds are hard to heal in part because of the presence of certain microbes, such as Pseudomonas or Staphylococcus. They can prevent epithelization or wound healing in the wound bed.

Other microbes that aren’t affiliated with the wound but that may be linked to inflammatory skin diseases can cause discomfort in patients. The itch from eczema is a prime example. The microbiome of the wound bed differs from normal skin in that it tends to be a dysbiotic—or imbalanced—environment, where a few species predominate and can cause a lot of harm. For therapeutic development, we’re always thinking about how we can weaken their hold in that environment. How do we create a shift in that ecosystem that could facilitate better wound healing?

Historically, we’ve been limited in our ability to grow and culture microbes in the laboratory, but there’s been progress as the Human Microbiome Project is using genome sequencing to evaluate the makeup of different microbes in different body sites.

Q: What do we know about microbiomes?

A: Scientists and the medical community are aware that humans are literally coated in microbes, both inside and out. Just like with the gut microbiome, an imbalance in the resident microflora can lead to different types of disease outcomes. In the skin environment, if you have an out-of-balance situation with microbes, you’re likely to have an inflammatory response. Maintaining proper balance in your skin microbiome is very important.

Microbes living in the wound bed environment play a big role in determining success or failure of wound management therapies.

Just as scientists know that the composition or makeup of that microbial mixture varies among different parts of the body, they also know that it varies slightly from person to person. That can be due to one’s age or stage of life. Going through puberty and having oily skin can foster the growth of microbes like Propionibacterium acnes, which like to grow in an anaerobic, or oxygen-free, environment.

Q: Is it possible to balance an out-of-balance microbiome?

A: That’s the billion-dollar question. I don’t know if anyone has that answer yet. We’re just starting to literally scratch the surface in understanding that. Just like the gut microbiome, we still don’t have an optimal composition for the skin microbiome. We do know that when you have a reduction in diversity—when you see a shift from many different types of microbes down to very few in a skin site—that is a signal of disease. Diversity is good; skewing the balance of the population to a few or even a single species can be very bad. Microbes living in the wound bed environment play a big role in determining success or failure of wound management therapies.

We’re learning more each day on how to restore balance in the skin microbiome.

While there is still much to be learned about the skin microbiome, identifying it is nonetheless an important breakthrough. Medline Skin Health is dedicated to bringing you the latest information and resources in skin health science and discoveries.

In addition to her work with the skin microbiome, Dr. Quave also shares her expertise about the importance of skin care in overall skin health. Be sure to check out her insights in her recent webinar, The Impact of Botanicals on Skin Health.

Headshot of Dr. Cassandra Quave.

Cassandra L. Quave, PhD, is curator of the Emory University Herbarium and Assistant Professor of Dermatology and Human Health at Emory University, where she leads drug discovery research initiatives. She is a clinical consultant to Medline Industries.

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