Teen skin bacteria could hold the secret to acne prevention

Acne, eczema, and other skin conditions are issues that manifest on the surface, but they’re closely tied to what’s living just beneath. Bacteria on our faces aren’t just passive passengers. They interact, compete, and sometimes even fuel disease.

Two major bacterial species – Cutibacterium acnes and Staphylococcus epidermidis – dominate most people’s facial microbiome. Yet, figuring out how they behave and change over time has long been a challenge.

Shaping the skin’s future health

Researchers at the Massachusetts Institute of Technology have now mapped out the behavior of skin bacteria in more detail than ever before.

Their work offers a clearer picture of when new strains appear, how long they stick around, and how this timing could shape future acne treatments.

The research also points to a crucial discovery: the early teen years may be a key time in which to shape the skin’s future health.

Teenage skin and the rise of acne bacteria

The team found that most new C. acnes strains – the ones commonly linked to outbreaks of acne – appear during the early teenage years.

But after that, the bacterial community on the face becomes incredibly stable. Even when people come into contact with new strains, they rarely take hold.

That insight has major implications. “We found that there are some surprising dynamics, and these dynamics provide insights for how to design probiotic therapy,” said Tami Lieberman, senior author of the study.

“If we had a strain that we knew could prevent acne, these results would suggest we should make sure we apply them early during the transition to adulthood, to really get them to engraft.”

Tracking skin bacteria and acne

To understand these microbial patterns, the researchers studied the skin of 30 children and 27 of their parents, all from the same Boston-area school community.

Sampling family members helped the team to see how strains pass between people and how stable – or unstable – those strains really are.

Some participants were sampled more than once, allowing the scientists to track bacterial changes over time.

From each skin swab, they grew bacterial colonies and sequenced the DNA of individual cells. This helped them measure the number of different lineages in each person, how long each had been around, and how they changed over time.

They found 89 lineages of C. acnes and 78 of S. epidermidis. Up to 11 of each could be found on a single person. The findings surprised the team, as earlier studies had suggested these communities remained mostly unchanged over time.

“We wanted to know if these communities were truly stable, and if there could be times where they weren’t stable,” Lieberman explained. “In particular, if the transition to an adult skin-like microbiome would have a higher rate of acquisition of new lineages.”

An ideal environment for skin bacteria

Teenage years come with a spike in oil production on the face, which provides an ideal environment for bacteria.

Previous studies have shown a 10,000-fold increase in bacterial density during this period. The current study confirmed that while adult facial microbiomes are largely stable, the early teen years offer an opportunity for new strains of skin bacteria – particularly of C. acnes – to establish themselves.

“For C. acnes, what we were able to show was that people do get strains throughout life, but very rarely,” said Lieberman. “We see the highest rate of influx when teenagers are transitioning to a more adult-like skin microbiome.”

This supports the idea that acne-related probiotics might be most effective when used early, during the teenage transition.

Different bacteria, different timelines

The team also found that S. epidermidis is far more volatile than C. acnes. On average, each strain of S. epidermidis sticks around for less than two years.

However, even family members living together often didn’t share the same lineages. This implies that bacteria aren’t constantly passed back and forth, and that the skin might be more selective than expected.

“That suggests that something is preventing homogenization between people,” said Lieberman. “It could be host genetics or host behavior, or people using different topicals or different moisturizers, or it could be active restriction of new migrants from the bacteria that are already there at that moment.”

Future research directions

The researchers now want to know whether the immune system reacts differently depending on when a person first acquires a new strain of C. acnes. They also hope to understand why individual microbiomes remain so distinct, even when people are exposed to each other’s bacteria daily.

“We want to understand why we each have unique strain communities despite the fact that there is this constant accessibility and high turnover, specifically for S. epidermidis,” said Lieberman. “What’s driving this constant turnover in S. epidermidis, and what are the implications of these new colonizations for acne during adolescence?”

While there’s still a lot to learn, one thing is clear: the story of skin bacteria starts early. And the choices we make – or don’t make – during our teenage years might leave a lasting mark.

The full study was published in the journal Cell Host & Microbe.

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