Here’s What’s Really Behind Your Acne Breakouts

About 85% of people get acne at some point in their lives, and scientists have long blamed it on the bacterium Propionibacterium acnes. But so-called P. acnes never entirely explained acne, because research has shown that it’s abundant in hair follicles of people with clear skin, too—not just those with pimples.

Now, new research puts forth a different potential acne culprit: an imbalance of bacteria living on the skin. The findings, presented recently at the Microbiology Society’s Annual conference and published in the journal Scientific Reports, suggest that balancing bacteria—not wiping it out, as antibiotic treatments do—may be one future way to battle breakouts.

UCLA researchers used pore cleansing strips to gather skin samples from 38 adults with acne and 34 people without it. They then used DNA sequencing to analyze and compare the bacterial makeup of the two groups.

“This allowed us to look not only at what species of bacteria were there, but also at their genomic content to see what kinds of genes they had,” says study author Dr. Huiying Li, an associate professor of molecular and medical pharmacology at the David Geffen School of Medicine at UCLA.

The researchers found that P. acnes strains were prevalent in both groups. But they identified some small genetic differences: In the acne-free group, the skin microbiome was enriched with genes related to bacterial metabolism, a process that’s thought to prevent harmful bacteria from colonizing.

The group with acne, on the other hand, had higher levels of genes involved in the production and transport of bacterial toxins and other pro-inflammatory compounds.

Li says that the makeup of bacteria in skin follicles seems to reflect and influence whether skin is clear or blemished. “You may have the bad bacteria, but if you also have good ones in the same community that can counterbalance the bad guys, you may not have acne,” she says.

The researchers were able to predict whether a person had acne or not based solely on their bacterial makeup, with about 85% accuracy. The study was small, but that predictive power remained when they analyzed samples from an additional 10 volunteers.

The study suggests that balancing the skin’s microbiome may be a better way to treat acne than the current use of antibiotics, which can contribute to antibiotic resistance. It’s not yet clear how to do this, but probiotic supplementation and phage therapy—the use of viruses to attack specific bacterial strains—may be two possible ways, Li says.

“Everybody has P. acnes, and some P. acnes are good, in general, for our skin,” says Li. “We need to figure out how to selectively get rid of the bad ones but keep the good.”