Here's the Real Reason Why Acne Covers Your Face

A study reveals that pimples appear to develop when the skin's microbiome — the overall balance of bacteria living on a person’s skin — gets out of whack.

Most of us — 80 to 85 percent of us, to be exact — have had acne at some point in our lives. Pimples can often erupt at inopportune times, such as during teen years before school photo shoots and important events, adding stress to already hectic lives. An entire industry caters to these insecurities, offering acne sufferers the supposed latest and greatest treatments, only for many users to find that these products do little to help.

Such treatments often target “acne-causing bacteria,” but new research has determined that the presence or absence of a particular bacterium does not trigger acne. Instead, the common skin condition appears to develop when its microbiome — the overall balance of bacteria living on a person’s skin — gets out of whack. 

The most surprising find of the research, presented today in Edinburgh at the Microbiology Society’s Annual Conference, is that the bacterium Propionibacterium acnes — long associated with acne, as its name suggests — is actually the most prevalent and abundant bacterial species in the facial hair follicles of people with clear, healthy skin.

Huiying Li, an associate professor of molecular and medical pharmacology at the David Geffen School of Medicine at UCLA and the study's co-senior author, even told Seeker that this bacterium may “play a role in defending against pathogens.”

This would mean that many current acne treatments could actually be killing off beneficial microorganisms.

Li, co-senior author Noah Craft, lead author Emma Barnard, and their colleagues conducted their research with objects that many of us are very familiar with: over-the-counter pore cleansing strips.

The researchers used these strips to obtain skin follicle bacterial samples from 72 individuals. Thirty-eight had acne, while the other 34 did not. The scientists then used a technique called DNA shotgun sequencing analysis to identify and compare the skin microbiomes of each group. Li and her team next analyzed the skin bacteria of 10 additional people, just to validate their earlier findings.

People with healthy skin were found to have bacterial communities enriched with genes related to bacterial metabolism.

The collection of genes, known as the metagenome, “reflects the sum of all the genomes of the species in the community,” Li explained. “We cannot pinpoint which species/strain has which gene, but we know what genes are enriched in the acne microbiome compared to the healthy skin microbiome.”

Related: Are Your Parents to Blame for Your Bad Acne?

Conversely, people with acne were determined to have higher levels of disease-associated genes, including those related to the production and transport of pro-inflammatory compounds, such as bacterial toxins that are potentially harmful to the skin.

No one bacterium seems to cause acne, according to the research, which was published in the journal Scientific Reports. Instead, genetic differences affecting various strains, and the overall composition of a bacterial community, appear to underlie the annoying disorder that can leave victims with lasting scars — both physical and emotional. 

“It is believed that multiple factors play a role in acne, including hormone levels, follicle structures, and the skin microbiome," Li said, explaining why some people experience periodic microbiome imbalances. "We don’t know if acne could be contagious, but transmission of microbes from person to person can happen.”

It is further suspected that reduced secretions of sebum, an oily substance that naturally moisturizes skin and hair, could help to prevent acne eruptions. Since sebum levels tend to lower with age, the researchers believe this tendency could explain why people over 50 rarely get acne. The downside is that these individuals often have drier skin, requiring the application of moisturizers. 

Related: The Truth About Anti-Aging Creams

For those who cannot wait for age to possibly clear up their acne, Li and her team suggest that “new therapies can be personalized and targeted approaches based on the individual microbiome; restoring a balanced microbiome through applications, such as potential topical probiotics and/or phages.”

Phages are viruses that can attack and destroy specific bacterial strains, while leaving the beneficial ones intact.

The envisioned treatments follow a trend of more personalized medicine, rather than a “one size fits all” approach. This basic method could apply to serious illnesses, such as meningitis. Up to 35 percent of us harbor the bacterium Neisseria meningitides, associated with the illness, yet only a fraction develop meningitis. Changes to the individual’s overall microbiome, immunity and other factors could therefore once again lead to harmless bacteria going bad.

Other animals, such as dogs, can get meningitis. Humans are the only known animals to suffer from acne, though.

That's just our luck.