Good Bacteria Associated with Acne-free Skin

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Researchers from the University of California, Los Angeles (UCLA), Washington University in St. Louis and the Los Angeles Biomedical Research Institute have discovered that acne bacteria, which thrive in the oily pores of skin, consist of “bad” strains associated with pimples and “good” strains that may protect the skin and keep it healthy. The finding may help dermatologists develop new, strain-specific treatments for acne. The research is published in the Journal of Investigative Dermatology.

Acne bacteria

The human skin and digestive tract are literally crawling with bacteria, some pathogenic (disease-causing) and some harmless. In recent decades, researchers have begun to study the role of beneficial bacteria — such as the Lactobacillus acidophilus that’s found in a healthy human gut — that aren’t just harmless, but are actually protective. In the digestive tract, pathogenic bacteria have to compete for resources, including nutrition, like any other species on Earth. If there are lots of non-pathogenic bacteria like P. acidophilus present, they make it harder for the pathogenic strains to colonize the gut and cause infection.

New research suggests that a similar dynamic may be playing out on the surface of the skin, and that protective bacterial strains on an individual’s skin may reduce the likelihood of acne. Though scientists have known for quite some time that the development of acne is an infectious process — it’s mediated by bacteria, which is why cleanliness is so important and why severe cases can be treated with antibiotics — the specific strains involved and the mechanism by which they cause infection aren’t well understood. A research team led by Dr. Huiying Li at the University of California, Los Angeles, examined the skin of both acne sufferers and those with clear complexions in an attempt to catalogue microbial populations. What they found intrigued them.

The species Propionibacterium acnes has long been associated with development of facial blemishes, but Li’s team found scores of strains of P. acnes, many of which were previously unknown. Even more interesting, two particular strains were found almost exclusively on the faces of individuals with blemished skin, while a third strain was largely limited to those with clear skin. The team hypothesizes that the strain associated with clear skin — called P. acnes RT6 — may actually be fighting acne-causing strains such as the two found on the skin of those with blemishes.

While this hypothesis is an interesting one and certainly warrants further research, it’s important to remember that the data gathered through this research are correlational rather than causal. In other words, it’s not yet scientifically reasonable to conclude that the RT6 strain fights acne-causing bacteria, and therefore supplemental RT6 would benefit those with acne. Further experimentation may eventually allow this conclusion, however. Should more research show that RT6 is indeed protective, it’s possible that it might be beneficial when used as a probiotic supplement, similar to L. acidophilus. Even more to the point, it could be that antibiotics will eventually be abandoned as a treatment for acne, on the grounds that killing all bacteria, including the “helpful” ones (such as P. acnes RT6, should it prove to be beneficial), is not the best way to treat acne.


  1. Fitz-Gibbon et al. Propionibacterium acnes strain populations in the human skin microbiome associated with acne. J Invest Dermatol. 2013 Jan 21. doi: 10.1038/jid.2013.21.
    View abstract
About the Author

Kirstin Hendrickson, Ph.D., is a science journalist and faculty in the Department of Chemistry and Biochemistry at Arizona State University. She has a PhD in Chemistry, and studied mechanisms of damage to DNA during her graduate career. Kirstin also holds degrees in Zoology and Psychology. Currently, both in her teaching and in her writing, she’s interested in methods of communicating about science, and in the reciprocal relationship between science and society. She has written a textbook called Chemistry In The World, which focuses on the ways in which chemistry affects everyday life, and the ways in which humans affect each other and the environment through chemistry.