Harmless bacteria kills acne

A harmless virus living on the skin naturally seeks out and kills the bacteria that cause pimples and acne, U.S. researchers say. Principal investigator Dr. Robert Modlin of the David Geffen School of Medicine at University of California, Los Angeles, and colleagues at the University of Pittsburgh looked at two microbes that share the name: Propionibacterium acnes, a bacterium thriving in our pores that can trigger acne, and P. acnes phages, a family of viruses that live on human skin. The viruses are harmless to humans but are programmed to infect and kill P. acnes bacteria, Modlin said. When P. acnes bacteria aggravate the immune system, it causes the swollen, red bumps associated with acne and the effective treatment works by reducing the amount of P. acnes bacteria on the skin. "We know that sex hormones, facial oil and the immune system play a role in causing acne; but, a lot of research implicates P. acnes as an important trigger," first author Laura Marinelli, a UCLA postdoctoral researcher in Modlin's laboratory, said in a statement. "Sometimes they set off an inflammatory response that contributes to the development of acne." Using over-the-counter pore-cleansing strips, the researchers lifted acne bacteria and the P. acnes phages from the noses of both pimply and clear-skinned volunteers. When the team sequenced the phages' genomes, they discovered the viruses possess multiple features that make them ideal candidates for the development of a new anti-acne therapy, the researchers said. The findings were published in the journal mBio.