A lotion containing specific bacteria kills a pathogen associated with an inflammatory skin disorder.

Atopic dermatitis causes dry, itchy and inflamed skin, and is often marked by high levels of the pathogenic bacterium Staphylococcus aureus. Other bacteria that normally live harmlessly on the skin are known to produce antimicrobial compounds, so Richard Gallo at the University of California, San Diego, and his colleagues set out to investigate whether these bacteria help to combat S. aureus. The researchers isolated and sequenced the genomes of a range of Staphylococcus species from the skin of both healthy people and those with atopic dermatitis. They found that people with the disorder had lower levels of microbes with antimicrobial activity than did their healthy counterparts.

The team identified several Staphylococcus species, and the peptides they make, that specifically kill S. aureus. Only the strains with antimicrobial activity were able to lower S. aureus levels when applied to people's skin.

Sci. Transl. Med. 9, eaah4680 (2017)