Bacteria-containing skin cream kills pathogen

Bacteria-containing skin cream kills pathogen

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

Atopic dermatitis (AD) 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 researchers 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 coagulase-negative Staphylococcus (CoNS) species, and the peptides they make, that specifically kill S. aureus. The antimicrobial activity was identified as previously unknown antimicrobial peptides (AMPs) produced by CoNS species including Staphylococcus epidermidis and Staphylococcus hominis.

These AMPs were strain-specific, highly potent, selectively killed S. aureus, and synergized with the human AMP LL-37. Application of these CoNS strains to mice confirmed their defense function in vivo relative to application of nonactive strains.

Strikingly, reintroduction of antimicrobial CoNS strains to human subjects with AD decreased colonization by S. aureus. These findings show how commensal skin bacteria protect against pathogens and demonstrate how dysbiosis of the skin microbiome can lead to disease.