Agr virulence is critical for epidermal colonization and associates with atopic dermatitis development.

Atopic dermatitis (AD) is commonly associated with colonization by in the affected skin. To understand the role of in the development of AD, we performed whole-genome sequencing of strains isolated from the cheek skin of 268 Japanese infants 1 and 6 months after birth. About 45% of infants were colonized with at 1 month regardless of AD outcome. In contrast, skin colonization by at 6 months of age increased the risk of developing AD. Acquisition of dysfunctional mutations in the Agr quorum-sensing (QS) system was primarily observed in strains from 6-month-old infants who did not develop AD. Expression of a functional Agr system in was required for epidermal colonization and the induction of AD-like inflammation in mice. Thus, retention of functional virulence during infancy is associated with pathogen skin colonization and the development of AD.