Shifts in infant skin microbiome at 2 months after short-term emollient use from birth are associated with reduced prevalence of atopic dermatitis at 12 months in a high-risk cohort

The rising incidence of atopic dermatitis (AD) prompted research into potential risk factors (Paller et al, 2024). Although family history and genetic factors, notably mutations of the FLG gene and others, are key (Palmer et al, 2006), the role of the skin microbiome as an early risk factor is poorly understood, despite its well-known role once the disease has been established (Demessant-Flavigny et al, 2023; Kong et al, 2012). Although early-life Staphylococcus aureus dominance is suspected to associate with future AD manifestation (Meylan et al, 2017; Rapin et al, 2023), controversies exist regarding S aureus as a definitive biomarker due to timing, specificity, and strain variability concerns (Byrd et al, 2017; Kennedy et al, 2017). We recently demonstrated in a randomized controlled clinical trial (STOP AD [Short-term Topical Application for Prevention of Atopic Dermatitis]) that very early initiation of short-term emollient use reduced the incidence of AD in the first year of life in infants with family history of atopy (Ní Chaoimh et al, 2023). The purpose of this study was to identify patterns in the skin microbial community of infants at 2 months postpartum that associate with higher risk of developing AD within the first year. We also examined the relatedness of such changes to the FLG genetic background and explored the potential association of microbiome patterns with the preventive initiation of emollient use.