Strain-Specific Responses Drive Acetamiprid-Induced Changes in a Cutaneous Bacterial Community In Vitro

Our skin is colonized by the skin microbiome and provides a physical, chemical, and metabolic barrier to the environment. Although current evidence links dietary pesticide exposure to microbiome disturbance and adverse health effects, the corresponding effects of dermal pesticide exposure on the skin microbiome remain largely unexplored and require further investigation. Using a skin-derived ten-strain model community and the corresponding single-strain cultures, we assessed the impact of the insecticide acetamiprid (ACE) in vitro. We identified strain-specific responses that shaped community-level outcomes. Exposure to ACE significantly altered the growth kinetics, metabolite profiles, and composition of the bacterial community. The most pronounced response was observed for Acinetobacter radioresistens, which exhibited marked growth inhibition upon ACE exposure, resulting in its complete loss from the community. At the single-strain level, susceptibility to ACE varied among isolates, with changes in short-chain fatty acid levels. Although ACE significantly affected only three of the ten skin isolates, these strain-specific responses still led to measurable changes at the community level. Our findings highlight the potential of ACE to modulate the human skin microbiome and underscore the need to integrate single-strain and community-level approaches into pesticide hazard assessment to capture both mechanistic insights and more biologically relevant outcomes.