Ionophore coccidiostats: risk of CO-selectioN of antImicrobial resistance - Clinical impact and intervention strategies

Today’s intensive broiler production is highly dependent on in-feed ionophore coccidiostats. Because these ionophores are not used in humans, it is widely assumed their use does not impact human health. However, recent evidence suggests that ionophores drive the co-selection of vancomycin resistance in enterococci, and could also promote transmission of other medically relevant antimicrobial resistance (AMR) in gram-positive bacteria, potentially compromising human health. The aim of this project is to explore the consequences of ionophore use, and to assess the effect of alternatives to ionophores on the dissemination of clinically relevant AMR. The project will investigate ionophore resistance in enterococci and S. aureus from a One Health perspective, analyzing geographically diverse populations originating from poultry, retail meat, environment and human isolates. Whole genome sequencing will be used for comparative genomics, and the genetic and molecular origin of the encountered phenotypical ionophore resistance will be explored in detail. The results will contribute to a better understanding of the human health impact of ionophore use in poultry industry. In parallel, intervention strategies reducing the dependence of broiler production on ionophores will be evaluated for their effect on AMR transmission, providing leads for reducing the risk of AMR transmission within the animal reservoir, and ultimately, to humans. The results will provide crucial input for policy discussions on the sustainability of the prophylactic use of ionophores in broiler production.