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

Antimicrobial resistance is one of the world's most serious threats. Insight in the development, dispersal and prevention of antimicrobial resistance is of great importance for both public and animal health, food safety and sustainability.

The project will explore whether ionophores, which are used in large quantities for poultry worldwide, can lead to the selection of antimicrobial resistance, and whether this has consequences for human health.

In Norway, broilers have for several years been produced without the prophylactic use of ionophore coccidiostats.  Worldwide, however, 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 perform experiments to verify the indications that ionophores promote selection of VRE. Additionally, 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.

Project leader

Wageningen Food Safety Research (WFSR) is the food safety institute within Wageningen Research, part of Wageningen University and Research (WUR), the Netherlands. 

Project manager (NVI)

Anne Margrete Urdahl

Project partners

  • Norwegian Veterinary Institute (NVI), Norway
  • University of Oslo (UiO), Norway
  • Ospedale San Raffaele (OSR IRCCS), Italy
  • French agency for food, environmental and occupational health safety (ANSES), France
  • National Veterinary Research Institute (PiWet), Poland

Read more at JPIAMR 

ICONIC web page

Research information

Project Number
Funded by the Research Council of Norway
Research Areas
Antibiotic resistance, Bioinformatics, Zoonoses