Ionophore resistance and potential risk of ionophore driven co-selection of clinically relevant antimicrobial resistance in poultry

Today’s intensive broiler production is highly dependent on ionophore coccidiostats. These antiparasitic agents are applied as feed additives. The most important group, the ionophores, not only exhibit antiparasitic activity but are also antimicrobial against Gram-positive bacteria. Because these ionophores are not used in humans, it is widely assumed their use does not impact human health. However, recent Swedish and Norwegian research shows that ionophores can cause the co-selection of vancomycin resistance in enterococci.