Feed additive influences antibiotic resistance

Published on
June 9, 2022

Intensive broiler farming is highly dependent on the use of coccidiostats. These are feed additives that are given to these animals to prevent intestinal infections with certain parasites. The most important group of coccidiostats, the ionophores, have an antibacterial effect in addition to an antiparasitic effect. Since ionophores are not used in human infections, it has been assumed until now that their large-scale use in poultry has no consequences for human health care. Research by the WUR, however, shows that ionophores spread resistance to other antibiotics and may therefore have an influence.

Resistant bacteria

Researchers from Wageningen Food Safety Research (WUR) found bacteria resistant to ionophores in poultry meat samples. DNA research showed that the genes that cause resistance to ionophores are located on plasmids that also contain resistance to other antibiotics important to humans. Plasmids are small pieces of circular DNA that can be easily transferred between bacteria and play an important role in the spread of antibiotic resistance.

This discovery means that the use of ionophores could lead to the spread of resistance to other antibiotics important to humans.


To gain more insight into the magnitude of this problem, the JPIAMR project ICONIC was recently started.

This project looks at the spread of ionophores resistance in bacteria in several European countries from a One Health perspective. Vaccination is also being investigated as an alternative to prevent coccidiosis. The results of this study should provide more clarity about the scope of this problem, the consequences for humans and thus contribute to the answer to the question whether the large-scale preventive use of ionophores in poultry farming is still justified.