The usage of antimicrobials should be reduced further in order to ensure the health and well-being of farm animals, according to a new literature study.
The study was carried out by NGO The Pew Charitable Trusts, and published recently in the peer-reviewed scientific journal BMC Veterinary Research and contains references to over a 100 studies worldwide.
The researchers write that the “link between agricultural antibiotic use and antibiotic resistance has remained contested by some, with potentially disruptive effects on efforts to move towards the judicious or prudent use of these drugs.”
Systematically evaluating types of evidence
The authors wrote that the goal of the review therefore was to systematically evaluate the types of evidence available for each step in the causal pathway from antimicrobial use on farms to human public health risk.
The researchers zoomed in on 4 different factors:
1. Antimicrobial drug use on farms and feedlots. The researchers pointed out that the information available on drug use on farms and feedlots often differs from country to country;
2. Risk of resistance emergence as a result of antimicrobial exposure on farms and feedlots;
3. Risk of infection due to resistant bacteria that emerged on-farm;
4. Excess morbidity and mortality caused by antimicrobial resistance traits that emerged on farms.
Exact quantification remains challenging
In the abstract of their publication, the researchers pointed out that the pathogen, antimicrobial drug and treatment regimen, and general setting (e.g., feed type) can have significant impacts on how quickly resistance emerges or spreads, for how long resistance may persist after antimicrobial exposures cease, and what public health impacts may be associated with antimicrobial use on farms.
Therefore, they added, an exact quantification of the public health burden attributable to antimicrobial drug use in animal agriculture compared to other sources remains challenging.
A microscopic view of methicillin-resistant Staphylococcus aureus (MRSA). Photo: CDC/ Janice Haney Carr
Antimicrobial use on farms and feedlots
In their conclusion, however, they also stated: “Importantly, even if some data gaps remain to be filled, there is no doubt that antimicrobial use on farms or feedlots contributes to the problem of antimicrobial resistance.”
The team advised that, “Even though more research is needed to close existing data gaps, obtain a better understanding of how antimicrobial drugs are actually used on farms or feedlots, and quantify the risk associated with antimicrobial use in animal agriculture, these findings reinforce the need to act now and restrict antibiotic use in animal agriculture to those instances necessary to ensure the health and well-being of the animals.”
The article in BMC Veterinary Research was written by Karin Hoelzer, Nora Wong, Joe Thomas, Kathy Talkington, Elizabeth Jungman and Allan Coukell, the Pew Charitable Trusts.