Antimicrobial resistance is a “complex, global issue to be addressed globally,” according to Dr. Sara Steinlage with Elanco in introducing an April 2 forum “Antibiotics in Animal Agriculture: What You Need to Know,” organized by the New York Academy of Sciences.
The forum was the culmination of a year-long process looking into the topic of AMR in animal agriculture, according to Dr. Gilles Bergeron, who heads the nutrition science section at NYAS. The effort, sponsored by Elanco, resulted in five new papers published in a special volume of the Annals of the New York Academy of Sciences.
During the forum, speakers presented summaries of the papers.
H. Morgan Scott with Texas A&M University discussed the criteria for importance and guidelines for reducing antibiotic use.
While not all antibiotics were created equal, he said defining criticality of use depends on the circumstances of time and place. The most critical are those that still work for particular conditions for which physicians or others need those antibiotics, Scott said.
There are multiple lists that aim to classify the criticality of antimicrobials, such as a list by the World Health Organization but also national and regional lists. Scott said each of these lists differs and “that’s OK.”
The U.S. list is 16 years old, Scott said, noting that it is found as an appendix to the Food & Drug Administration’s Guidance for Industry 152.
Speaking on the complexities in AMR between domesticated animals, humans and the environment, David Graham with Newcastle University in the U.K. explained that there are two types of AMR: intrinsic — the historic, background resistance found in nature that can be found in ice cores from 150,000 years ago — and acquired.
Graham explained that acquired resistance is due to recent human use of antibiotics that has accelerated evolution of the microbial population, either in the gut of the treated animal or in the wider environment if the sanitary conditions are below standard. He said exposures to other factors such as minerals and chemicals may accelerate AMR development — AMR is “driven by microbial genetics and ecology.”
In agriculture, Graham said fecal matter and sanitation are critical to controlling the spread of AMR genes, because the scale of manure generation is so much greater in livestock and fecal management in agriculture often uses lower technologies than used in municipal sewage treatment on the human side.
He also pointed out that AMR transmission depends on disease class and the direction of spread is not always clear. There have been examples of AMR developing in companion animals, spreading first to people and then subsequently to livestock, Graham said.
If wildlife pick up AMR genes, they can complicate the pathways for tracking and identifying AMR sources, Graham added.
According to Jason Gill of Texas A&M, in an effort to reduce the use of antibiotics in animal agriculture, a number of effective or commercially viable alternatives have been implemented or are under development.
Gill said these strategies include flock or herd management practices to limit disease introduction and spread — such as vaccination, sanitation and access control — as well as judicious use of antimicrobials. Other management practices that improve overall animal health such as lowering animal stress levels and improving nutrition also help limit disease spread and, hence, the need for antibiotic use.
A newer strategy, and one that Gill is actively researching, is the use of bacteriophages to control pathogenic bacteria without the need for traditional antibiotics.
Karin Hoelzer with the Pew Trusts summarized the forum with the following five points that she gleaned from the presentations and the papers.
- The One Health approach is needed for dealing with AMR.
- AMR challenges are shared across sectors, including defining and measuring antimicrobial use and resistance, quantifying and ranking transmission pathways and finding effective solutions and demonstrating success. In this area, data is fundamental.
- Antimicrobial stewardship goals are shared across sectors.
- Existing data are sufficient to take action on reducing AMR spread.
- There are effective models, approaches and solutions to AMR out there.
The full text of all papers in the special issue Antimicrobial Resistance from Food Animal Production may be downloaded here.