Understanding Antimicrobial Resistance in Animal Agriculture: Findings from Epidemiology, Economics, and Social Science

Antimicrobials –including antibiotics – are used in humans and livestock to prevent or treat infection. However, overuse of antimicrobials can lead disease-causing microbes to mutate and become ‘superbugs’, immune to the drugs that treat them, also known as developing antimicrobial resistance (AMR). In some cases, these mutations can lead to multi-drug resistance (MDR). Both AMR, and to a greater extent MDR, can make treating disease difficult, prolonged, expensive, and in some cases impossible. In fact, The World Health Organization has identified AMR as one of the top 10 global threats. One aspect of AMR – that of antibiotic resistance (ABR)—is specific to bacteria, as opposed to fungi or other microbes. In the context of animal agriculture, when humans consume meat or dairy that is improperly processed or cooked or come into contact with livestock or livestock waste carrying the resistant bacteria, they too may acquire those bacteria, possibly leading to infection.

While the threat posed by AMR and ABR are clear, solutions are less so given the many stakeholders involved, the risks posed by eliminating antibiotics from animal agriculture, the nuance in types of antibiotics, the lack of public understanding about ABR (including which antibiotics are important for human use), and the inability to quantify how acutely ABR in livestock impacts human health. To illuminate this critical and complex issue, five speakers representing the Johns Hopkins Bloomberg School of Public Health, the University of Maryland Baltimore County, and Cornell University gathered at Cornell’s College of Veterinary Medicine on December 5th to present their research through a collaborative seminar titled Understanding Antimicrobial Resistance in Animal Agriculture: Findings from Epidemiology, Economics, and Social Science.

The first presentation, given by Dr. Gabriel Innes, a veterinarian and PhD candidate from the Johns Hopkins Bloomberg School of Health, focused on factors that impact the risk of consumer’s exposure to meat contaminated with MDR bacteria. Dr. Innes found that animals raised USDA Organic had a lower odds of carrying MDR bacteria than conventional (i.e. not raised Organic) meat. Furthermore, conventional meat had a lower odds of carrying MDR bacteria when processed in a facility that also processed Organic meat, as opposed to a wholly conventional meat processor.

In addition to the method of raising and processing meat, Dr. Innes’ research showed that meat type, processing location, and the distance traveled from the processor to a retail store also affected the odds of consuming MDR-contaminated meat. Dr. Innes found that after a certain distance of travel, all retail meats had a similar odds of having MDR bacteria contamination. However, after adjusting for other factors such as region processed and state sold, the relationship was inverse: the odds of contamination were lower the farther the meat traveled. One explanation may be that meat that has to travel farther could be frozen longer, which may kill less hardy bacteria populations.

Next, Dr. Guillaume Lhermie, an Adjunct Assistant Professor with Cornell’s College of Veterinary Medicine and Assistant Professor of Veterinary and Public Health Economics at the University of Toulouse’s College of Veterinary Medicine, discussed the economic and structural consequences of removing antibiotics from farming to produce meat and dairy products. According to Dr. Lhermie, although weighing the economic costs and benefits of antibiotic use (ABU) can be challenging, certain programs aimed at decreasing ABU are “economic no-brainers”. For example, implementing preconditioning interventions in feedlot systems produce low-risk calves that are less prone to infection. These cows require less antibiotics (lessening the risk of developing and spreading ABR) and can be sold at higher prices, creating societal benefit for all stakeholders. Despite this, Dr. Lhermie found that less than 10% of feedlots have adopted this intervention due to structural bottlenecks in the beef production system, which do not support risk management approaches. However, enacting policy changes could shift this dynamic and enable structural changes that support these types of interventions.

AMR panelists in atrium

Seminar panelists left to right: Jaime Barrett, University of Maryland Baltimore County; Dr. Amelia Greiner Safi, Cornell University Master of Public Health Program; Dr. David Lansing, University of Maryland Baltimore County; Dr. Guillaume Lhermie, Cornell University College of Veterinary Medicine; Dr. Gabriel Innes, Johns Hopkins Bloomberg School of Public Health.

While the first half of the seminar focused on epidemiology and economic considerations, the second half focused on perception; particularly how industry stakeholders, consumers, and others perceive ABR. Perceptions are important to consider since they can drive purchasing, prescribing, and AMU behaviors—the same behaviors targeted by many interventions to limit ABR. The first of these presentations, led by PhD student Jaime Barrett and Dr. David Lansing from the University of Maryland Baltimore County, focused on how the lack of clear regulations regarding ABU has resulted in contrasting perceptions across a diverse group of stakeholders. Since 1970, the FDA has seen the need to limit antibiotics in animal feed, but the extent of these limits has been left to interpretation. While regulations stipulate that antibiotics must be ‘medically-important’ and used ‘judiciously’, the scope of these labels is undefined. To better understand how stakeholders have interpreted this mandate, Ms. Barrett and Dr. Lansing are currently conducting interviews with farmers, consumers, veterinarians, and public health advocates to map out their interpretations and identify where stakeholders’ opinions align and diverge.

Dr. Amelia Greiner Safi, a social and behavioral scientist who is core faculty in Cornell’s Master of Public Health Program and research faculty in the Department of Communication, concluded the seminar. In preliminary findings from interviews, Dr. Greiner Safi (and the multi-disciplinary research team co-led by Dr. Renata Ivanek) noted that conventional dairy farmers felt their use of antibiotics was generally already judicious and imperative to the welfare of their animals. Further, many were frustrated by consumer misconceptions about conventional milk quality and production practices. Some veterinarians agreed that Organic milk is portrayed not only as healthier for humans, but healthier for dairy cows, even though Organic-raised cows may suffer more due to untreated medical conditions. Conversely, dairy farmers producing Organic milk felt that eliminating antibiotics from their cows forced the industry to improve management practices to reduce their reliance on antibiotics.

Preliminary findings from two national surveys of consumers revealed that consumers were concerned about antibiotic use in dairy but not well-informed on the issue. Further, the data show conflicting trends. For example, the majority consumers said they were willing to pay more for Organic milk since those cows never received antibiotics. However, a majority of consumers also accepted that cows treated with antibiotics could be sold as Organic (which is not allowed in the United States). While consumers felt threatened by antibiotic use in dairy, the reason for this fear was unclear and not necessarily tied to ABR.

As each presenter in the seminar noted, the threat of AMR and ABR are real, but as a complex issue affecting a diverse group of stakeholders, there is no silver bullet solution. What is clear is that to effect meaningful change, farmers need to be included in regulatory efforts, the nuance surrounding AMR and ABR must be understood, and public perceptions need to be further explored. Any resulting solutions must be socially acceptable, economically viable and rooted in a One Health perspective that recognizes the inextricable welfare of humans, animals, and the environment.

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