Effects of Livestock Antimicrobial Resistance on Residues in Animal Products and Public Episteme
Christian Xu
The Division of Science, The City College of New York
ENGL 21003: Writing for the Sciences
Professor Brittany Zayas
May 20, 2023
Word Count: 2944
Table of Contents
Introduction………………………………………………………………………………………3
History of Farmed Livestock, Antimicrobial Use, and Animal Food Production……………4
Antimicrobial Resistance in Farmed Livestock and Residues in Animal Products…………6
Public Episteme Regarding AMR Residues in Animal Products……………………………..8
Solutions/Limitations…………………………………………………………………………….9
Conclusion……………………………………………………………………………………….11
Introduction
The consumption of animal products is a vital nutritional component in numerous cultural diets of people across the globe. In the United States alone, approximately 10 billion farmland animals are bred and raised annually for consumer consumption (Parr, 2018). The primarily consumed animal products by humans include meats, milk, and eggs derived from farmland livestocks. This isn’t particularly surprising since meats from livestocks are especially calorically dense compared to their leafy-green counterparts: vegetables. The popularity of meat and its subsequent consumption has evidently increased exponentially over the past decades. As Deckers (2016) points out, a statistic from the Food and Agricultural Organization of the United Nations (FAO) in 2014 demonstrated that the total animal tonnages by weight from 1961 to 2006 has increased from 71,357,169 tonnes to 262,919,740 tonnes respectively. By 2012, this statistic had risen to 302,390,507 tonnes. As a result, this illustrates an over fourfold increase in total weight of farmland animals since the 1960s. The exponential growth of livestock weight throughout the decade also goes hand-in-hand with the widespread usage of antibiotics in the farmed animal industry. For instance, of the total antibiotics sold in the United States, 70%-80% are used for animal agriculture and food production, not just humans (Aguirre, 2017). To add on, Aguirre (2017) also states, consumption of antibiotics in the farmed animal sector for food production is expected to rise to 67% by 2030 globally. Countries such China, India, and Brazil have high economic demands for meat products due to their elevated populations. Therefore, these nations are expected to have an antibiotic consumption rate increase of 100% by 2030 alone (Aguirre, 2017). The excessive use of antibiotics not just simply for therapeutic treatment of livestock infections, but also for preventative measures and as a growth factor in animal size, leads to a greater risk for the development of antimicrobial resistance (AMR) in farmed livestock populations. Consequently, the consumption of animal products with AMR could lead to the transmission of these residues to humans. These residues have many different methods of transmittance, such as through the contact or consumption of contaminated water from animal waste, or simply living in close proximity to areas with dense livestock populations (Parr, 2018). As such, the overuse of antimicrobials, specifically antibiotics in farm animals, fosters a substantial risk in individual’s health as a result of residue deposits from animal products. Finally, public epistemology regarding AMR in livestocks, and the presence of these residues in animal food products, promotes varying levels of purchasing behaviors or opinions on which animal products consumers view is best for their health.
History of Farmed Livestock, Antimicrobial Use, and Animal Food Production
The importance of antibiotics in the modern healthcare system cannot be overlooked. Their extensive use constitutes the key to treating and even curing many of humankind’s bacteria-borne diseases, from the extremely rare to the most common. The broader term for antibiotics places these drugs under the umbrella class of antimicrobials. Antimicrobials are a widespread class of drugs that target and treat varying disease-causing microorganisms, not just bacteria, some of which include, antifungals, antiparasitics, and antivirals. The history of the first class of antimicrobials plays a pivotal role in the early development of farmed livestock and the ensuing production of animal based products. The subsequent discovery of these vital first generation drugs display a pronounced impact on livestock health and production at the time, so much so that the extended uses of antibiotics in the livestock industry can be seen to this day. The discovery of one of the earliest antimicrobial drugs, Prontosil, derived from the synthesis of sulfonamides, a class of antimicrobials, dates back to the early 1930s (Kirchhelle, 2020). The subsequent discoveries sparked extensive research from industrial pharmaceutical companies and laboratories to mass screen in search of compounds with antimicrobial properties. As a result, this set into motion the second generation of antimicrobial research. Not long after, the isolation of antibacterial properties from the fungus, Penicillium notatum, yielded the first infamous antibiotic, penicillin. Following the crucial invention of the first antibacterial drug, the resulting event led to the mass production of sulfonamides and penicillin, drastically decreasing the price of antimicrobials and dramatically increasing pharmaceutical competition. Thus, drug companies looked to alternative markets to sell their antibiotics and other related antimicrobial products to maximize profits. These alternative outlets included the farmed animal and veterinary sectors. However, during the same decade in which sulfonamides were discovered, they were already initiated by farmers to be used on livestock. As early as the late 1930s, sulfonamides and antibiotics such as gramicidin were used to treat cows with bacterial udder infections and poultry with gastro-enteric infection (Kirchhelle, 2020). Despite the early implementation of antimicrobial drugs in the animal sector, the utilization of antimicrobials in farms to bolster improvements in livestock health was not the first instance of medical supplementation. Medicated feeds used in conjunction with metabolism-enhancing supplements were already implemented throughout the livestock population. However, the positive feedback that these first waves of antimicrobial yielded cannot be dismissed. Piglet mortality rates on Pfizer farms declined to 5% from between 21% and 33% (Kirchhelle, 2020). In the modern scope, antibiotic use in the livestock industry has only continued to increase. A report by the United States FDA in 2015 found that 15.58 million kilograms of antibiotics were approved and authorized for use in farmed animals for food production (Parr, 2018). Moreover, the domestic selling of medically significant antibiotics has increased by 2% from 2014-2015 and a 26% marked increase from 2009-2015 (Parr, 2018). These results portray the everlasting importance that antibiotics play in the animal and meat production industry.
Antimicrobial Resistance in Farmed Livestock and Residues in Animal Products
It comes as no surprise that the advent of antimicrobials has led to a substantial increase in the overall health of livestocks and the productivity of farm animals that are raised for the purpose of food production. However, the ubiquitous use of antimicrobials not just for treating infectious diseases within the livestock population, but also as preventative measures against future infections, could present a rise in AMR pathogens within the animal populace. The misuse of antibiotics, or more specifically its overuse, plays a significant role as the catalyst for the proliferation of animal AMR diseases in the farmland setting. The earliest period in time which noted the existence and relevance of AMR and antibiotic-resistant pathogens, once again took place during the exact decade when sulfonamides were discovered and utilized by animal farmers. In fact, not long after their discovery, in the late 1930s, researchers had noticed the growth of bacterial resistance to sulfonamides. Subsequently, the recognition of sulfonamide-resistance and the presence of microbes with these unique genes was what also spurred the research behind antimicrobial properties derived from certain microorganisms. As such the first clinical trial of penicillin took place in 1939. However, similar to sulfonamide-resistance, only one year after the clinical trial of penicillin in 1940, researchers at Oxford were made aware of the discovery of penicillin-resistant staphylococci. In recent years farmed animal products have been found to contain strains of Salmonella, E. coli, and Campylobacter that are antibiotic resistant (Deckers, 2016). Human consumption of animal flesh and meats contaminated with AMR E. Coli and Salmonella has led to outbreaks within communities. People within these communities purchase and consume the same distributed meat products containing these AMR food-borne bacteria, causing food-related illnesses and even death. Other strains of the aforementioned zoonotic pathogens, microorganisms that can be transmitted from vertebrate animals to humans, are especially threatening as they are resistant to a broad range of antibiotics. One such zoonotic pathogen that has shown existence in both animals and humans through transmission is Enterococcus. The use of the antibiotics on chicken farms, specifically avoparcin, has fostered the development of vancomycin-resistant Enterococcus, leading to its presence within the bowels of humans (Deckers, 2016). To further demonstrate the immense efficiency and potency of AMR genes, the same vancomycin-resistant genes found in AMR Enterococcus have been discovered to have spread to the more renowned AMR pathogen, methicillin-resistant Staphylococcus aureus (MRSA). The spreading and transferring of genes, more precisely known as horizontal AMR gene transferring, from the bacteria named previously, was made aware in 1966 by the New England Journal of Medicine. This is particularly alarming as prior to this discovery, MRSA was only thought to be nosocomial (hospital-acquired) (Deckers, 2016). However, the pre-existenting and prevailing use of antibiotics on farmed livestock, coupled with the transferring of genes across different bacteria, has led to events of community-acquired MRSA (CA-MRSA). This transmission of MRSA from animals to humans within the community has been evident in Dutch livestock farmers and slaughterhouse workers. One such instance details the findings of a Dutch which indicated that 27% of pig farmers were carriers of MRSA, whereas only 0.19% were carriers with no prior contact with farmed animals. Consequently, through the genetic transferring of AMR genes between similar microorganisms, antibiotic overuse acts as the medium for AMR transmission among livestock and humans. The subsequent zoonotic transmissions ultimately results in AMR contaminants, or more precisely animal residues, depositing in animal food products, which humans then consume.
Public Episteme Regarding AMR Residues in Animal Products
Public perceptions regarding the presence of AMR residues in animal products from the use of antibiotics on livestocks, raised concern over the food safety of consuming these products. This concern has been a deep-seated issue dating as far back as the 1900s. The public’s skepticism to the foods they consumed was in part due to the muckraking and exposing of the poor sanitation conditions of the food industry from Upton Sinclair publication of The Jungle (1906). In the early 1950s, in response to the increasing wariness over cancer rates, committees in charge of analyzing the use of chemicals in food production began to raise awareness over the lack of adequate testing for carcinogens. This same concern was echoed in response to the heightened instances of antibiotic allergies, especially towards penicillin between 1953 and early 1957. These concerns were as a result of an FDA survey in 1957 which found that 10% of U.S milk was contaminated with penicillin. These early findings likely left a mark on the minds of U.S consumers regarding the health implications of these invisible contaminants. In a study of 170 participants conducted by Smith et al. (2016) researchers analyzed the psychological behaviors of persuasiveness among those who were consumers of antibiotic-free meats. The objective of the study was to determine how prior knowledge and experiences with antibiotic-resistance, whether in livestocks or humans, affected their decision to purchase antibiotic-free meats. Furthermore, they determined if these variables would influence the likelihood of those who consume antibiotic-free meats of spreading the perceived benefits to others within their social circle. The study revealed that participants on average possessed negative emotions towards antibiotic use in animals, with data illustrating that 55% of participants had made attempts to buy antibiotic-free meat products. Further breakdown of the result placed the participants into three classes: Purchaser, Resisters, New Adopters. Results indicate that 52% of the participant pool were identified as Purchaser, 28% as Resisters, and 21% as New Adopters. As Smith et al. (2016) details, Purchasers possess a high likelihood of negative attitudes towards antibiotic use. In addition, they had both previous and future intentions of buying antibiotic-free meat. Finally, they also demonstrate positive norms, or encouragement from others, to purchase antibiotic-free meat. Resisters possess a low likelihood of all aspects. New adopters also demonstrated a high likelihood of negative attitudes towards antibiotic use, persuading others to buy antibiotic-free meats, and attempting to buy antibiotic-free meats in the future. However, they were unlikely to experience positive norms or attempt to purchase antibiotic-free meats previously.
Solutions/Limitations
One plausible solution to minimizing the ever increasing dependency on antibiotics in the livestock industry, as well as limiting antimicrobial resistance residue in animal products, is the development of laboratory grown meat. Laboratory grown meat utilizes a small sample of stem cells taken from the live muscle of animals. Once obtained, scientists layer the muscle stem cells onto a flexible and porous three-dimensional “scaffold”. A nutrient-rich serum soaks and infuses the cells through the porous material, promoting rapid cell reproduction. The benefits of meats created in laboratories is the decreased contact that the synthesized meats would have with the outside environment and their contaminants, in this case pathogens. Therefore, the synthetic meats grown will occupy a sterile environment where scientists can work to develop the product without the need for antibiotics. In addition, the risk of food-borne illnesses microbes and their antibiotic-resistant counterparts from the overuse of antibiotics is reduced as a result of the limited use of them. Thus, antimicrobial resistant residue in laboratory grown meat is greatly reduced (Mayhall, 2019). However, the drawbacks of producing meat in a lab are extensive. Firstly, the laboratory equipment required to create synthetic meat is the bulk of the expense, the start-up cost. This doesn’t take into account the cost of operating the machinery and using resources to create the actual product. Vital technology such as bio-reactors, vats that aid in the cellular growth of muscle cells, are mandatory, likely requiring multiple units also (Mayhall, 2019). More worryingly, the major drawback concern is the ethicality behind the means of acquiring the nutrient-rich serum needed to simulate cellular growth. As Mayhall (2019) points out, “Another big drawback is the use of fetal bovine serum. For an industry that prides itself on having a positive effect for animal welfare, it is obviously hypocritical to extract blood from cow fetuses in slaughterhouses, remove the red blood cells, and use the leftover material as a main ingredient in the stem cell nutrient serum” (Mayhall, 2019). When analyzing solutions it is vital to pinpoint whether the proposed alternative ultimately achieves the main objectives. In this scenario, the main objective of laboratory grown meat is to limit the physiological stress endured by animals on farms. The limitations of stressors include the elimination of antibiotics and the crowding of livestocks which induces rampant infection within the population. An argument could be made against laboratory grown meats in that the process of extracting blood cells from cow fetuses is not much of an improvement in terms of animal well-being than simply slaughtering cows for their meat instead. Both products’ start and endpoints are derived from the use of animal meat.
Conclusion
The history of antibiotic use farmed animals and the first antimicrobial drugs are thus eternally intertwined. The overuse of antibiotics in both the farmed animal sector and the healthcare sector has always been an enduring issue. Currently, an estimated 80% of all antibiotics distributed and sold in the United States are used in feeds for farmed animals (Parr, 2018). Globally, of all antibiotics produced an estimated half are given to farmed animals (Deckers, 2016). The sheer quantity of antibiotics flooding the farmed animal sector promotes the development of AMR in livestock populations. Eventually these AMR found in animals will transmit to humans in the form of residues through the consumption of animal products. In the United States alone, antibiotic-resistance accounts for two million infections and 23,000 deaths (Aguirre, 2017). As Aguirre (2017) explains, on the global scale, around 700,000 deaths are attributed to antibiotic-resistant infections, with these current trends, 300 million deaths could result over the next 35 years. Public knowledge of antibiotic use in animal husbandry and the risk of AMR has brought awareness to these dangers, resulting in the social persuasiveness of purchasing antibiotic-free animal products. Finally, one of the solutions proposed in reducing livestock AMR and their associated residues is the reliance on laboratory grown meats. Although synthetic meats reduce, if not eliminate, the chances of AMR development in animal populations, their hypocritical and ethical methods of creating the product is called into question.
References
Aguirre, E. (2017). An International Model for Antibiotics Regulation. Food and Drug Law Journal, 72(2), 295–313. https://www.jstor.org/stable/26661137
Deckers, J 2016 Animal (De)liberation: Should the Consumption of Animal Products Be Banned? Pp. 13–50. London: Ubiquity Press. DOI: http://dx.doi.org/10.5334/bay.b. License: CC-BY 4.0
KIRCHHELLE, C. (2020). Marketplace Environmentalism: Antibiotics, Public Concerns, and Consumer Solutions. In Pyrrhic Progress: The History of Antibiotics in Anglo-American Food Production (pp. 143–162). Rutgers University Press. https://doi.org/10.2307/j.ctvscxrvf.11
KIRCHHELLE, C. (2020). Picking One’s Poisons: Antibiotics and the Public. In Pyrrhic Progress: The History of Antibiotics in Anglo-American Food Production (pp. 17–32). Rutgers University Press. https://doi.org/10.2307/j.ctvscxrvf.5
Mayhall, T. A. (2019). The Meat of the Matter: Regulating a Laboratory-Grown Alternative. Food and Drug Law Journal, 74(1), 151–169. https://www.jstor.org/stable/26826975
Parr, A. (2018). Agribusiness and Antibiotics: A Market-Based Solution. Food and Drug Law Journal, 73(2), 338–360. https://www.jstor.org/stable/26661180
Smith, R. A., Zhu, X., Shartle, K., Glick, L., & M’ikanatha, N. M. (2016). Understanding the public’s intentions to purchase and to persuade others to purchase antibiotic-free meat. Health Communication, 32(8), 945–953. https://doi.org/10.1080/10410236.2016.1196415
