Us Policies And Activities
In 1999, the U.S. Food and Drug Administration followed proposed guidelines with a document entitled A Proposed Framework for Evaluating and Assuring Human Safety of the Microbial Effects of Antimicrobial New Animal Drugs Intended for Use in Food-Producing Animals . This document elucidates strategies for managing risks associated with the use of antibiotics drugs in food-producing animals. Strategies include categorization of antibioitics based on their importance in human medicine revision of the pre-approval safety assessments for new animal drug applications to assess microbial safety post-approval monitoring for resistance development collection of food animal antibiotic use data and establishment of regulatory thresholds. While the framework document mainly outlines some guidelines, it is likely that parts of all of the recommendations will be adapted and will be used to guide new product development. Additionally, there are legislative initiatives before the U.S. Congress to adapt strong regulations regarding what antibiotics cannot be used for non-therapeutic uses in animals.
One of the most recent U.S. activities was the development by federal agencies of the U.S. Public Health Plan to Combat Antimicrobial Resistance . This is a blueprint for actions that will reduce antimicrobial resistance that is heavily focused on human and public health, but also contains specific actions and initiatives for agriculture and veterinary medicine .
Recommendations On Ways To Reduce The Overall Level Of Antibiotic Resistance In Agricultural Settings
Furthermore, the indiscriminate use of antibiotics in animal farming should be avoided. Veterinary officers and pharmacists should adhere strictly to the policies governing prescriptions of antibiotics used in animal farming. They should equally ensure that the farmers adhere to the dosage, length, and administration of treatment and withdrawal periods of antibiotics prescribed for a purpose, as well as the causative agent of the disease be diagnosed and antibiotic susceptibility testing conducted against the disease causative agent prior to prescription and employment of the antibiotics . Moreover, routine surveillance and detailed analysis of antibiotic residues present in foods of animal origin should be conducted before being dispatched or delivered for human consumption. Owing to the variations in antibiotic consumption patterns and differences in animal production systems between countries , we therefore advise that based on the country, stringent control and/or regulations should be implemented by policy makers to enforce the legitimate purchase and employment of antibiotics in animal farming.
Extent Of Antibiotic Use
Calculations of global antibiotic use in crops are based almost exclusively from data obtained from the USA against fire blight caused by Erwinia amylovora on apple and pear . This literature suggests that the amount of antibiotics used for crops in the USA is relatively low, in comparison to the quantities used in livestock and aquaculture, with estimates ranging from 0.26% to 0.5% of total agricultural antibiotic consumption . This has led authors to conclude that curtailing antibiotics use on crops would not lead to a major reduction in world use . However, the lack of surveillance programs, in many countries, combined with the lack of application records, frustrates any attempts to estimate the real amounts of antibiotics being applied. Where in-depth studies have been undertaken results may be surprising. In Costa Rica it has been suggested that the amounts of tetracycline and gentamicin used in on crops may be 200700 times the quantities used in human medicine .
Sundin and Wang suggest that antibiotics are not more widely used because of the expense involved, but that does not appear to be the case as the bulk costs of tetracycline and streptomycin are available at $10 and $1 per kilo respectively, a similar price to copper oxychloride . However, it is interesting to note that within the data set there are no antibiotics recommended in the African countries.
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Financial Impacts Of L Intracellularis
The net return to the farrow-to-finish pig farm under baseline productivity assumptions in which pigs reach 135.87 kg during their 27 weeks of growth is $4.99 per pig or $115,090 annually. L. intracellularis decreases farm profits by reducing the average daily gain, decreasing the feed efficiency and increasing the mortality on average for the entire growing herd . Reducing average daily gain increases the amount of time that it takes for a pig to reach market weight. Due to space limitations in a farrow-to-finish operation, shipping schedules are typically followed in order to make room for the next group of pigs that are coming into the barn, so the market pigs shipped are lighter and less desirable for the processor. Reduced feed efficiency of the growing pigs means more feed is required, and thus higher costs per pound of weight gain. Increased mortality reduces the number of market hogs for sale, but also means that the fixed costs for the farm must now be spread across fewer pigs, thus increasing the total cost to raise each pig.
Table 6. Financial Impact of Lawsonia intracellularis per marketed hog on a farrow-to-finish swine farm with 1,000 sows.
How Germs Can Spread To People From The Food Supply
Animals, like people, carry germs in their gut, which can include antimicrobial-resistant germs. These germs can spread between animals and in their environments . When animals are slaughtered and processed for food, these germs can contaminate meat or other animal products.
Animal waste can also carry antimicrobial-resistant germs. Fruits, vegetables, and other produce can become contaminated through contact with soil or water containing untreated or un-composted waste from animals.
People can get infections from food in different ways:
- From handling or eating meat, seafood, milk, or eggs that are raw or undercooked and contaminated with resistant germs
- From handling or eating fruits and vegetables contaminated with resistant germs
- From contact with untreated or un-composted animal waste, either directly or when it gets into water and the environment
- From touching or caring for animals without proper handwashing
Additionally, antibiotics and antifungals are sometimes applied as pesticides to manage plants and crop disease. Learn more about antimicrobial resistance in the environment.
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Antibiotic Resistance In The Water Environment
Microorganisms do not live in isolation , but are found in milieu/medium known as their habitat , which offers them with the appropriate nutritional and growth requirements necessary for survival. Consequently, water represents one of the most important habitats for bacteria on the planet earth, and serves as a main natural route for the dissemination of microorganisms between different environmental compartments and/or aquatic ecosystems, humans, and other animals . According to Taylor et al. , the aquatic environment is considered as a fundamental setting for environmental release, transformation, mixing, and persistence of antibiotic residues, antibiotic-resistant bacteria, and antibiotic resistance genes. The water environment can be subdivided into marine and fresh water based on salinity, average temperature, depth, and nutrient content . More elaborately, the microbial aquatic environment includes surface and ground waters, drinking water, tap water, and wastewater. These waters have dynamic and distinct bacterial composition patterns influenced by temporal and spatial unevenness in physicochemical and biotic factors, including environmental stresses and nutrient composition . Nevertheless, some known waterborne bacteria include E. coli, Vibrio, Shigella, and Salmonella species . The aquatic environment has been reported to be the origin and reservoir of antibiotic-resistant bacteria and resistance genes .
Recreational waters and antibiotic resistance
Antibiotic Resistance In Livestock Farming
According to Woolhouse et al. , antibiotic resistance in livestock farming can be looked at from four different viewpoints, i.e., the animals and animal-derived products, farm workers, and farm environmental sites . All these constitute the several compartments and different niches in the farm described as an ecosystem . Undoubtedly, farm animals are a very important component in understanding the interplay between humans, animals, and the environment regarding bacteria, antibiotics, and antibiotic resistance gene movement . The digestive tract of animals, like humans , is colonized with diverse microorganisms, including commensals and resistant bacteria. Thus, it serves as the most important reservoir of microorganisms. Therefore, it can play a vital role in the dissemination and acquisition of resistant bacteria and their resistance genes .
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Antibiotic Resistance In Agriculture: Perspectives On Upcoming Strategies To Overcome Upsurge In Resistance
Antibiotics are used extensively in agriculture, livestock and in animal husbandry.
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In agriculture, these are used to increase crop productivity in animal husbandry and livestock to treat sick animals and as growth promoters in animal feed at controlled concentrations.
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Bacteria are able to modify their genes under stress conditions by different mechanisms, and the resistance genes are cycled among agricultural soils and other different ecosystems through nutrient cycling.
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A number of significant molecular strategies have been proposed to reduce the occurrence of antibiotic resistance in bacterial genomes .
Ongoing Transmission In Humans Of Resistant Strains Originating In Livestock
In general, there is still a marked gap in our knowledge regarding the successful transfer of resistant bacteria from animals to humans, or vice versa. However, it is clear that the species barrier has been breached multiple times in both directions, with human-adapted strains giving rise to animal-adapted lineages as well as vice versa . In the case of S. aureus, population genetic analyses have clearly shown the existence of host-specific clonal lineages, implying that its adaptive evolution has led to host restriction due to ecological differences among different hosts MRSA ST398 derived from animals appears to be a case of mechanism 1 ,1), and uncertainty still remains about its origin and its implications in public health. In contrast, CC97 appears to have contributed two distinct host-switching events from animals to humans, resulting in sustained onward transmission and representing a clear example of mechanism 2 .
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How Could The Use Of Antibiotics In Livestock Production Affect Human Health
There are two main concerns about the human health effects of antibiotic use in livestock production. The focus in early regulation of antibiotics in food animals concerned residues in food products. These residues may cause allergic reactions and digestive problems in humans. The FDA has therefore established minimum intervals between the last dosage of antibiotics and the time of slaughter to prevent such residues.
The other main concern with feeding antibiotics to livestock is promotion of the development of drug-resistant bacteria. Studies reported the existence of drug-resistant bacteria in food animals shortly after antibiotics began to be used in production in the 1950s. Drug-resistant bacteria in animals may yield adverse human health effects if people come in contact with drug-resistant bacteria via food, live farm animals, manure, or shed animal material such as feathers, or with infected producers, processing facility workers, or others who live or work on farms. Infected people can then transmit drug-resistant illnesses to others.
Global Positions On Antibiotic Use In Farm Animals
In 2017, the World Health Organization recommended reducing antibiotic use in animals used in the food industry. Due to the increasing risk of antibiotic resistant bacteria, the WHO strongly suggested restrictions on antibiotics being used for growth promotion and antibiotics used on healthy animals. Animals that require antibiotics should be treated with antibiotics that pose the smallest risk to human health.HSBC also produced a report in October 2018 warning that the use of antibiotics in meat production could have “devastating” consequences for humans. It noted that many dairy and meat producers in Asia and the Americas had an economic incentive to continue high usage of antibiotics, particularly in crowded or unsanitary living conditions.
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Overview Of The Model
This study develops a bioeconomic modeling framework that can be used to measure the financial impacts of antibiotics and vaccines for managing disease in livestock. Specifically, this is done by estimating and comparing the relative cost-effectiveness of 12 antibiotic and vaccine options for managing L. intracellularis on a typical Canadian farrow-to-finish swine farm. To do this, the production and profitability of a pig farm were calculated under 40 different farm scenarios . The first scenario is the baseline empirical model and reflects a typical Canadian farrow-to-finish swine farm under normal conditions. The next three are disease scenarios which were created to reflect the different severity levels associated with the occurrence of L. intracellularis. Twelve disease management strategies were then imposed on each of the three disease scenarios with four considered as preventative and the other eight as therapeutic. The net result was 40 scenarios: one baseline with no disease, three disease scenarios with no treatment, and 36 disease management scenarios . The cost of L. intracellularis can be estimated by comparing the profits with and without the disease and the cost-effective management options can be determined by comparing profitability across the treatments under a given disease scenario.
The Role Of Supermarkets
Supermarkets play a key role in the prevention of antibiotic use. Many markets add their own antibiotics during the supply chain process, making meat appear presentable for a longer period of time while it stands on the shelves. This must be prevented as well, and is not in the control of sustainable farmers. These changes must be achieved through a matter of law and public policy.
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Develop A Scientific Agenda To Recommend Appropriate Study Designs And Specific Aims Related To Antimicrobial Use In Food Animals
A coordinated plan is needed to identify missing scientific data and to specify research designs and methods to address these needs. Although rigorous studies have been conducted in some disciplines, there has been a lack of serious and harmonized interdisciplinary effort to expand on the corpus of knowledge, which should be used to inform public policy. To result in a useful and complete list of research priorities, the agenda must include contributions by experts in basic sciences , clinical sciences , public health , social sciences , economics , and public policy . Research goals put forth in the agenda should be reflective of methodological weaknesses identified in the existing literature. For example, definitions of antibiotic uses in food animals should be standardized and designed to reflect specific goals the terms should be recognized across disciplines and used to classify the potential effects of different types of antibiotic use on human health. Another potential focus could be whether to approach research on the development of resistance narrowly or broadly to develop public health recommendations.
Global Use Of Antibiotics For Livestock
Use of antibiotics for livestock greatly exceeds that of uses for humans: although data collection on antibiotic use in some regions is poorly documented, its estimated that global veterinary consumption of antibiotics in 2013 was around 131,000 tonnes. In relative terms, antibiotic use in livestock and humans is similar, averaging 118 mg/PCU and 133 mg/kg, respectively.7
However, since total livestock biomass greatly exceeds that of human biomass, total antibiotic use for humans is estimated to be much lower around 40,000 tonnes in 2013.8 This means antibiotic use in livestock is likely to account for approximately 7080 percent of total consumption.
But why do we use antibiotics in agriculture?
Like humans, animals are susceptible to bacterial infection antibiotics are therefore used to treat infected animals. However, their application now extends beyond this. For farmers, often with large populations of animals , it is a priority to make sure that their livestock are in optimum health. The mass use of antibiotics as a preventative measure has therefore become increasingly common.
In addition to their use for infection treatment or prevention, antibiotics are, in some countries added to animal feed in order to enhance animal productivity and meat yields. This revelation that the supplementation of animal feed with antibiotics led to increased growth was a largely spontaneous discovery in the 1950s.9
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Antibiotic Use In Livestock
Antimicrobials have been widely used in livestock since the 1950s . Food animal production has steadily increased over the years, requiring better disease management on farms. More than 75% of antimicrobials in Canada have been used sub-therapeutically in farm animals to prevent disease and for growth promotion . In Canada, growth hormones are only approved for use in beef cows . All antibiotics used in livestock must meet Health Canadas standards for human and animal safety . For example, maximum levels of antibiotics allowed to be left in food are set at levels much lower than what could pose a health concern . The Canadian Food Inspection Agency randomly tests the safety levels of food and if standards are not met then the food will be removed from the food supply . As well, most producers work with their veterinarian to determine when it is appropriate to use antimicrobials and determine withdrawal periods so that treated animals or animal products do not enter the food supply until safe to do so .
There are 4 categories of antimicrobials 10:
And make sure to take a look at our
in the livestock industry!
References
Guidelines And Recommendations On The Use Of Antibiotics In Food Animals
Given the importance of antibiotic resistance as a public health problem, many governments and professional societies have reviewed existing scientific evidence and developed recommendations to limit all types of antibiotic use, including use in food animals. Depending on the nature and jurisdiction of each group, the findings may provide best practice guidelines for antibiotic use, prioritized agendas for research on the emergence of antibiotic resistance, recommendations for legislative action to regulate drug approval and surveillance processes, or enforceable laws on the manufacture, distribution, and prescription of antibiotics. Figure 5 summarizes recommendations directly related to use of antibiotics in food animal production for a sample of national and international guidance and policy documents.
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