Generated Summary
This paper, published by the independent Review on Antimicrobial Resistance (AMR), considers the impact of antibiotic use in animals, particularly the agricultural sector, as well as the release of antimicrobials and resistant bacteria into the environment from animal use, human use, and manufacturing plants. The paper sets out how the world could take action to substantially reduce the use of antibiotics in agriculture and the quantities being dispersed into the environment. The Review analyzed published, peer-reviewed research articles that address the issue of antibiotic use in agriculture. The outcomes of this literature review support the proposal that antibiotic use in animals is a factor in promoting resistance in humans. The paper proposes three broad interventions to take bold global action: 1. A global target to reduce antibiotic use in food production to an agreed level per kilogram of livestock and fish, along with restrictions on the use of antibiotics important for humans. 2. The rapid development of minimum standards to reduce antimicrobial manufacturing waste released into the environment. 3. Improved surveillance to monitor these problems, and progress against global targets. The paper focuses primarily on the roles that fiscal measures (that is, taxation and subsidies) and regulation could play in reducing the risks associated with agricultural use of antimicrobials and environmental contamination.
Key Findings & Statistics
- More than 70 percent of the antibiotics deemed medically important for human health by the FDA are used in livestock.
- Global consumption of antibiotics in agriculture is projected to increase by 67 percent from 2010 to 2030, and consumption of antibiotics amongst the BRICS will increase by 99 percent in that same time period.
- In the US, more than 70 percent of medically important antibiotics are used in animals.
- In the US, more than 70 percent of the antibiotics deemed medically important for human health by the FDA sold in the United States (and over 50 percent in most countries in the world) are used in livestock.
- The review found that of 139 academic studies, only seven (five percent) argued that there was not a link between antibiotic consumption in animals and resistance in humans, while 100 (72 percent) found evidence of a link.
- Animals in the USA consume more than twice as many medically important antibiotics as humans: 70% are consumed by animals, and 30% are consumed by humans.
- Use of antimicrobials in aquaculture in Norway fell by 99 percent between 1987 and 2013, despite the industry’s output growing more than 20 fold over that time.
- Estimates of total annual global antibiotic consumption in agriculture vary considerably, ranging from around 63,000 tonnes to over 240,000 tonnes.
- The proportion of antibiotics used in livestock compared with humans is also very surprising to many not well versed in this issue.
- In China, colistin-resistant E. coli was found in more than 20 percent of animals and in 15 percent of raw meat samples.
- The Netherlands reduced its antibiotic consumption by 56 percent in three years.
- Of the 280 papers the review looked at, 88 (31 percent) were deemed not to be applicable. Of the remaining 192 papers, 114 (59 percent) openly stated or contained evidence to suggest that antibiotic use in agriculture increases the number of resistant infections in humans. Only 15 (eight percent) argued that there was no link between antibiotic use and resistance. The other 63 did not take a clear stance.
- Of the 139 academic studies the Review found, only seven (five percent) argued that there was no link between antibiotic consumption in animals and resistance in humans, while 100 (72 percent) found evidence of a link.
- Of the 41 antibiotics that are approved for use in food producing animals by the FDA, 31 are categorised as being medically important for human use.
- Denmark: Between 1992 and 2008, Danish swine production increased by 47 percent. During the same period, antimicrobial use in swine decreased by 51 percent. Between 1995 and 2008, antimicrobial use in poultry decreased 90 percent in absolute terms.
Other Important Findings
- The risks associated with the high use of antimicrobials are threefold: 1. Presents the risk that drug-resistant strains are passed on through direct contact between humans and animals (notably farmers). 2. These drug-resistant strains have the potential to be passed onto humans more generally through the food chain. 3. There is a further indirect threat to human health as result of animal excretion.
- Much of the use of antibiotics in animals is not therapeutic; significant volumes are used either prophylactically amongst healthy animals, to stop the development of an infection within a flock or herd, or simply for growth promotion, to speed up the pace at which animals gain weight.
- Just as there is a clear correlation between rising levels of human use of antibiotics and growing resistance, the same is essentially true in agriculture.
- Some last-resort antibiotics for humans are being used extensively in animals, with no replacements as of yet on the way.
- This gene is particularly worrying as it can transfer easily from bacteria to bacteria, meaning it could spread quickly.
- The risk of drug resistance must urgently become a key environmental consideration for all pharmaceutical companies, healthcare buyers and regulatory agencies everywhere.
- During the manufacture of antimicrobials, destined for human or veterinary use, untreated waste products containing high levels of end products or active ingredients may be discharged into water courses.
- Use of antibiotics in aquaculture and its impact on the environment is a growing concern amongst scientists, yet quantifying the amount of use and how much is being disseminated into the environment is very difficult.
- Fungal infections contribute to the deaths of almost three quarters of a million people each year.
- Greater research is needed to understand why Europe uses a comparatively large amount of fungicides, and to see if lessons can be learnt from use in the US.
- In agriculture, these should take into account the key drivers of the real or perceived need for antibiotics, whether for use as therapy, prophylaxis (prevention), or growth promotion.
- There remain too many knowledge gaps regarding patterns of antimicrobial use in agriculture and release during manufacturing, and what this means for resistance and, ultimately, human health.
- We found 280 papers, via the National Center for Biotechnology Information’s (NCBI) PubMed database with the search terms “drug resistance, microbial” AND “agriculture”.
- The link between the use of antibiotics in animals and resistant infections in humans, however, is more contentious and normally focuses on the likelihood that resistant bacteria in animals, created by the selection pressures of antibiotic use, will be transferred to humans.
- In 2006 the EU banned all antibiotics used as growth promoters and required veterinary prescriptions for antibiotics used in food animals.
- As with the human health aspects of AMR, these are complex issues that require concerted, coordinated action at an international level.
- The World Health Organization (WHO) released its Global Action Plan for AMR, with one of its main objectives being to “optimize the use of antimicrobial medicines in human and animal health”.
- The most plausible explanation for the wide occurrence of this newly discovered resistance gene in animals and meat is that bacteria with it have been selected by farmers giving colistin to their animals.
Limitations Noted in the Document
- The precise quantity of antimicrobials used in food production globally is difficult to estimate, but the evidence suggests that it is at least as great as the amount used by humans.
- The paper notes that estimates of the total annual global antibiotic consumption in agriculture vary considerably, due to poor surveillance and data collection in many countries.
- Use of antibiotics in aquaculture and its impact on the environment is a growing concern amongst scientists, yet quantifying the amount of use and how much is being disseminated into the environment is very difficult.
- The paper does not prescribe how countries should act.
- In light of this information, we believe that there is sufficient evidence showing that the world needs to start curtailing the quantities of antimicrobials used in agriculture now. Where gaps in the evidence remain, they should be filled.
- The number of patients relying on antifungals to stay alive has increased over the last two decades, as advances in modern medicine have allowed many more patients with weakened immune systems to survive.
- The analysis showed no reduction in productivity for countries that used smaller quantities of antibiotics.
- While these proposals may appear radical, The Netherlands reduced its consumption by 56 percent in three years, so that it is now only slightly above a threshold of 50mg of antibiotics/kg, without bearing large economic costs.
Conclusion
The primary goal is to reduce unnecessary use of antimicrobials in agriculture. There is growing evidence to suggest that antibiotic use in animals is a factor in promoting resistance in humans. Reducing the quantity of use, and the types of antibiotics used are also important. Countries need to agree to restrict, or even ban, the use of antibiotics in animals that are important for humans. The rapid development of minimum standards to reduce antimicrobial manufacturing waste released into the environment is also critical, as the risk of drug resistance must urgently become a key environmental consideration. There remain too many knowledge gaps regarding patterns of antimicrobial use in agriculture and release during manufacturing, and what this means for resistance and, ultimately, human health. The economic case for interventions to lower unnecessary use exists, but policy interventions should be tailored to each individual country to meet their targets. The paper highlights that it is possible to significantly increase use, without a damaging economic impact, and the counter argument to this is the increased financial cost that could be placed on food producers through restricting use, which could ultimately mean higher meat prices for consumers. The world has been successful at coming together to tackle similar environmental and public good challenges to the ones this paper highlights, which we believe we can learn lessons from. The approach needs to be dynamic enough for any new antibiotics for human use to be added, and potentially allow for antibiotics to be removed if they are deemed no longer to be important for human health. We must radically improve the surveillance of antibiotic use in agriculture and antimicrobial manufacturing waste. The proposals require governments, experts, and international bodies to set an ambitious but achievable target for countries to reach. We need to take urgent steps to make sure that the use of antibiotics in animals that are important for human use, are restricted and where necessary banned.