A global approach to human and animal health
With a holistically integrated approach based on farm, feed and health management, antibiotic use can be reduced significantly on a global scale – with equal or even improved productivity.”
Knut Nesse, CEO of Nutreco at the UN High-level Meeting on Antimicrobial Resistance (New York)
Just as microbes know no borders, there are no borders between human and animal health. This led to the collaboration between the United Nations Food and Agriculture Organization, The World Organisation for Animal Health and World Health Organization, which produced a Tripartite Concept Note addressing health risks at the animal-human-ecosystems interfaces. (http://www.who.int/influenza/resources/documents/tripartite_concept_note_hanoi_042011_en.pdf)
Bacteria are constantly being exchanged between animals and humans. Animals may carry infectious agents and can contract many infections which are similar or identical to those affecting humans. In some settings, intensive livestock production, fish and seafood farming, and the medical care of household pets rely on the same types of antibiotics as those used to treat people. Antibiotics are often used to treat sick animals, but sometimes also as a preventive measure to protect healthy animals when they are in contact with sick ones or during periods when animals are travelling or exposed to other stress factors. Rushton et al. The Use of Antimicrobials in the Livestock Sector. OECD Food, Agriculture and Fisheries Papers. DOI:10.1787/18156797 Antibiotics are also sometimes used as growth promoters for livestock, even in the absence of disease: the benefit of this practice is controversial and it has been partially or totally banned in a number of countries, including Mexico, Brazil, Australia, New Zealand, Vietnam and the European Union. The World Health Organization recommends that farmers and the food industry stop using antibiotics routinely to promote growth and prevent disease in healthy animals WHO Press release Nov. 2017 - http://www.who.int/mediacentre/news/releases/2017/antibiotics-animals-effectiveness/en/.
The Food and Agriculture Organization estimates that, every year, 62 billion animals are used for the production of meat, milk and eggs, a figure which is likely to double by 2050. In many countries, the number of chicken and cattle far exceeds that of the human population. Globally, the total biomass of livestock is two and a half times that of the human population. FAO online database.
(http://faostat3.fao.org/home/E) It is therefore not surprising that the majority of antibiotics sold worldwide are used by the meat, dairy and aquaculture industries. Moreover, increasing worldwide demand for meat has led to antibiotic consumption in animals rising by 70% over the past decade. Van Boeckel TP et al. Global trends in antimicrobial use in food animals. PNAS Published online before print March 19, 2015. DOI:10.1073/pnas.1503141112 Estimates for some countries point to as much as 80% of antibiotics being consumed by livestock. FDA Annual Summary Report on Antimicrobials Sold or Distributed in 2012 for Use in Food-Producing Animals. Food and Drug Administration, Department of Health and Human Services. 2014
“One Stop Shop” web portal
The U.S. Department of Agriculture has launched a “One Stop Shop” web portal for One Health information. The site aims to contribute to training and educating animal health professionals on several issues related to antibiotic resistance and focuses on 3 main areas: antimicrobial resistance, avian influenza, influenza in swine.
Some restaurants and fast-food chains now advertise antibiotic-free meat in their menu. Raising antibiotic-free animals may be more expensive in some regions or countries, but many consumers are willing to pay more to avoid the risk of eating food containing antibiotics or antibiotic-resistant bacteria.
Assessing the burden of disease caused by antibiotic resistant bacteria in the veterinary sector and its impact on humans at the global level is complex. However, in countries where data is available, use of antibiotics in livestock tends to correlate with antibiotic resistance in pathogens affecting humans. In its 2011 report Tackling antibiotic resistance from a food safety perspective in Europe, the World Health Organization stated that “resistance in the food-borne bacteria Salmonella belong to the Salmonella genus of Enterobacteriaceae. They cause two types of illness: food-borne gastroenteritis (salmonellosis), and typhoid/paratyphoid fevers. and Campylobacter is clearly linked to antibiotic use in food animals, and food-borne diseases caused by such resistant bacteria are well documented in people.”
European Centre for Disease Prevention and Control/EFSA/EMA joint reports unveiled a wide array of correlations between consumption of antimicrobial agents by humans and food-producing animals and occurrence of antimicrobial resistance in bacteria. ECDC (European Centre for Disease Prevention and Control), EFSA (European Food Safety Authority) and EMA (European Medicines Agency), 2015. ECDC/EFSA/EMA first joint report on the integrated analysis of the consumption of antimicrobial agents and occurrence of antimicrobial resistance in bacteria from humans and food-producing animals. EFSA Journal 2015;13(1):4006, 114 pp. DOI:10.2903/j.efsa.2015.4006 (https://www.efsa.europa.eu/en/efsajournal/pub/4872) Furthermore, extensive monitoring in slaughterhouses and retail outlets in 28 EU countries in 2016 revealed very high levels of multidrug resistance in some strains of Salmonella belong to the Salmonella genus of Enterobacteriaceae. They cause two types of illness: food-borne gastroenteritis (salmonellosis), and typhoid/paratyphoid fevers.. The European Union summary report on antimicrobial resistance in zoonotic and indicator bacteria from humans, animals and food in 2016. doi: 10.2903/j.efsa.2018.5182
To assist countries in applying a One Health approach, the World Health Organization Advisory Group on Integrated Surveillance of Antimicrobial Resistance developed a new guidance document. (http://apps.who.int/iris/bitstream/10665/255747/1/9789241512411-eng.pdf?ua=1) To steer evidence-based policies, this guidance recommends to monitor:
- Prevalence of AMR in different reservoirs;
- AMR trends over time;
- Association between AMR and the use of antimicrobial agents.
Interventions that restrict antibiotic use in food-producing animals have often been associated with a reduction in the presence of antibiotic-resistant bacteria in these animals. Lancet Planet Health 2017; 1: e316–27
Bacteria and the environment
All environmental compartments are connected. Humans and animals constantly exchange pathogenic or non-pathogenic bacteria, with or without resistance to antibiotics. These bacteria can easily spread into the environment though different routes.
The spread of antibiotic resistance
Humans, pets, livestock and fish farms rely on similar classes of antibiotics to fight infectious diseases. Both pathogenic and non-pathogenic bacteria evolve or exchange the ability to survive when exposed to these antibiotics. Then, they can spread into the environment through different routes, e.g. through water sanitation systems Antimicrobial resistance WHO Fact sheet N°194, updated April 2015.
(http://www.who.int/mediacentre/factsheets/fs194/en), as wastewater treatment facilities do not entirely remove antibiotic resistant bacteria before releasing water into waterways. Another common route is through the application of animal manure containing resistant bacteria to fields with cultivated crops CDC website about antimicrobial resistance.
(http://www.cdc.gov/drugresistance), where such bacteria can flourish on plants Laxminarayan et al. Antibiotic resistance - the need for global solutions. Lancet Infect Dis 2013;13:1057-98..
The uptake of these resistant bacteria can then happen through the food chain, when humans later consume these plants Antibiotic Resistance Threats in the United States. Centers for Disease Control and Prevention, 2013.
(http://www.cdc.gov/drugresistance/threat-report-2013/pdf/ar-threats-2013-508.pdf) or the contaminated flesh of animals and fish harbouring resistant bacteria Technical Report - The bacterial challenge: time to react
(https://ecdc.europa.eu/en/publications/Publications/0909_TER_The_Bacterial_Challenge_Time_to_React.pdf). As bacteria can easily reach water reserves, water distribution infrastructure is also a potential route for the spread of these bacteria Antimicrobial resistance: global report on surveillance. World Health Organisation, 2014.
(http://www.who.int/drugresistance/documents/AMR_report_Web_slide_set.pdf?ua=1). Even wildlife, insects and other bugs are potential carriers of antibiotic resistant microbes Spellberg et al. Combating Antimicrobial Resistance:Policy Recommendations to Save Lives. Clinical Infectious Diseases 2011;52:397-428.
(http://cid.oxfordjournals.org/content/52/suppl_5/S397.full.pdf). Tourism, migration and food imports Burden of Antibiotic Resistance. Action on Antibiotic Resistance (ReAct), 2012.
(http://www.reactgroup.org/uploads/publications/react-publications/ReAct-facts-burden-of-antibiotic-resistance-May-2012.pdf) are nevertheless reported as the fastest way of spreading resistant strains of bacteria across borders.
At the healthcare facility level, resistant bacteria can spread by contact between patients or with healthcare staff, or through contaminated surfaces and medical devices.
Reservoirs of antibiotic-resistant bacteria
Foodborne transmission of resistant bacteria is a common route for the spread of antibiotic resistance. Treating livestock with antibiotics can also be detrimental for the farmers’ health, as they can acquire resistant bacteria from the animals and transmit them to others. Several studies have revealed high transmission rates of MRSA between animals and farm workers. Price LB, et al. Staphylococcus aureus CC398:Host Adaptation and Emergence of Methicillin Resistance in Livestock. mBio 2012;3:e00305-11. DOI:10.1128/mBio.00305-11
Resistant bacteria from human sources have been detected in sewage treatment plants, in treated water released into the environment and in sludge applied to farmland. The highest concentrations of antibiotics and resistant bacteria are recorded in effluent released from hospitals and drug manufacturing sites in developing countries. House of Parliament. Office of Science & Technology. Antibiotic Resistance in the Environment. Post Note Number 446, October 2013.