Epidemiology of resistance to antibiotics. Links between animals and humans. - Related Documents




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421001.0000Epidemiology of resistance to antibiotics. Links between animals and humans. An inevitable side effect of the use of antibiotics is the emergence and dissemination of resistant bacteria. Most retrospective and prospective studies show that after the introduction of an antibiotic not only the level of resistance of pathogenic bacteria, but also of commensal bacteria increases. Commensal bacteria constitute a reservior of resistance genes for (potentially) pathogenic bacteria. Their level of resistance is considered to be a good indicator for selection pressure by antibiotic use and for resistance problems to be expected in pathogens. Resistant commensal bacteria of food animals might contaminate, like zoonotic bacteria, meat (products) and so reach the intestinal tract of humans. Monitoring the prevalence of resistance in indicator bacteria such as faecal Escherichia coli and enterococci in different populations, animals, patients and healthy humans, makes it feasible to compare the prevalence of resistance and to detect transfer of resistant bacteria or resistance genes from animals to humans and vice versa. Only in countries that use or used avoparcin (a glycopeptide antibiotic, like vancomycin) as antimicrobial growth promoter (AMGP), is vancomycin resistance common in intestinal enterococci, not only in exposed animals, but also in the human population outside hospitals. Resistance genes against antibiotics, that are or have only been used in animals, i.e. nourseothricin, apramycin etc. were found soon after their introduction, not only in animal bacteria but also in the commensal flora of humans, in zoonotic pathogens like salmonellae, but also in strictly human pathogens, like shigellae. This makes it clear that not only clonal spread of resistant strains occurs, but also transfer of resistance genes between human and animal bacteria. Moreover, since the EU ban of avoparcin, a significant decrease has been observed in several European countries in the prevalence of vancomycin resistant enterococci in meat (products), in faecal samples of food animals and healthy humans, which underlines the role of antimicrobial usage in food animals in the selection of bacterial resistance and the transport of these resistances via the food chain to humans. To safeguard public health, the selection and dissemination of resistant bacteria from animals should be controlled. This can only be achieved by reducing the amounts of antibiotics used in animals. Discontinuing the practice of routinely adding AMGP to animal feeds would reduce the amounts of antibiotics used for animals in the EU by a minimum of 30% and in some member states even by 50%.200010794955
421110.9999Monitoring of antimicrobial resistance among food animals: principles and limitations. Large amounts of antimicrobial agents are in the production of food animals used for therapy and prophylactics of bacterial infections and in feed to promote growth. The use of antimicrobial agents causes problems in the therapy of infections through the selection for resistance among bacteria pathogenic for animals or humans. Current knowledge regarding the occurrence of antimicrobial resistance in food animals, the quantitative impact of the use of different antimicrobial agents on selection for resistance and the most appropriate treatment regimes to limit the development of resistance is incomplete. Programmes monitoring the occurrence and development of resistance are essential to determine the most important areas for intervention and to monitor the effects of interventions. When designing a monitoring programme it is important to decide on the purpose of the programme. Thus, there are major differences between programmes designed to detect changes in a national population, individual herds or groups of animals. In addition, programmes have to be designed differently according to whether the aim is to determine changes in resistance for all antimicrobial agents or only the antimicrobial agents considered most important in relation to treatment of humans. In 1995 a continuous surveillance for antimicrobial resistance among bacteria isolated from food animals was established in Denmark. Three categories of bacteria, indicator bacteria, zoonotic bacteria and animal pathogens are continuously isolated from broilers, cattle and pigs and tested for susceptibility to antimicrobial agents used for therapy and growth promotion by disc diffusion or minimal inhibitory concentration determinations. This programme will only detect changes on a national level. However, isolating the bacteria and testing for several antimicrobial agents will enable us to determine the effect of linkage of resistance. Since 1995 major differences in the consumption pattern of different antimicrobial agents have occurred in Denmark. The Danish monitoring programme has enabled us to determine the effect of these changes on the occurrence of resistance. The Danish monitoring is, however, not suited to determine changes on a herd level or to detect emergence of new types of resistance only occurring at a low level.200415525370
394320.9999Quinolone resistance in the food chain. Antimicrobials are used in pet animals and in animal husbandry for prophylactic and therapeutic reasons and also as growth promoters, causing selective pressure on bacteria of animal origin. The impact of quinolones or quinolone-resistant bacteria on the management of human infections may be associated with three different scenarios. (i) Quinolone-resistant zoonotic bacterial pathogens are selected and food is contaminated during slaughter and/or preparation. (ii) Quinolone-resistant bacteria non-pathogenic to humans are selected in the animal. When the contaminated food is ingested, the bacteria may transfer resistance determinants to other bacteria in the human gut (commensal and potential pathogens). And (iii) quinolones remain in residues of food products, which may allow the selection of antibiotic-resistant bacteria after the food is consumed. In this review, we analyse the abovementioned aspects, emphasising the molecular basis of quinolone resistance in Escherichia coli, Salmonella spp. and Campylobacter spp.200818308515
412030.9999Transfer of antibiotic resistant bacteria from animals to man. Antibiotic resistance develops in zoonotic bacteria in response to antibiotics used in food animals. A close association exists between the amounts of antibiotics used and the levels of resistance observed. The classes of antibiotics routinely used for treatment of human infections are also used for animals either for therapy or for growth promotion. Antibiotic resistance in zoonotic bacteria constitute a public health hazard, primarily through the increased risk of treatment failures. This paper describes the zoonotic bacteria, salmonella, campylobacter, yersinia and entero-haemorrhagic E. coli (EHEC). Infections with these agents do not generally require antibiotic therapy, but in some cases antibiotics are essential to obtain a successful cure. The levels and types of resistance observed in zoonotic bacteria in some countries, especially the increasing levels of fluoroquinolone resistance in salmonella and campylobacter, gives cause for concern. The principles of controlling resistance development involve infection control at herd level and prudent use of antibiotics.199910783717
421340.9999Fluoroquinolone resistance of Escherichia coli and Salmonella from healthy livestock and poultry in the EU. The potential for transmission of antibiotic-resistant enteric zoonotic bacteria from animals to humans has been a public health concern for several decades. Bacteria carrying antibiotic resistance genes found in the intestinal tract of food animals can contaminate carcasses and may lead to food-borne disease in humans that may not respond to antibiotic treatment. It is consequently important to monitor changes in antimicrobial susceptibility of zoonotic and commensal organism; in this context, there are a number of veterinary monitoring programmes that collect bacteria in food-producing animals at slaughter and determine their susceptibility against antibiotics relevant for human medicine. The data generated are part of the risk analysis for potential food-borne transmission of resistance. There has been much debate about the use of fluoroquinolones in veterinary medicine, and so, this review will consider the fluoroquinolone data from two surveys and compare them to national surveillance programmes. At the outset, it must be pointed out that there is, however, a lack of agreement between several programmes on what is meant by the term 'fluoroquinolone resistance' through use of different definitions of resistance and different resistance breakpoints. An additional aim of this paper is to clarify some of those definitions. Despite the debate about the contribution of antibiotic use in veterinary medicine to the overall resistance development in human pathogens, the data suggest that clinical resistance to fluoroquinolones in Escherichia coli and nontyphoidal Salmonella is generally uncommon, except for a few countries. Ongoing surveillance will continue to monitor the situation and identify whether this situation changes within the respective animal populations. For the benefit of both the epidemiologist and the clinician, it would be strongly advantageous that national monitoring surveys report both percentages of clinical resistance and decreased susceptibility.201222066763
421550.9999Antibiotic usage in animals: impact on bacterial resistance and public health. Antibiotic use whether for therapy or prevention of bacterial diseases, or as performance enhancers will result in antibiotic resistant micro-organisms, not only among pathogens but also among bacteria of the endogenous microflora of animals. The extent to which antibiotic use in animals will contribute to the antibiotic resistance in humans is still under much debate. In addition to the veterinary use of antibiotics, the use of these agents as antimicrobial growth promoters (AGP) greatly influences the prevalence of resistance in animal bacteria and a poses risk factor for the emergence of antibiotic resistance in human pathogens. Antibiotic resistant bacteria such as Escherichia coli, Salmonella spp., Campylobacter spp. and enterococci from animals can colonise or infect the human population via contact (occupational exposure) or via the food chain. Moreover, resistance genes can be transferred from bacteria of animals to human pathogens in the intestinal flora of humans. In humans, the control of resistance is based on hygienic measures: prevention of cross contamination and a decrease in the usage of antibiotics. In food animals housed closely together, hygienic measures, such as prevention of oral-faecal contact, are not feasible. Therefore, diminishing the need for antibiotics is the only possible way of controlling resistance in large groups of animals. This can be achieved by improvement of animal husbandry systems, feed composition and eradication of or vaccination against infectious diseases. Moreover, abolishing the use of antibiotics as feed additives for growth promotion in animals bred as a food source for humans would decrease the use of antibiotics in animals on a worldwide scale by nearly 50%. This would not only diminish the public health risk of dissemination of resistant bacteria or resistant genes from animals to humans, but would also be of major importance in maintaining the efficacy of antibiotics in veterinary medicine.199910551432
393660.9999Impact of antibiotic use in the swine industry. Antibiotic resistance in bacteria associated with pigs not only affects pig production but also has an impact on human health through the transfer of resistant organisms and associated genes via the food chain. This can compromise treatment of human infections. In the past most attention was paid to glycopeptide and streptogramin resistance in enterococci, fluoroquinolone resistance in campylobacter and multi-drug resistance in Escherichia coli and salmonella. While these are still important the focus has shifted to ESBL producing organisms selected by the use of ceftiofur and cefquinome in pigs. In addition Livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) suddenly emerged in 2007. We also need to consider multi-resistant strains of Streptococcus suis. Environmental contamination arising from piggery wastewater and spreading of manure slurry on pastures is also a growing problem.201424959754
389770.9999The use of aminoglycosides in animals within the EU: development of resistance in animals and possible impact on human and animal health: a review. Aminoglycosides (AGs) are important antibacterial agents for the treatment of various infections in humans and animals. Following extensive use of AGs in humans, food-producing animals and companion animals, acquired resistance among human and animal pathogens and commensal bacteria has emerged. Acquired resistance occurs through several mechanisms, but enzymatic inactivation of AGs is the most common one. Resistance genes are often located on mobile genetic elements, facilitating their spread between different bacterial species and between animals and humans. AG resistance has been found in many different bacterial species, including those with zoonotic potential such as Salmonella spp., Campylobacter spp. and livestock-associated MRSA. The highest risk is anticipated from transfer of resistant enterococci or coliforms (Escherichia coli) since infections with these pathogens in humans would potentially be treated with AGs. There is evidence that the use of AGs in human and veterinary medicine is associated with the increased prevalence of resistance. The same resistance genes have been found in isolates from humans and animals. Evaluation of risk factors indicates that the probability of transmission of AG resistance from animals to humans through transfer of zoonotic or commensal foodborne bacteria and/or their mobile genetic elements can be regarded as high, although there are no quantitative data on the actual contribution of animals to AG resistance in human pathogens. Responsible use of AGs is of great importance in order to safeguard their clinical efficacy for human and veterinary medicine.201931002332
394180.9999Antibiotic Resistance among Gastrointestinal Bacteria in Broilers: A Review Focused on Enterococcus spp. and Escherichia coli. Chickens can acquire bacteria at different stages, and bacterial diversity can occur due to production practices, diet, and environment. The changes in consumer trends have led to increased animal production, and chicken meat is one of the most consumed meats. To ensure high levels of production, antimicrobials have been used in livestock for therapeutic purposes, disease prevention, and growth promotion, contributing to the development of antimicrobial resistance across the resident microbiota. Enterococcus spp. and Escherichia coli are normal inhabitants of the gastrointestinal microbiota of chickens that can develop strains capable of causing a wide range of diseases, i.e., opportunistic pathogens. Enterococcus spp. isolated from broilers have shown resistance to at least seven classes of antibiotics, while E. coli have shown resistance to at least four. Furthermore, some clonal lineages, such as ST16, ST194, and ST195 in Enterococcus spp. and ST117 in E. coli, have been identified in humans and animals. These data suggest that consuming contaminated animal-source food, direct contact with animals, or environmental exposure can lead to the transmission of antimicrobial-resistant bacteria. Therefore, this review focused on Enterococcus spp. and E. coli from the broiler industry to better understand how antibiotic-resistant strains have emerged, which antibiotic-resistant genes are most common, what clonal lineages are shared between broilers and humans, and their impact through a One Health perspective.202337106925
433590.9999Veterinary drug usage and antimicrobial resistance in bacteria of animal origin. In the production of food animals, large amounts of antimicrobial agents are used for therapy and prophylaxis of bacterial infections and in feed to promote growth. There are large variations in the amounts of antimicrobial agents used to produce the same amount of meat among the different European countries, which leaves room for considerable reductions in some countries. The emergence of resistant bacteria and resistance genes due to the use of antimicrobial agents are well documented. In Denmark it has been possible to reduce the usage of antimicrobial agents for food animals significantly and in general decreases in resistance have followed. Guidelines for prudent use of antimicrobial agents may help to slow down the selection for resistance and should be based on knowledge regarding the normal susceptibility patterns of the causative agents and take into account the potential problems for human health. Current knowledge regarding the occurrence of antimicrobial resistance in food animals, the quantitative impact of the use of different antimicrobial agents on selection of resistance and the most appropriate treatment regimes to limit the development of resistance is incomplete. Programmes monitoring the occurrence and development of resistance and consumption of antimicrobial agents are strongly desirable, as is research into the most appropriate ways to use antimicrobial agents in veterinary medicine.200515755309
4217100.9999Antimicrobial use and resistance in animals. Food animals in the United States are often exposed to antimicrobials to treat and prevent infectious disease or to promote growth. Many of these antimicrobials are identical to or closely resemble drugs used in humans. Precise figures for the quantity of antimicrobials used in animals are not publicly available in the United States, and estimates vary widely. Antimicrobial resistance has emerged in zoonotic enteropathogens (e.g., Salmonella spp., Campylobacter spp.), commensal bacteria (e.g., Escherichia coli, enterococci), and bacterial pathogens of animals (e.g., Pasteurella, Actinobacillus spp.), but the prevalence of resistance varies. Antimicrobial resistance emerges from the use of antimicrobials in animals and the subsequent transfer of resistance genes and bacteria among animals and animal products and the environment. To slow the development of resistance, some countries have restricted antimicrobial use in feed, and some groups advocate similar measures in the United States. Alternatives to growth-promoting and prophylactic uses of antimicrobials in agriculture include improved management practices, wider use of vaccines, and introduction of probiotics. Monitoring programs, prudent use guidelines, and educational campaigns provide approaches to minimize the further development of antimicrobial resistance.200211988879
4216110.9999Antimicrobial Resistance in the Food Chain in the European Union. Consumers require safety foods but without losing enough supply and low prices. Food concerns about antimicrobial residues and antimicrobial-resistant (AMR) bacteria are not usually appropriately separated and could be perceived as the same problem. The monitoring of residues of antimicrobials in animal food is well established at different levels (farm, slaughterhouse, and industry), and it is preceded by the legislation of veterinary medicines where maximum residues limits are required for medicines to be used in food animal. Following the strategy of the World Health Organization, one of the proposed measures consists in controlling the use of critical antibiotics. The European Union surveillance program currently includes the animal species with the highest meat production (pigs, chickens, turkeys, and cattle) and the food derived from them, investigating antimicrobial resistance of zoonotic (Salmonella and Campylobacter) and indicator (Escherichia coli and enterococci) bacteria. AMR mechanisms encoded by genes have a greater impact on transfer than mutations. Sometimes these genes are found in mobile genetic elements such as plasmids, transposons, or integrons, capable of passing from one bacterium to another by horizontal transfer. It is important to know that depending on how the resistance mechanism is transferred, the power of dissemination is different. By vertical transfer of the resistance gene, whatever its origin, will be transmitted to the following generations. In the case of horizontal transfer, the resistance gene moves to neighboring bacteria and therefore the range of resistance can be much greater.201830077219
4212120.9999Review on the occurrence of the mcr-1 gene causing colistin resistance in cow's milk and dairy products. Both livestock farmers and the clinic use significant amount of antibiotics worldwide, in many cases the same kind. Antibiotic resistance is not a new phenomenon, however, it is a matter of concern that resistance genes (mcr - Mobilized Colistin Resistance - genes) that render last-resort drugs (Colistin) ineffective, have already evolved. Nowadays, there is a significant consumption of milk and dairy products, which, if not treated properly, can contain bacteria (mainly Gram-negative bacteria). We collected articles and reviews in which Gram-negative bacteria carrying the mcr-1 gene have been detected in milk, dairy products, or cattle. Reports have shown that although the incidence is still low, unfortunately the gene has been detected in some dairy products on almost every continent. In the interest of our health, the use of colistin in livestock farming must be banned as soon as possible, and new treatments should be applied so that we can continue to have a chance in fighting multidrug-resistant bacteria in human medicine.202133898852
4183130.9999Human health impact from antimicrobial use in food animals. There is accumulating evidence that the use of antimicrobials in food-producing animals has adverse human health consequences. The use of antibiotics in food animals selects for resistant pathogens and resistance genes that may be transferred to humans through the consumption or handling of foods of animal origin. Recent studies have demonstrated that antimicrobial-resistance among foodborne bacteria may cause excess cases of illness, prolonged duration of illness, and increased rates of bacteremia, hospitalization, and death. The continued availability of safe and effective antimicrobials for humans and animals depends upon the responsible use of these products.200415620055
3938140.9999Human health hazards associated with the administration of antimicrobials to slaughter animals. Part II. An assessment of the risks of resistant bacteria in pigs and pork. Risks for the consumer regarding the acquisition of resistant bacteria and/or resistance genes via the consumption of pork are discussed. In general, Salmonella spp. and Escherichia coli that originate from animals do not easily transfer their resistance genes to the resident intestinal flora of humans. The prevalence of resistant E. coli in humans seems more associated with being a vegetarian (odds ratio (OR) 1.89) than with the consumption of meat and meat products. Other risk factors are treatment with antimicrobials (OR 2-5), becoming hospitalized (OR 5.93), or working in a health setting (OR 4.38). In the Netherlands, annually an estimated 45,000 people (0-150,000) become a carrier of resistant E. coli and/or resistance genes that ori ginate from pigs, while an estimated 345,000 persons (175,000-600,000) become a carrier of resistant E. coli and/or resistance genes that originate from hospitals, e.g. other patients. Any problems with resistant Salmonella spp. that stem from pigs are, in fact, an integral part of the total problem of food-borne salmonellosis. Sometimes there are outbreaks of a specific multi-resistant clone of S. typhimurium that causes problems in both farm animals and humans. The probability that in the next 30 years there is no or maximally one outbreak of a specific clone that originates from pig herds is estimated at about 75%. Antimicrobials used as a growth promoter can have a measurable influence on the prevalence of resistant bacteria. The likely chain of events regarding avoparcin and the selection and dissemination of resistance against vancomycin in the enterococci gives the impression that the impact of the use of antimicrobials in animals on the prevalence of resistance in humans is largely determined by whether resistance genes are, or become, located on a self-transferable transposon. Furthermore, consumer health risks of antimicrobials used in slaughter pigs are mainly determined by the selection and dissemination of bacterial resistance and much less by the toxicological properties of any residues in pork. It is also concluded that most of the problems with resistant bacteria in humans are associated with the medical use of antimicrobials, and that the impact of particularly the veterinary use of antimicrobials is limited. However, the impact of antimicrobials used as a feed additive appears to be much greater than that of antimicrobials used for strictly veterinary purposes. The use of antimicrobials as a feed additive should therefore be seriously reconsidered.200111205995
3896150.9999Antimicrobial resistance genes in bacteria from animal-based foods. Antimicrobial resistance is a worldwide public health threat. Farm animals are important sources of bacteria containing antimicrobial resistance genes (ARGs). Although the use of antimicrobials in aquaculture and livestock has been reduced in several countries, these compounds are still routinely applied in animal production, and contribute to ARGs emergence and spread among bacteria. ARGs are transmitted to humans mainly through the consumption of products of animal origin (PAO). Bacteria can present intrinsic resistance, and once antimicrobials are administered, this resistance may be selected and multiply. The exchange of genetic material is another mechanism used by bacteria to acquire resistance. Some of the main ARGs found in bacteria present in PAO are the bla, mcr-1, cfr and tet genes, which are directly associated to antibiotic resistance in the human clinic.202032762867
3945160.9999Vancomycin-resistant enterococci: why are they here, and where do they come from? Vancomcyin-resistant enterococci (VRE) have emerged as nosocomial pathogens in the past 10 years, causing epidemiological controversy. In the USA, colonisation with VRE is endemic in many hospitals and increasingly causes infection, but colonisation is absent in healthy people. In Europe, outbreaks still happen sporadically, usually with few serious infections, but colonisation seems to be endemic in healthy people and farm animals. Vancomycin use has been much higher in the USA, where emergence of ampicillin-resistant enterococci preceded emergence of VRE, making them very susceptible to the selective effects of antibiotics. In Europe, avoparcin, a vancomycin-like glycopeptide, has been widely used in the agricultural industry, explaining the community reservoir in European animals. Avoparcin has not been used in the USA, which is consistent with the absence of colonisation in healthy people. From the European animal reservoir, VRE and resistance genes have spread to healthy human beings and hospitalised patients. However, certain genogroups of enterococci in both continents seem to be more capable of causing hospital outbreaks, perhaps because of the presence of a specific virulence factor, the variant esp gene. By contrast with the evidence of a direct link between European animal and human reservoirs, the origin of American resistance genes remains to be established. Considering the spread of antibiotic-resistant bacteria and resistance genes, the emergence of VRE has emphasised the non-existence of boundaries between hospitals, between people and animals, between countries, and probably between continents.200111871804
3937170.9999Design of a system for monitoring antimicrobial resistance in pathogenic, zoonotic and indicator bacteria from food animals. DANMAP is a Danish programme for integrated monitoring of and research on antimicrobial resistance in bacteria from food animals, food and humans. The paper describes how bacteria from broilers, pigs, and cattle are collected, as well as the procedures for data handling and presentation of results. The bacteria from animals include certain pathogens, selected so that they are representative for submissions to Danish diagnostic laboratories, as well as zoonotic bacteria (Campylobacter, Salmonella and Yersinia) and indicator bacteria (E. coli, E. faecium and E. faecalis), from samples collected at abattoirs. The latter samples are selected so that they are representative of the respective animal populations. Therefore, the apparent prevalence of antimicrobial resistance in the populations may be calculated. The isolates are identified to species level and the results of susceptibility testing are stored as continuous variables. All isolates are maintained in a strain collection so that they are available for subsequent research projects. The data handling facilities makes it possible to present results as percent resistant isolates or as the apparent prevalence of resistance in the population, or alternatively as graphical distributions of mm inhibition zones or MIC values. Computer routines have been established that make it possible to detect specific phenotypic expressions of resistance that may be of particular interest.199910783720
3947180.9999Human health hazard from antimicrobial-resistant enterococci in animals and food. The use of antimicrobial agents in the modern farm industry has created a reservoir of resistant bacteria in food animals. Foods of animal origin are often contaminated with enterococci that are likely to contribute resistance genes, virulence factors, or other properties to enterococci IN humans. The potential hazard to human health from antimicrobial-resistant enterococci in animals is questioned by some scientists because of evidence of host specificity of enterococci. Similarly, the occurrences of specific nosocomial clones of enterococci in hospitals have lead to the misconception that antimicrobial-resistant animal enterococci should be disregarded as a human health hazard. On the basis of review of the literature, we find that neither the results provided by molecular typing that classify enterococci as host-specific organisms nor the occurrence of specific nosocomial clones of enterococci provide reasons to change the current view that antimicrobial-resistant enterococci from animals pose a threat to human health. On the contrary, antimicrobial resistance genes appear to spread freely between enterococci from different reservoirs, irrespective of their apparent host association.200616941376
4214190.9999Antimicrobial usage and resistance in beef production. Antimicrobials are critical to contemporary high-intensity beef production. Many different antimicrobials are approved for beef cattle, and are used judiciously for animal welfare, and controversially, to promote growth and feed efficiency. Antimicrobial administration provides a powerful selective pressure that acts on the microbial community, selecting for resistance gene determinants and antimicrobial-resistant bacteria resident in the bovine flora. The bovine microbiota includes many harmless bacteria, but also opportunistic pathogens that may acquire and propagate resistance genes within the microbial community via horizontal gene transfer. Antimicrobial-resistant bovine pathogens can also complicate the prevention and treatment of infectious diseases in beef feedlots, threatening the efficiency of the beef production system. Likewise, the transmission of antimicrobial resistance genes to bovine-associated human pathogens is a potential public health concern. This review outlines current antimicrobial use practices pertaining to beef production, and explores the frequency of antimicrobial resistance in major bovine pathogens. The effect of antimicrobials on the composition of the bovine microbiota is examined, as are the effects on the beef production resistome. Antimicrobial resistance is further explored within the context of the wider beef production continuum, with emphasis on antimicrobial resistance genes in the food chain, and risk to the human population.201627999667