Zinc and copper in animal feed - development of resistance and co-resistance to antimicrobial agents in bacteria of animal origin. - Related Documents




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412801.0000Zinc and copper in animal feed - development of resistance and co-resistance to antimicrobial agents in bacteria of animal origin. Farmed animals such as pig and poultry receive additional Zn and Cu in their diets due to supplementing elements in compound feed as well as medical remedies. Enteral bacteria in farmed animals are shown to develop resistance to trace elements such as Zn and Cu. Resistance to Zn is often linked with resistance to methicillin in staphylococci, and Zn supplementation to animal feed may increase the proportion of multiresistant E. coli in the gut. Resistance to Cu in bacteria, in particular enterococci, is often associated with resistance to antimicrobial drugs like macrolides and glycopeptides (e.g. vancomycin). Such resistant bacteria may be transferred from the food-producing animals to humans (farmers, veterinarians, and consumers). Data on dose-response relation for Zn/Cu exposure and resistance are lacking; however, it seems more likely that a resistance-driven effect occurs at high trace element exposure than at more basal exposure levels. There is also lack of data which could demonstrate whether Zn/Cu-resistant bacteria may acquire antibiotic resistance genes/become antibiotics resistant, or if antibiotics-resistant bacteria are more capable to become Zn/Cu resistant than antibiotics-susceptible bacteria. Further research is needed to elucidate the link between Zn/Cu and antibiotic resistance in bacteria.201425317117
770510.9999Oxytetracycline reduces the diversity of tetracycline-resistance genes in the Galleria mellonella gut microbiome. BACKGROUND: Clinically-relevant multidrug resistance is sometimes present in bacteria not exposed to human-made antibiotics, in environments without extreme selective pressures, such as the insect gut. The use of antibiotics on naïve microbiomes often leads to decreased microbe diversity and increased antibiotic resistance. RESULTS: Here we investigate the impact of antibiotics on the insect gut microbiome by identifying tetracycline-resistance genes in the gut bacteria of greater wax moth (Galleria mellonella) larvae, feeding on artificial food containing oxytetracycline. We determined that G. mellonella can be raised on artificial food for over five generations and that the insects tolerate low doses of antibiotics in their diets, but doses of oxytetracycline higher than sub-inhibitory lead to early larval mortality. In our experiments, greater wax moth larvae had a sparse microbiome, which is consistent with previous findings. Additionally, we determined that the microbiome of G. mellonella larvae not exposed to antibiotics carries a number of tetracycline-resistance genes and some of that diversity is lost upon exposure to strong selective pressure. CONCLUSIONS: We show that G. mellonella larvae can be raised on artificial food, including antibiotics, for several generations and that the microbiome can be sampled. We show that, in the absence of antibiotics, the insect gut microbiome can maintain a diverse pool of tetracycline-resistance genes. Selective pressure, from exposure to the antibiotic oxytetracycline, leads to microbiome changes and alteration in the tetracycline-resistance gene pool.201830594143
412920.9998Residential Bacteria on Surfaces in the Food Industry and Their Implications for Food Safety and Quality. Surface hygiene is commonly measured as a part of the quality system of food processing plants, but as the bacteria present are commonly not identified, their roles for food quality and safety are not known. Here, we review the identity of residential bacteria and characteristics relevant for survival and growth in the food industry along with potential implications for food safety and quality. Sampling after cleaning and disinfection increases the likelihood of targeting residential bacteria. The increasing use of sequencing technologies to identify bacteria has improved knowledge about the bacteria present in food premises. Overall, nonpathogenic Gram-negative bacteria, especially Pseudomonas spp., followed by Enterobacteriaceae and Acinetobacter spp. dominate on food processing surfaces. Pseudomonas spp. persistence is likely due to growth at low temperatures, biofilm formation, tolerance to biocides, and low growth requirements. Gram-positive bacteria are most frequently found in dairies and in dry production environments. The residential bacteria may end up in the final products through cross-contamination and may affect food quality. Such effects can be negative and lead to spoilage, but the bacteria may also contribute positively, as through spontaneous fermentation. Pathogenic bacteria present in food processing environments may interact with residential bacteria, resulting in both inhibitory and stimulatory effects on pathogens in multispecies biofilms. The residential bacterial population, or bacteriota, does not seem to be an important source for the transfer of antibiotic resistance genes to humans, but more knowledge is needed to verify this. If residential bacteria occur in high numbers, they may influence processes such as membrane filtration and corrosion.201733371605
412730.9998The Perfect Condition for the Rising of Superbugs: Person-to-Person Contact and Antibiotic Use Are the Key Factors Responsible for the Positive Correlation between Antibiotic Resistance Gene Diversity and Virulence Gene Diversity in Human Metagenomes. Human metagenomes with a high diversity of virulence genes tend to have a high diversity of antibiotic-resistance genes and vice-versa. To understand this positive correlation, we simulated the transfer of these genes and bacterial pathogens in a community of interacting people that take antibiotics when infected by pathogens. Simulations show that people with higher diversity of virulence and resistance genes took antibiotics long ago, not recently. On the other extreme, we find people with low diversity of both gene types because they took antibiotics recently-while antibiotics select specific resistance genes, they also decrease gene diversity by eliminating bacteria. In general, the diversity of virulence and resistance genes becomes positively correlated whenever the transmission probability between people is higher than the probability of losing resistance genes. The positive correlation holds even under changes of several variables, such as the relative or total diversity of virulence and resistance genes, the contamination probability between individuals, the loss rate of resistance genes, or the social network type. Because the loss rate of resistance genes may be shallow, we conclude that the transmission between people and antibiotic usage are the leading causes for the positive correlation between virulence and antibiotic-resistance genes.202134065307
382640.9998Co-resistance: an opportunity for the bacteria and resistance genes. Co-resistance involves transfer of several genes into the same bacteria and/or the acquisition of mutations in different genetic loci affecting different antimicrobials whereas pleiotropic resistance implies the same genetic event affecting several antimicrobials. There is an increasing prevalence of isolates with co-resistance which are over-represented within the so-called high-risk clones. Compensatory events avoid fitness cost of co-resistance, even in the absence of antimicrobials. Nevertheless, they might be selected by different antimicrobials and a single agent might select co-resistant isolates. This process, named as co-selection, is not avoided with cycling or mixing strategies of antimicrobial use. Co-resistance and co-selection processes increase the opportunity for persistence of the bacteria and resistance genes and should be considered when designing strategies for decreasing antimicrobial resistance.201121840259
428450.9998Overview on the role of heavy metals tolerance on developing antibiotic resistance in both Gram-negative and Gram-positive bacteria. Environmental health is a critical concern, continuously contaminated by physical and biological components (viz., anthropogenic activity), which adversely affect on biodiversity, ecosystems and human health. Nonetheless, environmental pollution has great impact on microbial communities, especially bacteria, which try to evolve in changing environment. For instance, during the course of adaptation, bacteria easily become resistance to antibiotics and heavy metals. Antibiotic resistance genes are now one of the most vital pollutants, provided as a source of frequent horizontal gene transfer. In this review, the environmental cause of multidrug resistance (MDR) that was supposed to be driven by either heavy metals or combination of environmental factors was essentially reviewed, especially focussed on the correlation between accumulation of heavy metals and development of MDR by bacteria. This kind of correlation was seemed to be non-significant, i.e. paradoxical. Gram-positive bacteria accumulating much of toxic heavy metal (i.e. highly stress tolerance) were unlikely to become MDR, whereas Gram-negative bacteria that often avoid accumulation of toxic heavy metal by efflux pump systems were come out to be more prone to MDR. So far, other than antibiotic contaminant, no such available data strongly support the direct influence of heavy metals in bacterial evolution of MDR; combinations of factors may drive the evolution of antibiotic resistance. Therefore, Gram-positive bacteria are most likely to be an efficient member in treatment of industrial waste water, especially in the removal of heavy metals, perhaps inducing the less chance of antibiotic resistance pollution in the environment.202133811263
465160.9998Long-term shifts in patterns of antibiotic resistance in enteric bacteria. Several mechanisms are responsible for the ability of microorganisms to tolerate antibiotics, and the incidence of resistance to these compounds within bacterial species has increased since the commercial use of antibiotics became widespread. To establish the extent of and changes in the diversity of antibiotic resistance patterns in natural populations, we determined the MICs of five antibiotics for collections of enteric bacteria isolated from diverse hosts and geographic locations and during periods before and after commercial application of antibiotics began. All of the pre-antibiotic era strains were susceptible to high levels of these antibiotics, whereas 20% of strains from contemporary populations of Escherichia coli and Salmonella enterica displayed high-level resistance to at least one of the antibiotics. In addition to the increase in the frequency of high-level resistance, background levels, conferred by genes providing nonspecific low-level resistance to multiple antibiotics, were significantly higher among contemporary strains. Changes in the incidence and levels of antibiotic resistance are not confined to particular segments of the bacterial population and reflect responses to the increased exposure of bacteria to antimicrobial compounds over the past several decades.200011097921
399470.9998Environmental Biofilms as Reservoirs for Antimicrobial Resistance. Characterizing the response of microbial communities to a range of antibiotic concentrations is one of the strategies used to understand the impact of antibiotic resistance. Many studies have described the occurrence and prevalence of antibiotic resistance in microbial communities from reservoirs such as hospitals, sewage, and farm feedlots, where bacteria are often exposed to high and/or constant concentrations of antibiotics. Outside of these sources, antibiotics generally occur at lower, sub-minimum inhibitory concentrations (sub-MICs). The constant exposure to low concentrations of antibiotics may serve as a chemical "cue" that drives development of antibiotic resistance. Low concentrations of antibiotics have not yet been broadly described in reservoirs outside of the aforementioned environments, nor is the transfer and dissemination of antibiotic resistant bacteria and genes within natural microbial communities fully understood. This review will thus focus on low antibiotic-concentration environmental reservoirs and mechanisms that are important in the dissemination of antibiotic resistance to help identify key knowledge gaps concerning the environmental resistome.202134970233
422880.9998Resistance to antibiotics in the normal flora of animals. The normal bacterial flora contains antibiotic resistance genes to various degrees, even in individuals with no history of exposure to commercially prepared antibiotics. Several factors seem to increase the number of antibiotic-resistant bacteria in feces. One important factor is the exposure of the intestinal flora to antibacterial drugs. Antibiotics used as feed additives seem to play an important role in the development of antibiotic resistance in normal flora bacteria. The use of avoparcin as a feed additive has demonstrated that an antibiotic considered "safe" is responsible for increased levels of antibiotic resistance in the normal flora enterococci of animals fed with avoparcin and possibly in humans consuming products from these animals. However, other factors like stress from temperature, crowding, and management also seem to contribute to the occurrence of antibiotic resistance in normal flora bacteria. The normal flora of animals has been studied with respect to the development of antibiotic resistance over four decades, but there are few studies with the intestinal flora as the main focus. The results of earlier studies are valuable when focused against the recent understanding of mobile genetics responsible for bacterial antibiotic resistance. New studies should be undertaken to assess whether the development of antibiotic resistance in the normal flora is directly linked to the dramatic increase in antibiotic resistance of bacterial pathogens. Bacteria of the normal flora, often disregarded scientifically, should be studied with the intention of using them as active protection against infectious diseases and thereby contributing to the overall reduction of use of antibioties in both animals and humans.200111432415
380090.9998Alterations of Salmonella enterica Serovar Typhimurium Antibiotic Resistance under Environmental Pressure. Microbial horizontal gene transfer is a continuous process that shapes bacterial genomic adaptation to the environment and the composition of concurrent microbial ecology. This includes the potential impact of synthetic antibiotic utilization in farm animal production on overall antibiotic resistance issues; however, the mechanisms behind the evolution of microbial communities are not fully understood. We explored potential mechanisms by experimentally examining the relatedness of phylogenetic inference between multidrug-resistant Salmonella enterica serovar Typhimurium isolates and pathogenic Salmonella Typhimurium strains based on genome-wide single-nucleotide polymorphism (SNP) comparisons. Antibiotic-resistant S Typhimurium isolates in a simulated farm environment barely lost their resistance, whereas sensitive S Typhimurium isolates in soils gradually acquired higher tetracycline resistance under antibiotic pressure and manipulated differential expression of antibiotic-resistant genes. The expeditious development of antibiotic resistance and the ensuing genetic alterations in antimicrobial resistance genes in S Typhimurium warrant effective actions to control the dissemination of Salmonella antibiotic resistance.IMPORTANCE Antibiotic resistance is attributed to the misuse or overuse of antibiotics in agriculture, and antibiotic resistance genes can also be transferred to bacteria under environmental stress. In this study, we report a unidirectional alteration in antibiotic resistance from susceptibility to increased resistance. Highly sensitive Salmonella enterica serovar Typhimurium isolates from organic farm systems quickly acquired tetracycline resistance under antibiotic pressure in simulated farm soil environments within 2 weeks, with expression of antibiotic resistance-related genes that was significantly upregulated. Conversely, originally resistant S Typhimurium isolates from conventional farm systems lost little of their resistance when transferred to environments without antibiotic pressure. Additionally, multidrug-resistant S Typhimurium isolates genetically shared relevancy with pathogenic S Typhimurium isolates, whereas susceptible isolates clustered with nonpathogenic strains. These results provide detailed discussion and explanation about the genetic alterations and simultaneous acquisition of antibiotic resistance in S Typhimurium in agricultural environments.201830054356
4188100.9998Use of antimicrobial agents in aquaculture. The aquaculture industry has grown dramatically, and plays an important role in the world's food supply chain. Antimicrobial resistance in bacteria associated with food animals receives much attention, and drug use in aquaculture is also an important issue. There are many differences between aquatic and terrestrial management systems, such as the methods used for administration of drugs. Unique problems are related to the application of drugs in aquatic environments. Residual drugs in fish products can affect people who consume them, and antimicrobials released into aquatic environments can select for resistant bacteria. Moreover, these antimicrobial-resistant bacteria, or their resistance genes, can be transferred to humans. To decrease the risks associated with the use of antimicrobials, various regulations have been developed. In addition, it is necessary to prevent bacterial diseases in aquatic animals by vaccination, to improve culture systems, and to monitor the amount of antimicrobial drugs used and the prevalence of antimicrobial-resistant bacteria.201222849275
4215110.9998Antibiotic 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
3859120.9998Co-selection of antibiotic resistance via copper shock loading on bacteria from a drinking water bio-filter. Heavy metal contamination of source water frequently occurred in developing countries as a result of accidents. To address the problems, most of the previous studies have focused on engineering countermeasures. In this study, we investigated the effects of heavy metals, particularly copper, on the development of antibiotic resistance by establishing a copper shock loading test. Results revealed that co-selection occurred rapidly within 6 h. Copper, at the levels of 10 and 100 mg/L, significantly increased bacterial resistance to the antibiotics tested, including rifampin, erythromycin, kanamycin, and a few others. A total of 117 antimicrobial-resistance genes were detected from 12 types of genes, and the relative abundance of most genes (particularly mobile genetic elements intⅠand transposons) was markedly enriched by at least one fold. Furthermore, the copper shock loading altered the bacterial community. Numerous heavy metal and antibiotic resistant strains were screened out and enriched. These strains are expected to enhance the overall level of resistance. More noticeably, the majority of the co-selected antibiotic resistance could sustain for at least 20 h in the absence of copper and antimicrobial drugs. Resistance to vancomycin, erythromycin and lincomycin even could remain for 7 days. The prominent selection pressure by the copper shock loading implies that a real accident most likely poses similar impacts on the water environment. An accidental release of heavy metals would not only cause harm to the ecological environment, but also contribute to the development of bacterial antibiotic resistance. Broader concerns should be raised about the biological risks caused by sudden releases of pollutants by accidents.201829059628
4123130.9998The Invisible Threat of Antibiotic Resistance in Food. The continued and improper use of antibiotics has resulted in the emergence of antibiotic resistance (AR). The dissemination of antibiotic-resistant microorganisms occurs via a multitude of pathways, including the food supply. The failure to comply with the regulatory withdrawal period associated with the treatment of domestic animals or the illicit use of antibiotics as growth promoters has contributed to the proliferation of antibiotic-resistant bacteria in meat and dairy products. It was demonstrated that not only do animal and human pathogens act as donors of antibiotic resistance genes, but also that lactic acid bacteria can serve as reservoirs of genes encoding for antibiotic resistance. Consequently, the consumption of fermented foods also presents a potential conduit for the dissemination of AR. This review provides an overview of the potential for the transmission of antibiotic resistance in a range of traditional and novel foods. The literature data reveal that foodborne microbes can be a significant factor in the dissemination of antibiotic resistance.202540149061
4122140.9998Antimicrobial resistance in the food chain: a review. Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public health, as they increase the gene pool from which pathogenic bacteria can pick up resistance traits. Food can be contaminated with antimicrobial resistant bacteria and/or antimicrobial resistance genes in several ways. A first way is the presence of antibiotic resistant bacteria on food selected by the use of antibiotics during agricultural production. A second route is the possible presence of resistance genes in bacteria that are intentionally added during the processing of food (starter cultures, probiotics, bioconserving microorganisms and bacteriophages). A last way is through cross-contamination with antimicrobial resistant bacteria during food processing. Raw food products can be consumed without having undergone prior processing or preservation and therefore hold a substantial risk for transfer of antimicrobial resistance to humans, as the eventually present resistant bacteria are not killed. As a consequence, transfer of antimicrobial resistance genes between bacteria after ingestion by humans may occur. Under minimal processing or preservation treatment conditions, sublethally damaged or stressed cells can be maintained in the food, inducing antimicrobial resistance build-up and enhancing the risk of resistance transfer. Food processes that kill bacteria in food products, decrease the risk of transmission of antimicrobial resistance.201323812024
3830150.9998Resistance Gene Carriage Predicts Growth of Natural and Clinical Escherichia coli Isolates in the Absence of Antibiotics. Bacterial pathogens that carry antibiotic resistance alleles sometimes pay a cost in the form of impaired growth in antibiotic-free conditions. This cost of resistance is expected to be a key parameter for understanding how resistance spreads and persists in pathogen populations. Analysis of individual resistance alleles from laboratory evolution and natural isolates has shown they are typically costly, but these costs are highly variable and influenced by genetic variation at other loci. It therefore remains unclear how strongly resistance is linked to impaired antibiotic-free growth in bacteria from natural and clinical scenarios, where resistance alleles are likely to coincide with other types of genetic variation. To investigate this, we measured the growth of 92 natural and clinical Escherichia coli isolates across three antibiotic-free environments. We then tested whether variation of antibiotic-free growth among isolates was predicted by their resistance to 10 antibiotics, while accounting for the phylogenetic structure of the data. We found that isolates with similar resistance profiles had similar antibiotic-free growth profiles, but it was not simply that higher average resistance was associated with impaired growth. Next, we used whole-genome sequences to identify antibiotic resistance genes and found that isolates carrying a greater number of resistance gene types grew relatively poorly in antibiotic-free conditions, even when the resistance genes they carried were different. This suggests that the resistance of bacterial pathogens is linked to growth costs in nature, but it is the total genetic burden and multivariate resistance phenotype that predict these costs, rather than individual alleles or mean resistance across antibiotics.IMPORTANCE Managing the spread of antibiotic resistance in bacterial pathogens is a major challenge for global public health. Central to this challenge is understanding whether resistance is linked to impaired bacterial growth in the absence of antibiotics, because this determines whether resistance declines when bacteria are no longer exposed to antibiotics. We studied 92 isolates of the key bacterial pathogen Escherichia coli; these isolates varied in both their antibiotic resistance genes and other parts of the genome. Taking this approach, rather than focusing on individual genetic changes associated with resistance as in much previous work, revealed that growth without antibiotics was linked to the number of specialized resistance genes carried and the combination of antibiotics to which isolates were resistant but was not linked to average antibiotic resistance. This approach provides new insights into the genetic factors driving the long-term persistence of antibiotic-resistant bacteria, which is important for future efforts to predict and manage resistance.201930530714
4118160.9998Antimicrobial resistance in livestock. Antimicrobial resistance may become a major problem in veterinary medicine as a consequence of the intensive use and misuse of antimicrobial drugs. Related problems are now arising in human medicine, such as the appearance of multi-resistant food-borne pathogens. Product characteristics, dose, treatment interval and duration of treatment influence the selection pressure for antimicrobial drug resistance. There are theoretical, experimental and clinical indications that the emergence of de novo resistance in a pathogenic population can be prevented by minimizing the time that suboptimal drug levels are present in the infected tissue compartment. Until recently, attention has been focused on target pathogens. However, it should be kept in mind that when antimicrobial drugs are used in an individual, resistance selection mainly affects the normal body flora. In the long term, this is at least equally important as resistance selection in the target pathogens, as the horizontal transfer of resistance genes converts almost all pathogenic bacteria into potential recipients for antimicrobial resistance. Other factors contributing to the epidemiology of antimicrobial resistance are the localization and size of the microbial population, and the age, immunity and contact intensity of the host. In livestock, dynamic herd-related resistance patterns have been observed in different animal species.200312667177
9629170.9998Costs of antibiotic resistance genes depend on host strain and environment and can influence community composition. Antibiotic resistance genes (ARGs) benefit host bacteria in environments containing corresponding antibiotics, but it is less clear how they are maintained in environments where antibiotic selection is weak or sporadic. In particular, few studies have measured if the direct effect of ARGs on host fitness is fixed or if it depends on the host strain, perhaps marking some ARG-host combinations as selective refuges that can maintain ARGs in the absence of antibiotic selection. We quantified the fitness effects of six ARGs in 11 diverse Escherichia spp. strains. Three ARGs (bla(TEM-116), cat and dfrA5, encoding resistance to β-lactams, chloramphenicol, and trimethoprim, respectively) imposed an overall cost, but all ARGs had an effect in at least one host strain, reflecting a significant strain interaction effect. A simulation predicts these interactions can cause the success of ARGs to depend on available host strains, and, to a lesser extent, can cause host strain success to depend on the ARGs present in a community. These results indicate the importance of considering ARG effects across different host strains, and especially the potential of refuge strains to allow resistance to persist in the absence of direct selection, in efforts to understand resistance dynamics.202438889784
4075180.9998Antimicrobial resistance in foodborne pathogens--a cause for concern? The widespread use of antibiotics in food animal production systems has resulted in the emergence of antibiotic resistant zoonotic bacteria that can be transmitted to humans through the food chain. Infection with antibiotic resistant bacteria negatively impacts on public health, due to an increased incidence of treatment failure and severity of disease. Development of resistant bacteria in food animals can result from chromosomal mutations but is more commonly associated with the horizontal transfer of resistance determinants borne on mobile genetic elements. Food may represent a dynamic environment for the continuing transfer of antibiotic resistance determinants between bacteria. Current food preservation systems that use a combination of environmental stresses to reduce growth of bacteria, may serve to escalate development and dissemination of antibiotic resistance among food related pathogens. The increasing reliance on biocides for pathogen control in food production and processing, heightens the risk of selection of biocide-resistant strains. Of particular concern is the potential for sublethal exposure to biocides to select for bacteria with enhanced multi-drug efflux pump activity capable of providing both resistance to biocides and cross-resistance to multiple antibiotics. Although present evidence suggests that biocide resistance is associated with a physiological cost, the possibility of the development of adaptive mutations conferring increased fitness cannot be ruled-out. Strategies aimed at inhibiting efflux pumps and eliminating plasmids could help to restore therapeutic efficacy to antibiotics and reduce the spread of antibiotic resistant foodborne pathogens through the food chain.200818781926
4124190.9998A risk analysis framework for the long-term management of antibiotic resistance in food-producing animals. In recent years, there has been increasing concern that the use of antibiotics in food-producing animals, particularly their long-term use for growth promotion, contributes to the emergence of antibiotic-resistant bacteria in animals. These resistant bacteria may spread from animals to humans via the food chain. They may also transfer their antibiotic-resistance genes into human pathogenic bacteria, leading to failure of antibiotic treatment for some, possibly life-threatening, human conditions. To assist regulatory decision making, the actual risk to human health from antibiotic use in animals needs to be determined (risk assessment) and the requirements for risk minimisation (risk management and risk communication) determined. We propose a novel method of risk analysis involving risk assessment for three interrelated hazards: the antibiotic (chemical agent), the antibiotic-resistant bacterium (microbiological agent) and the antibiotic-resistance gene (genetic agent). Risk minimisation may then include control of antibiotic use and/or the reduction of the spread of bacterial infection and/or prevention of transfer of resistance determinants between bacterial populations.200212385693