Combating Antimicrobial Resistance A One Health Approach to a Global Threat: Proceedings of a Workshop (2017) / Chapter Skim
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3 Microbial and Genetic Movements Across the One Health Domains
3 Microbial and Genetic Movements Across the One Health Domains
Pages 13-38
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From page 13... ...
James Tiedje, university distinguished professor of microbiology and molecular genetics and of plant, soil, and microbial sciences at Michigan State University, discussed environmental surveillance for antimicrobial resistance and identifying horizontal gene exchange as the point of control. The effect of antimicrobials in the environment was the focus of the session's second half, moderated by Jeffrey Silverstein, deputy administrator of animal production and protection with the U.S.
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From page 14... ...
At its outset, NARMS was tasked with integrated surveillance of antimicrobial resistance in foodborne bacteria, which he defined as the coordinated sampling and testing of bacteria from food animals, foods, and clinically ill humans and the subsequent evaluation of antimicrobial resistance trends throughout the food production and supply chain using harmonized methods. In the years since, he said, the concept of integrated surveillance has shifted to One Health surveillance, which includes an environmental component.
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From page 15... ...
Pre-harvest surveillance data support risk analysis of foodborne antimicrobial resistance hazards as part of the qualitative risk assessment process for preapproving new animal antibiotics. Post-harvest data contribute to identifying interventions to contain resistance and to evaluating the effectiveness of antibiotics after approval.1 Finally, he said that One Health surveillance data are used to evaluate 1 As examples, he cited FDA's withdrawal of fluoroquinolones for use in poultry and its prohibition of extra-label use of third-generation cephalosporins; the latter has had a measurable and fairly immediate effect in both human and animal isolates, he said.
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From page 16... ...
sole therapies or one of few alternatives to treat serious human disease, and (2) used to treat diseases caused by either organisms that may be transmitted to humans from nonhuman sources, or human diseases causes by organisms that may acquire resistance genes from nonhuman sources (WHO, 2012)
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From page 17... ...
SOURCE: McDermott presentation, June 20, 2017. supply in the United States, antibiotic resistance is roughly on par with the European Union.
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NARMS needs to incorporate programs for food animal and companion animal pathogen surveillance, he said, as well as for on-farm testing to assess husbandry practices on resistance. He said that an environmental surveillance piece is needed to complete the One Health platform and to better understand the movement of pathogens and resistance genes, both in the United States and worldwide.
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From page 19... ...
Sampling methodologies for antimicrobial susceptibility testing are not consistent within and between different countries, said Cray, so improving quality control and harmonizing culture-sampling methodologies will be crucial for better data integration. Current activities aimed at this goal include global- and national-level action plans led by WHO and its Advisory Group on Integrated Surveillance of Antimicrobial Resistance,5 by the Food and Agriculture Organization of the United Nations (FAO)
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From page 20... ...
Every gram of soil in the native resistome, which is a collection of all the antimicrobial resistance genes in a microbial environment, contains antibiotic resistance in its microbes, which can be steered in a problematic direction
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From page 21... ...
Resistance Clusters and Coselection Resistance clusters and coselection for antibiotics, heavy metals, and disinfectants are key parts of the resistance problem, said Tiedje. Evidence suggests strong correlations between certain antibiotic resistance genes and mobile genetic elements, he said.
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From page 22... ...
Environmental Science and Technology 49(11)
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From page 23... ...
(2016) have developed an antimicrobial resistance dashboard application designed to geospatially map antibiotic resistance genes and antibiotic-resistant bacteria from environments and clinics.
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From page 24... ...
ANTIMICROBIALS IN THE ENVIRONMENT Interface and Pathways of Gene Transfer Many current antibiotic-resistant infections are the result of very rare genetic events, said Price, so the overarching goal should be reducing the opportunity for these rare genetic events to occur, for example, in billions of food animals worldwide. He added that intervening effectively requires
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From page 25... ...
Resistance Transmission in Salmonella and Campylobacter Bacteria New multidrug resistance determinants in Salmonella have been associated with the introduction of antibiotics to animals, said Price. The reverse scenario, rapid decrease in resistance, has also been observed when antibiotics have been removed from food animal production.
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Next-generation DNA sequencing and other new tools are revealing more about coresistance and horizontal gene transfer in COPs, said Price. An example from the Netherlands illustrates how coresistance can fuel the spread of resistance in the absence of profligate antibiotic use.
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Bayesian molecular clock analyses can be used to estimate the point of time in prehistory when two or more life forms diverged; he suggested that it will also help to estimate the timing of when mobile elements jump BOX 3-2 A Critical Threat of Horizontal Gene Transfer An example of horizontal gene transfer comes from China, said Price. In 2016, a new mobile element -- mobilized colistin resistance (mcr-1)
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From page 28... ...
Pathogenic organisms can carry antibiotic resistance genes, he said, but commensal organisms can also carry antibiotic resistance genes that ultimately can be transmitted to pathogens. He presented Figure 3-4, which articulates the sources and transmission pathways of antimicrobial resistance within the One Health framework.
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From page 29... ...
Being able to identify the source of waterborne antimicrobial resistance is particularly critical in low-income countries without adequate infrastructure for potable water or wastewater treatment, Topp said. Some bacteria, such as Escherichia coli O157:H7 bovine, have reservoirs that are specific enough to trace if detected in water.
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From page 30... ...
Environmental Persistence of Antibiotic Resistance Genes Antibiotic resistance genes can persist for at least months in crop ground through commercial-scale application of animal manures, said Topp. Whether all antibiotic resistance genes in soil behave consistently with respect to their persistence in dynamics remains unknown, but evidence suggests that certain proxies or sentinel DNA markers may represent many antibiotic resistance genes, he said.
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From page 31... ...
We can measure, we can quantify antibiotic resistance genes or bacteria, but we really have very little understanding of the significance of that to human health in a risk assessment context. So we really need to make the leap from exposure to hazard to risk.
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From page 32... ...
While drug use is a strong driver of antibiotic resistance in the animal gut, she said, increasing evidence suggests the need to revisit that assumption and identify the factors -- other than drug use -- that drive the transfer of antimicrobialresistant drugs, bacteria, and genes out of the agricultural system. Manure Management Strategies Durso surveyed current management options for reducing resistance transfer in manure.
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From page 33... ...
use and disposal of medicine, BOX 3-3 Promising Manure Management Strategies Wood chip bioreactors and thermal processing are two promising strategies for mitigating antibiotic resistance, said Durso. In Iowa, a study on wood chip bio reactors in tile drain systems is using metagenomics to track antibiotic-resistant bacteria and antibiotic resistance genes from the point at which manure is applied to the land, through its transport in the soil, and onto its potential leeching into the tile drain water.
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From page 34... ...
, Brooks acknowledged that the phenomenon at hand may indeed be accelerated, and many stakeholders in the industry recognize the elevated levels of antimicrobials in environmental samples. The industry's supply chain for established antibiotics is complex and global, he said, stating that it has a significant footprint; it has also raised concerns of environmental pollution from some drug manufacturing companies in emerging markets such as China and India.
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From page 35... ...
To ensure the effectiveness of those controls, he indicated, research is needed to measure wastewater concentrations, to establish "safe" discharge concentrations, and to better understand the role of other coselective agents such as metals, biocides, and cleaning agents. Road Map to Reduce Environmental Impact of Antibiotic Production Leading companies and industry organizations have publicly committed to address the risk of antimicrobial resistance by releasing the Declaration on Antimicrobial Resistance at the World Economic Forum in Davos, Switzerland, in January 2016,13 with signatories including more than 80 biopharmaceutical companies.
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From page 36... ...
DISCUSSION Duchin asked if traditional toxicologists have been engaged to help address challenges in risk assessment. Durso replied that the toxicological framework is being widely adopted in the environmental realm, with antibiotic-resistant bacteria and antibiotic resistance genes classified as contaminants.
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From page 37... ...
Brooks predicted that a wider network of publicly owned wastewater treatment plants will be necessary, especially in large cities, to handle other nonmanufacturing sources of resistance, such as excreted metabolized antibiotics. Gerald Keusch, associate director of the National Emerging Infectious Diseases Laboratory at Boston University, added that clinicians rarely consider the excretion of a drug from a patient.
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