Insights into the impact of manure on the environmental antibiotic residues and resistance pool. - Related Documents




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743501.0000Insights into the impact of manure on the environmental antibiotic residues and resistance pool. The intensive use of antibiotics in the veterinary sector, linked to the application of manure-derived amendments in agriculture, translates into increased environmental levels of chemical residues, AR bacteria (ARB) and antibiotic resistance genes (ARG). The aim of this review was to evaluate the current evidence regarding the impact of animal farming and manure application on the antibiotic resistance pool in the environment. Several studies reported correlations between the prevalence of clinically relevant ARB and the amount and classes of antibiotics used in animal farming (high resistance rates being reported for medically important antibiotics such as penicillins, tetracyclines, sulfonamides and fluoroquinolones). However, the results are difficult to compare, due to the diversity of the used antimicrobials quantification techniques and to the different amounts and types of antibiotics, exhibiting various degradation times, given in animal feed in different countries. The soils fertilized with manure-derived products harbor a higher and chronic abundance of ARB, multiple ARG and an enriched associated mobilome, which is also sometimes seen in the crops grown on the amended soils. Different manure processing techniques have various efficiencies in the removal of antibiotic residues, ARB and ARGs, but there is only a small amount of data from commercial farms. The efficiency of sludge anaerobic digestion appears to be dependent on the microbial communities composition, the ARB/ARG and operating temperature (mesophilic vs. thermophilic conditions). Composting seems to reduce or eliminate most of antibiotics residues, enteric bacteria, ARB and different representative ARG in manure more rapidly and effectively than lagoon storage. Our review highlights that despite the body of research accumulated in the last years, there are still important knowledge gaps regarding the contribution of manure to the AMR emergence, accumulation, spread and risk of human exposure in countries with high clinical resistance rates. Land microbiome before and after manure application, efficiency of different manure treatment techniques in decreasing the AMR levels in the natural environments and along the food chain must be investigated in depth, covering different geographical regions and countries and using harmonized methodologies. The support of stakeholders is required for the development of specific best practices for prudent - cautious use of antibiotics on farm animals. The use of human reserve antibiotics in veterinary medicine and of unprescribed animal antimicrobials should be stopped and the use of antibiotics on farms must be limited. This integrated approach is needed to determine the optimal conditions for the removal of antibiotic residues, ARB and ARG, to formulate specific recommendations for livestock manure treatment, storage and handling procedures and to translate them into practical on-farm management decisions, to ultimately prevent exposure of human population.202236187968
743310.9999Manure as a Potential Hotspot for Antibiotic Resistance Dissemination by Horizontal Gene Transfer Events. The increasing demand for animal-derived foods has led to intensive and large-scale livestock production with the consequent formation of large amounts of manure. Livestock manure is widely used in agricultural practices as soil fertilizer worldwide. However, several antibiotic residues, antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria are frequently detected in manure and manure-amended soils. This review explores the role of manure in the persistence and dissemination of ARGs in the environment, analyzes the procedures used to decrease antimicrobial resistance in manure and the potential impact of manure application in public health. We highlight that manure shows unique features as a hotspot for antimicrobial gene dissemination by horizontal transfer events: richness in nutrients, a high abundance and diversity of bacteria populations and antibiotic residues that may exert a selective pressure on bacteria and trigger gene mobilization; reduction methodologies are able to reduce the concentrations of some, but not all, antimicrobials and microorganisms. Conjugation events are often seen in the manure environment, even after composting. Antibiotic resistance is considered a growing threat to human, animal and environmental health. Therefore, it is crucial to reduce the amount of antimicrobials and the load of antimicrobial resistant bacteria that end up in soil.202032823495
743420.9999Pig manure treatment strategies for mitigating the spread of antibiotic resistance. Due to the risk of pathogenic antibiotic-resistant bacteria and their antibiotic-resistance genes transfer from livestock feces to the soil and cultivated crops, it is imperative to find effective on-farm manure treatments to minimize that hazardous potential. An introduced worldwide policy of sustainable development, focus on ecological agricultural production, and the circular economy aimed at reducing the use of artificial fertilizers; therefore, such treatment methods should also maximize the fertilization value of animal manure. The two strategies for processing pig manure are proposed in this study-storage and composting. The present study examines the changes in the physicochemical properties of treated manure, in the microbiome, and in the resistome, compared to raw manure. This is the first such comprehensive analysis performed on the same batch of manure. Our results suggest that while none of the processes eliminates the environmental risk, composting results in a faster and more pronounced reduction of mobile genetic elements harboring antibiotic resistance genes, including those responsible for multi-drug resistance. Overall, the composting process can be an efficient strategy for mitigating the spread of antibiotic resistance in the environment and reducing the risk of its transfer to crops and the food chain while providing essential fertilizer ingredients.202337491438
743130.9999Antibiotic Resistant Bacteria in Municipal Wastes: Is There Reason for Concern? Recently, there has been increased concern about the presence of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG), in treated domestic wastewaters, animal manures and municipal biosolids. The concern is whether these additional sources of ARB contribute to antibiotic resistance levels in the environment, that is, "environmental antibiotic resistance." ARB and ARG occur naturally in soil and water, and it remains unclear whether the introduction of ARB in liquid and solid municipal and animal wastes via land application have any significant impact on the background levels of antibiotic resistance in the environment, and whether they affect human exposure to ARB. In this current review, we examine and re-evaluate the incidence of ARB and ARG resulting from land application activities, and offer a new perspective on the threat of antibiotic resistance to public health via exposure from nonclinical environmental sources. Based on inputs of ARBs and ARGs from land application, their fate in soil due to soil microbial ecology principles, and background indigenous levels of ARBs and ARGs already present in soil, we conclude that while antibiotic resistance levels in soil are increased temporally by land application of wastes, their persistence is not guaranteed and is in fact variable, and often contradictory based on application site. Furthermore, the application of wastes may not produce the most direct impact of ARGs and ARB on public health. Further investigation is still warranted in agriculture and public health, including continued scrutiny of antibiotic use in both sectors.201829505255
745440.9999Invited review: Fate of antibiotic residues, antibiotic-resistant bacteria, and antibiotic resistance genes in US dairy manure management systems. United States dairy operations use antibiotics (primarily β-lactams and tetracyclines) to manage bacterial diseases in dairy cattle. Antibiotic residues, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARG) can be found in dairy manure and may contribute to the spread of antibiotic resistance (AR). Although β-lactam residues are rarely detected in dairy manure, tetracycline residues are common and perhaps persistent. Generally, <15% of bacterial pathogen dairy manure isolates are ARB, although resistance to some antibiotics (e.g., tetracycline) can be higher. Based on available data, the prevalence of medically important ARB on dairy operations is generally static or may be declining for antibiotic-resistant Staphylococcus spp. Over 60 ARG can be found in dairy manure (including β-lactam and tetracycline resistance genes), although correlations with antibiotic usage, residues, and ARB have been inconsistent, possibly because of sampling and analytical limitations. Manure treatment systems have not been specifically designed to mitigate AR, though certain treatments have some capacity to do so. Generally, well-managed aerobic compost treatments reaching higher peak temperatures (>60°C) are more effective at mitigating antibiotic residues than static stockpiles, although this depends on the antibiotic residue and their interactions. Similarly, thermophilic anaerobic digesters operating under steady-state conditions may be more effective at mitigating antibiotic residues than mesophilic or irregularly operated digesters or anaerobic lagoons. The number of ARB may decline during composting and digestion or be enriched as the bacterial communities in these systems shift, affecting relative ARG abundance or acquire ARG during treatment. Antibiotic resistance genes often persist through these systems, although optimal management and higher operating temperature may facilitate their mitigation. Less is known about other manure treatments, although separation technologies may be unique in their ability to partition antibiotic residues based on sorption and solubility properties. Needed areas of study include determining natural levels of AR in dairy systems, standardizing and optimizing analytical techniques, and more studies of operating on-farm systems, so that treatment system performance and actual human health risks associated with levels of antibiotic residues, ARB, and ARG found in dairy manure can be accurately assessed.202031837779
647750.9999Antibiotics and Antibiotic Resistance Genes in Animal Manure - Consequences of Its Application in Agriculture. Antibiotic resistance genes (ARGs) are a relatively new type of pollutant. The rise in antibiotic resistance observed recently is closely correlated with the uncontrolled and widespread use of antibiotics in agriculture and the treatment of humans and animals. Resistant bacteria have been identified in soil, animal feces, animal housing (e.g., pens, barns, or pastures), the areas around farms, manure storage facilities, and the guts of farm animals. The selection pressure caused by the irrational use of antibiotics in animal production sectors not only promotes the survival of existing antibiotic-resistant bacteria but also the development of new resistant forms. One of the most critical hot-spots related to the development and dissemination of ARGs is livestock and poultry production. Manure is widely used as a fertilizer thanks to its rich nutrient and organic matter content. However, research indicates that its application may pose a severe threat to human and animal health by facilitating the dissemination of ARGs to arable soil and edible crops. This review examines the pathogens, potentially pathogenic microorganisms and ARGs which may be found in animal manure, and evaluates their effect on human health through their exposure to soil and plant resistomes. It takes a broader view than previous studies of this topic, discussing recent data on antibiotic use in farm animals and the effect of these practices on the composition of animal manure; it also examines how fertilization with animal manure may alter soil and crop microbiomes, and proposes the drivers of such changes and their consequences for human health.202133854486
739260.9999Distribution of genetic elements associated with antibiotic resistance in treated and untreated animal husbandry waste and wastewater. Animal breeding for meat production based on swine, cattle, poultry, and aquaculture is an activity that generates several impacts on the environment, among them the spread of antibiotic resistance. There is a worldwide concern related to the massive use of antibiotics, which causes selective pressure on the microbial community, triggering bacteria that contain "antibiotic resistance genes." According to the survey here presented, antibiotic resistance-related genes such as tetracyclines (tet), erythromycin (erm), and sulfonamides (sul), as well as the genetic mobile element interferon (int), are the most reported genetic elements in qualitative and quantitative studies of swine, cattle, poultry, and aquaculture manure/wastewater. It has been observed that biological treatments based on waste composting and anaerobic digestion are effective in ARG removal, particularly for tet, bla, erm, and qnr (quinolone) genes. On the other hand, sul and intI genes were more persistent in such treatments. Tertiary treatments, such advanced oxidative processes, are suitable strategies to improve ARG reduction. In general temperature, hydraulic retention time, and penetration of sunlight are the main operational parameters for ARG reduction in treatments applied to animal waste, and therefore attention should be addressed to optimize their efficacy regarding ARG removal. Despite being reduced, the presence of ARG in treated effluents and in biosolids indicates that there is a potential risk of antibiotic resistance spread in nature, especially through the release of treated livestock waste into the environment.202133835340
743270.9999Exploring the Animal Waste Resistome: The Spread of Antimicrobial Resistance Genes Through the Use of Livestock Manure. Antibiotic resistance is a public health problem of growing concern. Animal manure application to soil is considered to be a main cause of the propagation and dissemination of antibiotic residues, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) in the soil-water system. In recent decades, studies on the impact of antibiotic-contaminated manure on soil microbiomes have increased exponentially, in particular for taxonomical diversity and ARGs' diffusion. Antibiotic resistance genes are often located on mobile genetic elements (MGEs). Horizontal transfer of MGEs toward a broad range of bacteria (pathogens and human commensals included) has been identified as the main cause for their persistence and dissemination. Chemical and bio-sanitizing treatments reduce the antibiotic load and ARB. Nevertheless, effects of these treatments on the persistence of resistance genes must be carefully considered. This review analyzed the most recent research on antibiotic and ARG environmental dissemination conveyed by livestock waste. Strategies to control ARG dissemination and antibiotic persistence were reviewed with the aim to identify methods for monitoring DNA transferability and environmental conditions promoting such diffusion.202032793126
640280.9999Livestock and poultry breeding farms as a fixed and underestimated source of antibiotic resistance genes. The excessive use of antibiotics, disinfectants, and drugs in livestock and poultry breeding has resulted in a rise in the presence of antibiotic resistance genes (ARGs). Antibiotic-resistant bacteria (ARB) and ARGs have been widely found in animal feces, farm wastewater, and farm air. ARGs can not only spread across media through adsorption and migration, but also transfer resistance across bacterial genera through horizontal gene transfer. Livestock breeding has become a fixed and unavoidable source of ARGs in the environment. Existing technologies for controlling ARGs, such as composting, disinfection, and sewage treatment, are not efficient in removing ARB and ARGs from waste. Furthermore, the remaining ARGs still possess a strong capacity for dissemination. At present, antibiotics used in animal husbandry are difficult to replace in a short period of time. The growth and potential risks of resistance genes in livestock and poultry breeding sources in the receiving environment are not yet clear. In this paper, we summarize the current situation of ARGs in the livestock and poultry breeding environment. We also explain the key environmental processes, main influencing factors, and corresponding ecological risks associated with ARGs in this environment. The advantages and disadvantages of current technologies for the removal of ARGs are primarily discussed. There is a particular emphasis on clarifying the spatiotemporal evolution patterns and environmental process mechanisms of ARGs, as well as highlighting the importance and urgency of developing efficient pollution control technologies.202439052112
655490.9999Environmental and Public Health Implications of Water Reuse: Antibiotics, Antibiotic Resistant Bacteria, and Antibiotic Resistance Genes. Water scarcity is a global problem, and is particularly acute in certain regions like Africa, the Middle East, as well as the western states of America. A breakdown on water usage revealed that 70% of freshwater supplies are used for agricultural irrigation. The use of reclaimed water as an alternative water source for agricultural irrigation would greatly alleviate the demand on freshwater sources. This paradigm shift is gaining momentum in several water scarce countries like Saudi Arabia. However, microbial problems associated with reclaimed water may hinder the use of reclaimed water for agricultural irrigation. Of particular concern is that the occurrence of antibiotic residues in the reclaimed water can select for antibiotic resistance genes among the microbial community. Antibiotic resistance genes can be associated with mobile genetic elements, which in turn allow a promiscuous transfer of resistance traits from one bacterium to another. Together with the pathogens that are present in the reclaimed water, antibiotic resistant bacteria can potentially exchange mobile genetic elements to create the "perfect microbial storm". Given the significance of this issue, a deeper understanding of the occurrence of antibiotics in reclaimed water, and their potential influence on the selection of resistant microorganisms would be essential. In this review paper, we collated literature over the past two decades to determine the occurrence of antibiotics in municipal wastewater and livestock manure. We then discuss how these antibiotic resistant bacteria may impose a potential microbial risk to the environment and public health, and the knowledge gaps that would have to be addressed in future studies. Overall, the collation of the literature in wastewater treatment and agriculture serves to frame and identify potential concerns with respect to antibiotics, antibiotic resistant bacteria, and antibiotic resistance genes in reclaimed water.201327029309
7426100.9999Detection and fate of antibiotic resistant bacteria in wastewater treatment plants: a review. Antibiotics are among the most successful group of pharmaceuticals used for human and veterinary therapy. However, large amounts of antibiotics are released into municipal wastewater due to incomplete metabolism in humans or due to disposal of unused antibiotics, which finally find their ways into different natural environmental compartments. The emergence and rapid spread of antibiotic resistant bacteria (ARB) has led to an increasing concern about the potential environmental and public health risks. ARB and antibiotic resistant genes (ARGs) have been detected extensively in wastewater samples. Available data show significantly higher proportion of antibiotic resistant bacteria contained in raw and treated wastewater relative to surface water. According to these studies, the conditions in wastewater treatment plants (WWTPs) are favourable for the proliferation of ARB. Moreover, another concern with regards to the presence of ARB and ARGs is their effective removal from sewage. This review gives an overview of the available data on the occurrence of ARB and ARGs and their fate in WWTPs, on the biological methods dealing with the detection of bacterial populations and their resistance genes, and highlights areas in need for further research studies.201323414720
6977110.9999Tracking virulence genes and their interaction with antibiotic resistome during manure fertilization. Antibiotic resistance genes, collectively termed as antibiotic resistome, are regarded as emerging contaminants. Antibiotics resistome can be highly variable in different environments, imposing environmental safety concern and public health risk when it is in conjunction with pathogenic bacteria. However, it remains elusive how pathogenic bacteria interact with antibiotic resistome, making it challenging to assess microbial risk. Here, we examined the presence and relative abundance of bacterial virulence genes representing potential pathogens in swine manure, compost, compost-amended soil, and unamended agricultural soil in five suburban areas of Beijing, China. The absolute abundances of virulence genes were marginally significantly (p < 0.100) increased in compost-amended soils than unamended soil, revealing potential health risks in manure fertilization. The composition of potential pathogens differed by sample types and was linked to temperature, antibiotics, and heavy metals. As antibiotics can confer pathogens the resistance to clinic treatment, it was alarming to note that virulence genes tended to co-exist with antibiotic resistance genes, as shown by prevalently positive links among them. Collectively, our results demonstrate that manure fertilization in agriculture might give rise to the development of potentially antibiotic-resistant pathogens, unveiling an environmental health risk that has been frequently overlooked.202235810986
6478120.9999Antibiotic resistance in grass and soil. Antibiotic resistance is currently one of the greatest threats to human health. The global overuse of antibiotics in human medicine and in agriculture has resulted in the proliferation and dissemination of a multitude of antibiotic resistance genes (ARGs). Despite a large proportion of antibiotics being used in agriculture, little is understood about how this may contribute to the overall antibiotic resistance crisis. The use of manure in agriculture is a traditional and widespread practice and is essential for returning nutrients to the soil; however, the impact of continuous manure application on the environmental microbiome and resistome is unknown. The use of antibiotics in animal husbandry in therapeutic and sub-therapeutic doses creates a selective pressure for ARGs in the gut microbiome of the animal, which is then excreted in the faeces. Therefore, the application of manure to agricultural land is a potential route for the transmission of antibiotic-resistant bacteria from livestock to crops, animals and humans. It is of vital importance to understand the mechanisms behind ARG enrichment and its maintenance both on the plant and within the soil microbiome to mitigate the spread of this resistance to animals and humans. Understanding this link between human health, animal health, plant health and the environment is crucial to inform implementation of new regulations and practice regarding antibiotic use in agriculture and manure application, aimed at ensuring the antibiotic resistance crisis is not aggravated.201930783015
7388130.9999Poultry manure-derived microorganisms as a reservoir and source of antibiotic resistance genes transferred to soil autochthonous microorganisms. Animal husbandry is increasing yearly due to the growing demand for meat and livestock products, among other reasons. To meet these demands, prophylactic antibiotics are used in the livestock industry (i.e., poultry farming) to promote health and stimulate animal growth. However, antibiotics are not fully metabolized by animals, and they are evacuated to the environment with excreta. Animal manure is used as fertilizer to reduce the volume of waste generated in the livestock sector. However, manure often contains microorganisms harboring antibiotic resistance genes (ARGs). Then, the microbiome of manure applicate to the soil may contribute to the spread of antibiotic resistance in the environment, including autochthonous soil-dwelling microorganisms. The present study was conducted during the crops growing season in Poland (May to September 2019) to determine the influence of poultry manure as well as poultry manure supplemented with selected antibiotics on the diversity of the soil microbiome in treatments that had not been previously fertilized with manure and the ability of antibiotic-resistant bacteria to transfer ARGs to other soil bacteria. Antibiotic concentrations were elevated at the beginning of the study and decreased over time. Poultry manure induced significant changes in the structure of microbial communities in soil; the diversity of the soil microbiome decreased, and the abundance of bacterial genera Bradyrhizobium, Streptomyces, and Pseudomonas, which are characteristic of the analyzed manure, increased. Over time, soil microbial diversity was restored to the state observed before the application of manure. Genes conferring resistance to multiple drugs as well as genes encoding resistance to bacitracin and aminoglycosides were the most frequently identified ARGs in the analyzed bacteria, including on mobile genetic elements. Multidrug resistance was observed in 17 bacterial taxa, whereas ARGs were identified in 32 bacterial taxa identified in the soil microbiome. The results of the study conclude that the application of poultry manure supplemented with antibiotics initially affects soil microbiome and resistome diversity but finally, the soil shows resilience and returns to its original state after time, with most antibiotic resistance genes disappearing. This phenomenon is of great importance in sustainable soil health after manure application.202337832303
6481140.9999Fate and effects of veterinary antibiotics in soil. Large amounts of veterinary antibiotics are applied worldwide to farm animals and reach agricultural fields by manure fertilization, where they might lead to an increased abundance and transferability of antibiotic-resistance determinants. In this review we discuss recent advances, limitations, and research needs in determining the fate of veterinary antibiotics and resistant bacteria applied with manure to soil, and their effects on the structure and function of soil microbial communities in bulk soils and the rhizosphere. The increased abundance and mobilization of antibiotic-resistance genes (ARGs) might contribute to the emergence of multi-resistant human pathogens that increasingly threaten the successful antibiotic treatment of bacterial infections.201424950802
7453150.9999Long-term application of Swedish sewage sludge on farmland does not cause clear changes in the soil bacterial resistome. The widespread practice of applying sewage sludge to arable land makes use of nutrients indispensable for crops and reduces the need for inorganic fertilizer, however this application also provides a potential route for human exposure to chemical contaminants and microbial pathogens in the sludge. A recent concern is that such practice could promote environmental selection and dissemination of antibiotic resistant bacteria or resistance genes. Understanding the risks of sludge amendment in relation to antibiotic resistance development is important for sustainable agriculture, waste treatment and infectious disease management. To assess such risks, we took advantage of an agricultural field trial in southern Sweden, where land used for growing different crops has been amended with sludge every four years since 1981. We sampled raw, semi-digested and digested and stored sludge together with soils from the experimental plots before and two weeks after the most recent amendment in 2017. Levels of selected antimicrobials and bioavailable metals were determined and microbial effects were evaluated using both culture-independent metagenome sequencing and conventional culturing. Antimicrobials or bioavailable metals (Cu and Zn) did not accumulate to levels of concern for environmental selection of antibiotic resistance, and no coherent signs, neither on short or long time scales, of enrichment of antibiotic-resistant bacteria or resistance genes were found in soils amended with digested and stored sewage sludge in doses up to 12 metric tons per hectare. Likewise, only very few and slight differences in microbial community composition were observed after sludge amendment. Taken together, the current study does not indicate risks of sludge amendment related to antibiotic resistance development under the given conditions. Extrapolations should however be done with care as sludge quality and application practices vary between regions. Hence, the antibiotic concentrations and resistance load of the sludge are likely to be higher in regions with larger antibiotic consumption and resistance burden than Sweden.202032036119
6512160.9999Antimicrobial Resistance in the Environment. This review summarizes selected publications of 2016 with emphasis on occurrence and treatment of antibiotic resistance genes and bacteria in the aquatic environment and wastewater and drinking water treatment plants. The review is conducted with emphasis on fate, modeling, risk assessment and data analysis methodologies for characterizing abundance. After providing a brief introduction, the review is divided into the following four sections: i) Occurrence of AMR in the Environment, ii) Treatment Technologies for AMR, iii) Modeling of Fate, Risk, and Environmental Impact of AMR, and iv) ARG Databases and Pipelines.201728954648
7385170.9999Soil-specific responses in the antibiotic resistome of culturable Acinetobacter spp. and other non-fermentative Gram-negative bacteria following experimental manure application. Acinetobacter spp. and other non-fermenting Gram-negative bacteria (NFGNB) represent an important group of opportunistic pathogens due to their propensity for multiple, intrinsic, or acquired antimicrobial resistance (AMR). Antimicrobial resistant bacteria and their genes can spread to the environment through livestock manure. This study investigated the effects of fresh manure from dairy cows under antibiotic prophylaxis on the antibiotic resistome and AMR hosts in microcosms using pasture soil. We specifically focused on culturable Acinetobacter spp. and other NFGNB using CHROMagar Acinetobacter. We conducted two 28-days incubation experiments to simulate natural deposition of fresh manure on pasture soil and evaluated the effects on antibiotic resistance genes (ARGs) and bacterial hosts through shotgun metagenomics. We found that manure application altered the abundance and composition of ARGs and their bacterial hosts, and that the effects depended on the soil source. Manure enriched the antibiotic resistome of bacteria only in the soil where native bacteria had a low abundance of ARGs. Our study highlights the role of native soil bacteria in modulating the consequences of manure deposition on soil and confirms the potential of culturable Acinetobacter spp. and other NFGNB to accumulate AMR in pasture soil receiving fresh manure.202337977851
6487180.9998An evaluation of conventional and nature-based technologies for controlling antibiotic-resistant bacteria and antibiotic-resistant genes in wastewater treatment plants. Antibiotic resistance is a globally recognized health concern which leads to longer hospital stays, increased morbidity, increased mortality, and higher medical costs. Understanding how antibiotic resistance persists and exchanges in environmental systems like soil, water, and wastewater are critically important for understanding the emergence of pathogens with new resistance profiles and the subsequent exposure of people who indirectly/directly come in contact with these pathogens. There are concerns about the widespread application of prophylactic antibiotics in the clinical and agriculture sectors, as well as chemicals/detergents used in food and manufacturing industries, especially the quaternary ammonium compounds which have been found responsible for the generation of resistant genes in water and soil. The rates of horizontal gene transfer increase where there is a lack of proper water/wastewater infrastructure, high antibiotic manufacturing industries, or endpoint users - such as hospitals and intensive agriculture. Conventional wastewater treatment technologies are often inefficient in the reduction of ARB/ARGs and provide the perfect combination of conditions for the development of antibiotic resistance. The wastewater discharged from municipal facilities may therefore be enriched with bacterial communities/pathogens and provide a suitable environment (due to the presence of nutrients and other pollutants) to enhance the transfer of antibiotic resistance. However, facilities with tertiary treatment (either traditional/emerging technologies) provide higher rates of reduction. This review provides a synthesis of the current understanding of wastewater treatment and antibiotic resistance, examining the drivers that may accelerate their possible transmission to a different environment, and highlighting the need for tertiary technologies used in treatment plants for the reduction of resistant bacteria/genes.202438286289
7389190.9998Temporal changes of antibiotic-resistance genes and bacterial communities in two contrasting soils treated with cattle manure. The emerging environmental spread of antibiotic-resistance genes (ARGs) and their subsequent acquisition by clinically relevant microorganisms is a major threat to public health. Animal manure has been recognized as an important reservoir of ARGs; however, the dissemination of manure-derived ARGs and the impacts of manure application on the soil resistome remain obscure. Here, we conducted a microcosm study to assess the temporal succession of total bacteria and a broad spectrum of ARGs in two contrasting soils following manure application from cattle that had not been treated with antibiotics. High-capacity quantitative PCR detected 52 unique ARGs across all the samples, with β-lactamase as the most dominant ARG type. Several genes of soil indigenous bacteria conferring resistance to β-lactam, which could not be detected in manure, were found to be highly enriched in manure-treated soils, and the level of enrichment was maintained over the entire course of 140 days. The enriched β-lactam resistance genes had significantly positive relationships with the relative abundance of the integrase intI1 gene, suggesting an increasing mobility potential in manure-treated soils. The changes in ARG patterns were accompanied by a significant effect of cattle manure on the total bacterial community compositions. Our study indicates that even in the absence of selective pressure imposed by agricultural use of antibiotics, manure application could still strongly impact the abundance, diversity and mobility potential of a broad spectrum of soil ARGs. Our findings are important for reliable prediction of ARG behaviors in soil environment and development of appropriate strategies to minimize their dissemination.201626712351