Origins and environmental mobility of antibiotic resistance genes, virulence factors and bacteria in a tidal creek's watershed. - Related Documents




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367301.0000Origins and environmental mobility of antibiotic resistance genes, virulence factors and bacteria in a tidal creek's watershed. AIMS: To compare bacterial compositions of watershed run-offs released by a human settlement and a forested area, and to evaluate their role as carriers of antibiotic resistance and virulence genes. METHODS AND RESULTS: Run-offs from a forested area and a small settlement in a tidal creek' s watershed were compared for bacterial composition and profiles of 16 tetracycline resistance (TRG), eight virulence (VG) and integrase1 and 2 genes. Integrase 1 gene was detected only once. No integrase 2 gene was observed. VGs were detected only in settlement's run-offs, and TRG incidence frequency there was twice as high as in the forest's run-offs. Gene incidences revealed a positive correspondence to the rainfall, and weak correlations to water parameters. Metagenomic, Principle Coordinates and Shannon analyses together revealed distinctive bacterial compositions of the forest's and settlement's run-offs. Passage of the latter through a salt marsh resulted in the elimination of TRGs and three-fold decrease in VG incidence, and their bacterial composition was shifted towards that of the tidal creek. CONCLUSIONS: The settlement was a major source of TRGs and VGs in the watershed, but these contaminants were mitigated by a salt marsh system. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data revealed the role of small settlements in biological contamination of the coastal waters. They also indicated that salt marshes are capable of reducing not only chemical but also biological contamination of run-offs.201525556404
740710.9999Impact of salmon farming in the antibiotic resistance and structure of marine bacterial communities from surface seawater of a northern Patagonian area of Chile. BACKGROUND: Aquaculture and salmon farming can cause environmental problems due to the pollution of the surrounding waters with nutrients, solid wastes and chemicals, such as antibiotics, which are used for disease control in the aquaculture facilities. Increasing antibiotic resistance in human-impacted environments, such as coastal waters with aquaculture activity, is linked to the widespread use of antibiotics, even at sub-lethal concentrations. In Chile, the world's second largest producer of salmon, aquaculture is considered the primary source of antibiotics residues in the coastal waters of northern Patagonia. Here, we evaluated whether the structure and diversity of marine bacterial community, the richness of antibiotic resistance bacteria and the frequency of antibiotic resistance genes increase in communities from the surface seawater of an area with salmon farming activities, in comparison with communities from an area without major anthropogenic disturbance. RESULTS: The taxonomic structure of bacterial community was significantly different between areas with and without aquaculture production. Growth of the culturable fraction under controlled laboratory conditions showed that, in comparison with the undisturbed area, the bacterial community from salmon farms displayed a higher frequency of colonies resistant to the antibiotics used by the salmon industry. A higher adaptation to antibiotics was revealed by a greater proportion of multi-resistant bacteria isolated from the surface seawater of the salmon farming area. Furthermore, metagenomics data revealed a significant higher abundance of antibiotic resistant genes conferring resistance to 11 antibiotic families in the community from salmon farms, indicating that the proportion of bacteria carrying the resistance determinants was overall higher in salmon farms than in the undisturbed site. CONCLUSIONS: Our results revealed an association between bacterial communities and antibiotic resistance from surface seawater of a coastal area of Chile. Although the total bacterial community may appear comparable between sites, the cultivation technique allowed to expose a higher prevalence of antibiotic resistant bacteria in the salmon farming area. Moreover, we demonstrated that metagenomics (culture-independent) and phenotypic (culture-dependent) methods are complementary to evaluate the bacterial communities' risk for antibiotic resistance, and that a human-influenced environment (such as salmon farms) can potentiate bacteria to adapt to environmental stresses, such as antibiotics.202439523335
368320.9998Small and large-scale distribution of four classes of antibiotics in sediment: association with metals and antibiotic resistance genes. Antibiotic chemicals and antibiotic resistance genes enter the environment via wastewater effluents as well as from runoff from agricultural operations. The relative importance of these two sources, however, is largely unknown. The relationship between the concentrations of chemicals and genes requires exploration, for antibiotics in the environment may lead to development or retention of resistance genes by bacteria. The genes that confer resistance to metal toxicity may also be important in antibiotic resistance. In this work, concentrations of 19 antibiotics (using liquid chromatography tandem mass spectrometry), 14 metals (using inductively coupled plasma-mass spectrometry), and 45 metal, antibiotic, and antibiotic-resistance associated genes (using a multiplex, microfluidic quantitative polymerase chain reaction method) were measured in 13 sediment samples from two large rivers as well as along a spatial transect in a wastewater effluent-impacted lake. Nine of the antibiotics were detected in the rivers and 13 were detected in the lake. Sixteen different resistance genes were detected. The surrounding land use and proximity to wastewater treatment plants are important factors in the number and concentrations of antibiotics detected. Correlations among antibiotic chemical concentrations, metal concentrations, and resistance genes occur over short spatial scales in a lake but not over longer distances in major rivers. The observed correlations likely result from the chemicals and resistance genes arising from the same source, and differences in fate and transport over larger scales lead to loss of this relationship.201830043816
731430.9998Microbial diversity and antibiotic resistance in a final effluent-receiving lake. Wastewater treatment plants have been recognised as hotspots for antibiotic resistance genes and antibiotic-resistant bacteria which enter the environment. However, the persistence of these genes and bacteria in receiving ecosystems remains poorly understood. The aim of the study was to evaluate the effect of final effluent release on microbial diversity and the antibiotic resistance gene pool in a final effluent-receiving lake. The numbers of total culturable heterotrophs and unculturable bacteria (represented as the 16S rRNA gene copy number) were significantly reduced during the treatment process. The number of ampicillin-resistant bacteria was higher in the sediment than in water samples, suggesting accumulation of ampicillin-resistant bacteria in freshwater sediments. Using an exogenous method, we captured 56 resistance plasmids which were further characterised. Next-generation sequencing revealed that the microbial phyla represented in the studied metagenomes were typical of corresponding environments. The highest relative abundance of antibiotic resistance genes was observed in the final effluent, suggesting that a considerable number of genes were released from the wastewater treatment plant. However, the lowest relative abundance and lowest diversity of the genes in the lake water, compared to the other studied metagenomes, suggest a negligible effect of treated sewage release on antibiotic resistance within water microbial communities of the lake. Furthermore, uncontrolled sewage dumping into this reservoir in the past as well as lower quality of the water upstream of the lake indicated that the wastewater treatment plant protected the studied ecosystem.201930373071
368040.9998Metagenomic Insights Into the Contribution of Phages to Antibiotic Resistance in Water Samples Related to Swine Feedlot Wastewater Treatment. In this study, we examined the types of antibiotic resistance genes (ARGs) possessed by bacteria and bacteriophages in swine feedlot wastewater before and after treatment using a metagenomics approach. We found that the relative abundance of ARGs in bacterial DNA in all water samples was significantly higher than that in phages DNA (>10.6-fold), and wastewater treatment did not significantly change the relative abundance of bacterial- or phage-associated ARGs. We further detected the distribution and diversity of the different types of ARGs according to the class of antibiotics to which they confer resistance, the tetracycline resistance genes were the most abundant resistance genes and phages were more likely to harbor ATP-binding cassette transporter family and ribosomal protection genes. Moreover, the colistin resistance gene mcr-1 was also detected in the phage population. When assessing the contribution of phages in spreading different groups of ARGs, β-lactamase resistance genes had a relatively high spreading ability even though the abundance was low. These findings possibly indicated that phages not only could serve as important reservoir of ARG but also carry particular ARGs in swine feedlot wastewater, and this phenomenon is independent of the environment.201830459724
739650.9998Antibiotic resistant bacteria and resistance genes in the bottom sediment of a small stream and the potential impact of remobilization. River sediments are regarded as hot spots of bacterial density and activity. Moreover, high bacterial densities and biofilm formation are known to promote horizontal gene transfer, the latter playing a vital role in the spread of antimicrobial resistance. It can thus be hypothesized that sediments act as a reservoir of antibiotic resistant bacteria (ARB) and resistance genes (ARGs), particularly in rivers receiving microbes and drug residues from treated sewage. We analyzed the phenotypic susceptibility of 782 Escherichia coli isolates against 24 antimicrobials and we measured the relative abundances of five ARGs in water and sediment extracts of a small stream. We did not find evidence for a general increase in the proportion of resistant E. coli isolated from sediments as compared to those found in stream water. For most antimicrobials, the likelihood of detecting a resistant isolate was similar in water and sediment or it was even lower in the latter compartment. The mean relative abundance of ARGs was moderately increased in sediment-borne samples. Generally, absolute abundances of resistant cells and resistance genes in the sediment exceeded the pelagic level owing to higher bacterial densities. The river bottom thus represents a reservoir of ARB and ARGs that can be mobilized by resuspension.201829982428
323560.9998Vertical distribution of antibiotic resistance genes in an urban green facade. The phyllosphere is considered a key site for the transfer of both naturally and anthropogenically selected antimicrobial resistance genes (ARGs) to humans. Consequently, the development of green building systems may pose an, as yet, unexplored pathway for ARGs and pathogens to transfer from the environment to outdoor plants. We collected leaves from plants climbing up buildings at 1, 2, 4 and 15 m above ground level and collected associated dust samples from adjacent windowsills to determine the diversity and relative abundance of microbiota and ARGs. Overall, a total of 143 ARGs from 11 major classes and 18 mobile genetic elements (MGEs) were detected. The relative abundance of ARGs within the phyllosphere decreased with increasing height above ground level. Fast expectation-maximization microbial source tracking (FEAST) suggested that the contribution of soil and aerosols to the phyllosphere microbiome was limited. A culture-dependent method to isolate bacteria from plant tissues identified a total of 91 genera from root, stem, and leaf samples as well as endophytes isolated from leaves. Of those bacteria, 20 isolates representing 9 genera were known human pathogenic members to humans. Shared bacterial from culture-dependent and culture-independent methods suggest microorganisms may move from soil to plant, potentially through an endophytic mechanism and thus, there is a clear potential for movement of ARGs and human pathogens from the outdoor environment.202133721724
738170.9998Constitutive presence of antibiotic resistance genes within the bacterial community of a large subalpine lake. The fate of antibiotic resistance genes (ARGs) in environmental microbial communities is of primary concern as prodromal of a potential transfer to pathogenic bacteria. Although of diverse origin, the persistence of ARGs in aquatic environments is highly influenced by anthropic activities, allowing potential control actions in well-studied environments. However, knowledge of abundance and space-time distribution of ARGs in ecosystems is still scarce. Using quantitative real-time PCR, we investigated the presence and the abundance of twelve ARGs (against tetracyclines, β-lactams, aminoglycosides, quinolones and sulphonamides) at different sampling sites, depths and seasons, in Lake Maggiore, a large subalpine lake, and in the area of its watershed. We then evaluated the correlation between each ARG and a number of ecological parameters in the water column in the deepest part of the lake. Our results suggest the constitutive presence of at least four ARGs within the bacterial community with a high proportion of bacteria potentially resistant to tetracyclines and sulphonamides. The presence of these ARGs was independent of the total bacterial density and temperature. The dynamics of tet(A) and sulII genes were, however, positively correlated with dissolved oxygen and negatively to chlorophyll a, suggesting that the resistant microbes inhabit specific niches. These observations indicate that the lake is a reservoir of antibiotic resistances, highlighting the need of a deeper understanding of the sources of ARGs and the factors allowing their persistence in waters.201526118321
740680.9998Relationship between antibiotic resistance genes and metals in residential soil samples from Western Australia. Increasing drug-resistant infections have drawn research interest towards examining environmental bacteria and the discovery that many factors, including elevated metal conditions, contribute to proliferation of antibiotic resistance (AR). This study examined 90 garden soils from Western Australia to evaluate predictions of antibiotic resistance genes from total metal conditions by comparing the concentrations of 12 metals and 13 genes related to tetracycline, beta-lactam and sulphonamide resistance. Relationships existed between metals and genes, but trends varied. All metals, except Se and Co, were related to at least one AR gene in terms of absolute gene numbers, but only Al, Mn and Pb were associated with a higher percentage of soil bacteria exhibiting resistance, which is a possible indicator of population selection. Correlations improved when multiple factors were considered simultaneously in a multiple linear regression model, suggesting the possibility of additive effects occurring. Soil-metal concentrations must be considered when determining risks of AR in the environment and the proliferation of resistance.201727822686
732490.9998Microbial and Viral Communities and Their Antibiotic Resistance Genes Throughout a Hospital Wastewater Treatment System. Antibiotic resistance poses a serious threat to global public health, and antibiotic resistance determinants can enter natural aquatic systems through discharge of wastewater effluents. Hospital wastewater in particular is expected to contain high abundances of antibiotic resistance genes (ARGs) compared to municipal wastewater because it contains human enteric bacteria that may include antibiotic-resistant organisms originating from hospital patients, and can also have high concentrations of antibiotics and antimicrobials relative to municipal wastewater. Viruses also play an important role in wastewater treatment systems since they can influence the bacterial community composition through killing bacteria, facilitating transduction of genetic material between organisms, and modifying the chromosomal content of bacteria as prophages. However, little is known about the fate and connections between ARGs, viruses, and their associated bacteria in hospital wastewater systems. To address this knowledge gap, we characterized the composition and persistence of ARGs, dsDNA viruses, and bacteria from influent to effluent in a pilot-scale hospital wastewater treatment system in Israel using shotgun metagenomics. Results showed that ARGs, including genes conferring resistance to antibiotics of high clinical relevance, were detected in all sampling locations throughout the pilot-scale system, with only 16% overall depletion of ARGs per genome equivalent between influent and effluent. The most common classes of ARGs detected throughout the system conferred resistance to aminoglycoside, cephalosporin, macrolide, penam, and tetracycline antibiotics. A greater proportion of total ARGs were associated with plasmid-associated genes in effluent compared to in influent. No strong associations between viral sequences and ARGs were identified in viral metagenomes from the system, suggesting that phage may not be a significant vector for ARG transfer in this system. The majority of viruses in the pilot-scale system belonged to the families Myoviridae, Podoviridae, and Siphoviridae. Gammaproteobacteria was the dominant class of bacteria harboring ARGs and the most common putative viral host in all samples, followed by Bacilli and Betaproteobacteria. In the total bacterial community, the dominant class was Betaproteobacteria for each sample. Overall, we found that a variety of different types of ARGs and viruses were persistent throughout this hospital wastewater treatment system, which can be released to the environment through effluent discharge.202032140141
7414100.9998Structure of the manure resistome and the associated mobilome for assessing the risk of antimicrobial resistance transmission to crops. In this study, the impact of bovine and poultry manure on the quantitative and qualitative composition of antibiotic resistance genes (ARGs) and the environmental mobilome associated with antimicrobial resistance in soil and crops was determined with the use of next generation sequencing methods. The aim of the study was to perform a metagenomic analysis of manure to estimate the risk of the transmission of ARGs and bacterial drug resistance carriers to fertilized soil and crops. The total copy number of ARGs was nearly four times higher in poultry manure (555 ppm) than in bovine manure (140 ppm), and this relationship was also noted in fertilized soil. Poultry manure induced a much greater increase in the concentrations of ARGs in the soil environment (196.4 ppm) than bovine manure (137.8 ppm) immediately after supplementation. The application of poultry manure led to the highest increase in the abundance of genes encoding resistance to tetracyclines (9%), aminoglycosides (3.5%), sulfonamides (3%), bacitracin (2%), chloramphenicol (2%), and macrolide-lincosamide-streptogramin antibiotics (1%). Heavy metals were stronger promoters of antibiotic resistance in the environment than antibiotics. Antibiotics exerted a greater influence on maintaining the diversity of ARGs than on increasing their abundance in soil. Large quantities of insertion sequences (IS), including those associated with the mobility of ARGs in the population of ESKAPEE pathogens, are introduced to soil with manure. These IS remain stable for up to several months, which indicates that manure, in particular poultry manure, significantly increases the risk of rapid ARG transfer to the environment. Manure also largely contributes to an increase in the diversity of the resistome and mobilome in the metagenome of bacteria isolated from crops. Bacteria of the phylum Proteobacteria appear to play a major role in the transmission of multiple ARGs in crops grown for human and animal consumption.202234864022
3679110.9998Aquaculture changes the profile of antibiotic resistance and mobile genetic element associated genes in Baltic Sea sediments. Antibiotics are commonly used in aquaculture and they can change the environmental resistome by increasing antibiotic resistance genes (ARGs). Sediment samples were collected from two fish farms located in the Northern Baltic Sea, Finland, and from a site outside the farms (control). The sediment resistome was assessed by using a highly parallel qPCR array containing 295 primer sets to detect ARGs, mobile genetic elements and the 16S rRNA gene. The fish farm resistomes were enriched in transposon and integron associated genes and in ARGs encoding resistance to antibiotics which had been used to treat fish at the farms. Aminoglycoside resistance genes were also enriched in the farm sediments despite the farms not having used aminoglycosides. In contrast, the total relative abundance values of ARGs were higher in the control sediment resistome and they were mainly genes encoding efflux pumps followed by beta-lactam resistance genes, which are found intrinsically in many bacteria. This suggests that there is a natural Baltic sediment resistome. The resistome associated with fish farms can be from native ARGs enriched by antibiotic use at the farms and/or from ARGs and mobile elements that have been introduced by fish farming.201626976842
7363120.9998Occurrence of antibiotics and antibiotic resistance genes at various stages of different aquaculture modes surrounding Tai Lake, China. INTRODUCTION: Aquaculture is an important source of antibiotics and ARGs in environmental waters. However, the occurrence of antibiotics and ARGs under different modes and stages of aquaculture has rarely been systematically studied. METHODS: This paper uses qPCR, LC-MS, and High-Throughput sequencing across different culture modes and stages to investigate antibiotics, resistance genes, and microbial communities in the water bodies, and analyze contamination differences between these modes. RESULTS: The quinolone and chloramphenicol were the main antibiotics, and the highest absolute abundance genes were quinolone resistance genes (qnrB) and quinolone resistance genes (sul1), with the mobile genetic element (MGE) intI1, both of which exhibited a gradual seasonal increase. Microbial diversity also varies seasonally, especially with a gradual increase in the abundance of some pathogenic bacteria (Flavobacterium). Antibiotics and resistance genes were found at higher levels in fish ponds compared to shrimp and crab ponds, while they were lower in shrimp and crab ponds that utilized the ecological mode ponds than in the traditional culture mode ponds. CONCLUSION: Our study presents a comprehensive characterization of antibiotics and ARGs in aquaculture waters from various perspectives. Ecological aquaculture modes contribute to reducing antibiotic and resistance gene pollution in water bodies. These findings will support the optimization of aquaculture mode and antibiotic usage to the green and sustainable development of aquaculture finally.202539959160
7114130.9998Antibiotic Resistance Genes in Freshwater Trout Farms in a Watershed in Chile. Point sources such as wastewater treatment plants, terrestrial agriculture, and aquaculture may release antibiotic residues, antibiotic resistant bacteria, and antibiotic resistance genes (ARGs) into aquatic ecosystems. However, there is a lack of quantitative studies attributing environmental ARG abundance to specific sources. The goal of this study was to evaluate the role of freshwater trout farms in the release and dissemination of ARGs into the environment. Sediment samples upstream and downstream from five rainbow trout farms were collected over time in southern Chile. A microfluidic quantitative polymerase chain reaction approach was used to quantify an ARG array covering different mechanisms of resistance, and data were analyzed using principal component analysis (PCA) and linear mixed regression models. Surveys were also conducted to obtain information about management practices, including antibiotic use, at the farms. Florfenicol and oxytetracycline were used at these farms, although at different rates. A total of 93 samples were analyzed. In the PCA, , , , , (A), (B), (C), (W), and grouped together. A statistically significant increase in abundance of , , , and several genes was found downstream from the farms compared with upstream sites, and retention ponds had the highest ARG abundance at each site. Antibiotic resistance gene levels returned to baseline at an average distance of 132.7 m downstream from the farms. Although results from this study indicate an influence of trout farms on the presence of ARGs in the immediate environment, the extent of their contribution to ARG dissemination is unknown and deserves further investigation.201931589726
6844140.9998Antibiotic resistance genes correlate with metal resistances and accumulate in the deep water layers of the Black Sea. Seas and oceans are a global reservoir of antibiotic resistance genes (ARGs). Only a few studies investigated the dynamics of ARGs along the water column of the Black Sea, a unique environment, with a peculiar geology, biology and history of anthropogenic pollution. In this study, we analyzed metagenomic data from two sampling campaigns (2013 and 2019) collected across three different sites in the Western Black Sea at depths ranging from 5 to 2000 m. The data were processed to annotate ARGs, metal resistance genes (MRGs) and integron integrase genes. The ARG abundance was significantly higher in the deep water layers and depth was the main driver of beta-diversity both for ARGs and MRGs. Moreover, ARG and MRG abundances strongly correlated (r = 0.95). The integron integrase gene abundances and composition were not influenced by the water depth and did not correlate with ARGs. The analysis of the obtained MAGs showed that some of them harbored intI gene together with several ARGs and MRGs, suggesting the presence of multidrug resistant bacteria and that MRGs and integrons could be involved in the selection of ARGs. These results demonstrate that the Black Sea is not only an important reservoir of ARGs, but also that they accumulate in the deep water layers where co-selection with MRGs could be assumed as a relevant mechanism of their persistence.202236030962
7285150.9998Human Activity Determines the Presence of Integron-Associated and Antibiotic Resistance Genes in Southwestern British Columbia. The dissemination of antibiotic resistant bacteria from anthropogenic sources into the environment poses an emerging public health threat. Antibiotic resistance genes (ARGs) and gene-capturing systems such as integron-associated integrase genes (intI) play a key role in alterations of microbial communities and the spread of antibiotic resistant bacteria into the environment. In order to assess the effect of anthropogenic activities on watersheds in southwestern British Columbia, the presence of putative antibiotic resistance and integrase genes was analyzed in the microbiome of agricultural, urban influenced, and protected watersheds. A metagenomics approach and high-throughput quantitative PCR (HT qPCR) were used to screen for elements of resistance including ARGs and intI. Metagenomic sequencing of bacterial genomic DNA was used to characterize the resistome of microbial communities present in watersheds over a 1-year period. There was a low prevalence of ARGs relative to the microbial population (<1%). Analysis of the metagenomic sequences detected a total of 60 elements of resistance including 46 ARGs, intI1, and groEL/intI1 genes and 12 quaternary ammonium compounds (qac) resistance genes across all watershed locations. The relative abundance and richness of ARGs was found to be highest in agriculture impacted watersheds compared to urban and protected watersheds. A downstream transport pattern was observed in the impacted watersheds (urban and agricultural) during dry months. Similar to other reports, this study found a strong association between intI1 and ARGs (e.g., sul1), an association which may be used as a proxy for anthropogenic activities. Chemical analysis of water samples for three major groups of antibiotics was below the detection limit. However, the high richness and gene copy numbers (GCNs) of ARGs in impacted sites suggest that the effects of effluents on microbial communities are occurring even at low concentrations of antimicrobials in the water column. Antibiotic resistance and integrase genes in a year-long metagenomic study showed that ARGs were driven mainly by environmental factors from anthropogenized sites in agriculture and urban watersheds. Environmental factors such as land-use and water quality parameters accounted for 45% of the variability observed in watershed locations.201829765365
3677160.9998Prevalence of sulfonamide-resistant bacteria, resistance genes and integron-associated horizontal gene transfer in natural water bodies and soils adjacent to a swine feedlot in northern Taiwan. Antibiotics are commonly used in swine feed to treat and prevent disease, as well as to promote growth. Antibiotics released into the environment via wastewater could accelerate the emergence of antibiotic-resistant bacteria and resistance genes in the surrounding environment. In this study, we quantified the occurrence of sulfonamides, sulfonamide-resistant microorganisms and resistance genes in the wastewater from a swine farm in northern Taiwan and its surrounding natural water bodies and soils. Sulfonamide levels were similar in the receiving downstream and upstream river water. However, the prevalence of sulfonamide-resistant bacteria and resistance genes, as analyzed by cultivation-dependent and -independent molecular approaches, was significantly greater in the downstream compared to the upstream river water samples. Barcoded-pyrosequencing revealed a highly diverse bacterial community structure in each sample. However, the sequence identity of the sulfonamide resistance gene sul1 in the wastewater and downstream environment samples was nearly identical (99-100%). The sul1 gene, which is genetically linked to class 1 integrons, was dominant in the downstream water bodies and soils. In conclusion, the increased prevalence of sulfonamide resistance genes in the wastewater from a swine farm, independent of the persistent presence of sulfonamides, could be a potential source of resistant gene pools in the surrounding environment.201424637153
3681170.9998A closer look at the antibiotic-resistant bacterial community found in urban wastewater treatment systems. The conventional biological treatment process can provide a favorable environment for the maintenance and dissemination of antibiotic-resistant bacteria and the antibiotic resistance genes (ARG) they carry. This study investigated the occurrence of antibiotic resistance in three wastewater treatment plants (WWTP) to determine the role they play in the dissemination of ARGs. Bacterial isolates resistant to tetracycline were collected, and tested against eight antibiotics to determine their resistance profiles and the prevalence of multiple antibiotic resistance. It was found that bacteria resistant to tetracycline were more likely to display resistance to multiple antibiotics compared to those isolates that were not tetracycline resistant. Polymerase chain reaction (PCR) was used to identify the tetracycline resistance determinants present within the bacterial communities of the WWTPs and receiving waters, and it was found that ARGs may not be released from the treatment process. Identification of isolates showed that there was a large diversity of species in both the tetracycline-resistant and tetracycline-sensitive populations and that the two groups were significantly different in composition. Antibiotic resistance profiles of each population showed that a large diversity of resistance patterns existed within genera suggesting that transmission of ARG may progress by both horizontal gene and vertical proliferation.201829484827
7382180.9998Variation pattern of terrestrial antibiotic resistances and bacterial communities in seawater/freshwater mixed microcosms. The ocean is the final place where pollutants generated by human activities are deposited. As a result, the long-range transport of the ocean can facilitate the diffusion of terrestrial contaminants, including ARGs. However, to our knowledge, little research has been devoted to discussing the content change of terrestrial ARGs and the reason for the change in coastal area. This study established various microcosms, in which seawater and freshwater were mixed at different ratio to simulate the environmental conditions of different regions in coastal areas. Four ARGs were quantified, and 16S pyrosequencing was conducted. The results showed that the terrestrial ARGs influenced the concentration of the corresponding ARGs in coastal areas, and the content change pattern of each ARG was distinct. The influence of salinity on the ARG content was limited in most cases. Moreover, most dominant bacteria from freshwater had significant positive correlation (p < 0.05) with selected ARGs, except for bla(TEM). The dominant bacteria in freshwater diminished dramatically in microcosms with a high proportion of seawater. Freshwater may have a strong impact on the bacteria composition of seawater, and the materials from freshwater may prompt the growth of some bacteria (include potential hosts of ARGs) in coastal area.201829486359
7380190.9998Assessing visitor use impact on antibiotic resistant bacteria and antibiotic resistance genes in soil and water environments of Rocky Mountain National Park. Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been detected in soil and water in close proximity to anthropogenic sources, but the extent to which human impact plays into ARB and ARGs entering the environment is not well described. This study aimed to determine the impact of visitor use on ARB and ARGs in a national park environment. Soil (n = 240) and water (n = 210) samples were collected across a gradient of human activity in Rocky Mountain National Park and analyzed for bacteria resistant to doxycycline, levofloxacin, and vancomycin. Amount of physical effort required to access a sampling site was used as a metric for the likelihood of human presence. A subset of samples was analyzed for the presence and abundance of six ARGs using quantitative polymerase chain reaction. Linear regression analysis demonstrated that anthropogenic factors including hiking effort and proximity to a toilet significantly contributed to the variance of the abundance of ARB for multiple antibiotics in soil and water. Additionally, ecological factors such as water movement, soil texture, and season may play a role in the detection of ARB and ARGs. Predictive analysis suggests that both human presence and human activities, such as waste elimination, significantly contributed to the abundance of ARB in soil and water. The results of this work evidence that the ecology of antibiotic resistance in remote environments is more complex than anthropogenic impact alone, necessitating further environmental characterization of ARB and ARGs.202133932658