Aquaculture changes the profile of antibiotic resistance and mobile genetic element associated genes in Baltic Sea sediments. - Related Documents




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367901.0000Aquaculture 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
367710.9999Prevalence 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
367620.9999Diversity of antibiotic resistance genes and encoding ribosomal protection proteins gene in livestock waste polluted environment. The rapid development and increase of antibiotic resistance are global phenomena resulting from the extensive use of antibiotics in human clinics and animal feeding operations. Antibiotics can promote the occurrence of antibiotic resistance genes (ARGs), which can be transferred horizontally to humans and animals through water and the food chain. In this study, the presence and abundance of ARGs in livestock waste was monitored by quantitative PCR. A diverse set of bacteria and tetracycline resistance genes encoding ribosomal protection proteins (RPPs) from three livestock farms and a river were analyzed through denaturing gradient gel electrophoresis (DGGE). The abundance of sul(I) was 10(3) to 10(5) orders of magnitude higher than that of sul(II). Among 11 tet-ARGs, the most abundant was tet(O). The results regarding bacterial diversity indicated that the presence of antibiotics might have an evident impact on bacterial diversity at every site, particularly at the investigated swine producer. The effect of livestock waste on the bacterial diversity of soil was stronger than that of water. Furthermore, a sequencing analysis showed that tet(M) exhibited two genotypes, while the other RPPs-encoding genes exhibited at least three genotypes. This study showed that various ARGs and RPPs-encoding genes are particularly widespread among livestock.201829469609
368130.9999A 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
740740.9999Impact 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
368050.9999Metagenomic 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
729360.9999Prevalence and transmission of antibiotic resistance and microbiota between humans and water environments. The transmission routes for antibiotic resistance genes (ARGs) and microbiota between humans and water environments is poorly characterized. Here, we used high-throughput qPCR analyses and 16S rRNA gene sequencing to examine the occurrence and abundance of antibiotic resistance genes and microbiota in both healthy humans and associated water environments from a Chinese village. Humans carried the most diverse assemblage of ARGs, with 234 different ARGs being detected. The total abundance of ARGs in feces, on skin, and in the effluent from domestic sewage treatment systems were approximately 23, 2, and 7 times higher than their abundance in river samples. In total, 53 ARGs and 28 bacteria genera that were present in human feces could also be found in the influent and effluent of rural sewage treatment systems, and also downstream of the effluent release point. We identified the bacterial taxa that showed a significant association with ARGs (P < 0.01, r > 0.8) by network analysis, supporting the idea that these bacteria could carry some ARGs and transfer between humans and the environment. Analysis of ARGs and microbiota in humans and in water environments helps to define the transmission routes and dynamics of antibiotic resistance within these environments. This study highlights human contribution to the load of ARGs into the environment and suggests means to prevent such dissemination.201830420129
345470.9999Antibiotic Resistance Genes in Phage Particles from Antarctic and Mediterranean Seawater Ecosystems. Anthropogenic activities are a key factor in the development of antibiotic resistance in bacteria, a growing problem worldwide. Nevertheless, antibiotics and resistances were being generated by bacterial communities long before their discovery by humankind, and might occur in areas without human influence. Bacteriophages are known to play a relevant role in the dissemination of antibiotic resistance genes (ARGs) in aquatic environments. In this study, five ARGs (bla(TEM), bla(CTX-M-1), bla(CTX-M-9), sul1 and tetW) were monitored in phage particles isolated from seawater of two different locations: (i) the Mediterranean coast, subjected to high anthropogenic pressure, and (ii) the Antarctic coast, where the anthropogenic impact is low. Although found in lower quantities, ARG-containing phage particles were more prevalent among the Antarctic than the Mediterranean seawater samples and Antarctic bacterial communities were confirmed as their source. In the Mediterranean area, ARG-containing phages from anthropogenic fecal pollution might allow ARG transmission through the food chain. ARGs were detected in phage particles isolated from fish (Mediterranean, Atlantic, farmed, and frozen), the most abundant being β-lactamases. Some of these particles were infectious in cultures of the fecal bacteria Escherichia coli. By serving as ARG reservoirs in marine environments, including those with low human activity, such as the Antarctic, phages could contribute to ARG transmission between bacterial communities.202032847015
367880.9999Abundance and dynamics of antibiotic resistance genes and integrons in lake sediment microcosms. Antibiotic resistance in bacteria causing disease is an ever growing threat to the world. Recently, environmental bacteria have become established as important both as sources of antibiotic resistance genes and in disseminating resistance genes. Low levels of antibiotics and other pharmaceuticals are regularly released into water environments via wastewater, and the concern is that such environmental contamination may serve to create hotspots for antibiotic resistance gene selection and dissemination. In this study, microcosms were created from water and sediments gathered from a lake in Sweden only lightly affected by human activities. The microcosms were exposed to a mixture of antibiotics of varying environmentally relevant concentrations (i.e., concentrations commonly encountered in wastewaters) in order to investigate the effect of low levels of antibiotics on antibiotic resistance gene abundances and dynamics in a previously uncontaminated environment. Antibiotic concentrations were measured using liquid chromatography-tandem mass spectrometry. Abundances of seven antibiotic resistance genes and the class 1 integron integrase gene, intI1, were quantified using real-time PCR. Resistance genes sulI and ermB were quantified in the microcosm sediments with mean abundances 5 and 15 gene copies/10(6) 16S rRNA gene copies, respectively. Class 1 integrons were determined in the sediments with a mean concentration of 3.8 × 10(4) copies/106 16S rRNA gene copies. The antibiotic treatment had no observable effect on antibiotic resistance gene or integron abundances.201425247418
710690.9999The swine waste resistome: Spreading and transfer of antibiotic resistance genes in Escherichia coli strains and the associated microbial communities. The overuse of antimicrobials in livestock farming has led to the development of resistant bacteria and the spread of antibiotic-resistant genes (ARGs) among animals. When manure containing these antibiotics is applied to agricultural fields, it creates a selective pressure that promotes the acquisition of ARGs by bacteria, primarily through horizontal gene transfer. Most research on ARGs focuses on their role in clinical antibiotic resistance and their transfer from environmental sources to bacteria associated with humans, such as Escherichia coli. The study investigates the spread of antibiotic-resistant genes (ARGs) through class 1 integrons in 27 Escherichia coli strains from pig manure. It focuses on six common ARGs (ermB, cmlA, floR, qnrS, tetA, and TEM) and the class 1 integron gene, assessing their prevalence in manure samples from three pig farms. The study found correlations and anticorrelations among these genes, indicating a predisposition of the integron in spreading certain ARGs. Specifically, cmlA and tetA genes were positively correlated with each other and negatively with int1, suggesting they are not transferred via Int1. Farm B had the highest int1 counts and a higher abundance of the TEM gene, but lower levels of cmlA and tetA genes. The results underscore the complexity of predicting ARG spread in agricultural environments and the associated health risks to humans through the food chain. The study's results offer valuable insights into the antibiotic-resistant genes (ARGs) profile in swine livestock, potentially aiding in the development of methods to trace ARGs in the environment.202439053184
7292100.9999Class 1 integron and related antimicrobial resistance gene dynamics along a complex freshwater system affected by different anthropogenic pressures. The risk for human health posed by polluted aquatic environments, and especially those carrying antibiotic resistance genes (ARGs) of clinical interest, is still debated. This is because of our limited knowledge of the dynamics of antimicrobial resistance in the environment, the selection mechanisms underlying the spread of ARGs, and the ecological factors potentially favoring their return to humans. The Class 1 integron is one of the most effective platforms for the dissemination of ARGs. In this study we investigated a freshwater system consisting of a lake-river-lake continuum, determining the abundance of class 1 integrons and their associated ARGs by a modulated metagenomic approach. Bacterial abundance and community composition were used to identify the potential carriers of class 1 integrons and their associated ARGs over a period of six months. Class 1 integrons and their ARG cargoes were significantly more abundant in riverine sampling sites receiving treated wastewater. Further, class 1 integrons carried ARGs ranked at the highest risk for human health (e.g., catB genes), in particular, genes encoding resistance to aminoglycosides. Genera of potential pathogens, such as Pseudomonas and Escherichia-Shigella, were correlated with class 1 integrons. The lake-river-lake system demonstrated a clear relationship between the integrase gene of class 1 integrons (intI1) and anthropogenic impact, but also a strong environmental filtering that favored the elimination of intI1 once the human derived stressors were reduced. Overall, the results of this study underline the role class 1 integrons as proxy of anthropogenic pollution and suggest this genetic platform as an important driver of aminoglycoside resistance genes, including high risk ARGs, of potential concern for human health.202336351483
3138110.9999Insight into the diversity of antibiotic resistance genes in the intestinal bacteria of shrimp Penaeus vannamei by culture-dependent and independent approaches. Antibiotic resistance genes (ARGs) that distributed in antibiotic resistant bacteria (ARBs) are widespread in aquaculture and have great threats to the aquatic organism as well as to human. However, our understanding about the risk of ARGs to the health of aquatic organism is still limited. In the present study, we got a deep insight into the diversity of ARGs in the intestinal bacteria of shrimp by culture-dependent and independent approaches. Results of the PCR-based detection and culture-dependent analysis indicated that the tetracycline, sulfadiazine, quinolone and erythromycin resistance genes were prevalent in the commercial shrimps that bought from aquatic markets or supermarket. The culture-independent plasmid metagenomic analysis identified 62 different ARGs, which were classified into 21 types, with abundances ranging from 13 to 1418 ppm. The analysis suggested that most of the ARGs come from the plasmids originating from Vibrio (accounted for 2.8-51%) and Aeromonas (accounted for 16-55%), and the Vibrio group was concluded to be the main bacterial pathogen that probably resulted in the shrimp disease. Accordingly, the plasmid metagenomic that focuses on the mobile genetic elements has great potential on the identification of ARGs in complex environments.201930735978
7105120.9999Estimating the contribution of bacteriophage to the dissemination of antibiotic resistance genes in pig feces. The transfer of antibiotic resistance genes (ARGs) in the environment is a threat to both human and animal health. However, the contribution of bacteriophages to the dissemination of resistance genes via transduction is rarely explored. In this study, we screened pig feces from three commercial farms in China for 32 clinically relevant ARG types to assess the presence of the ARG population in bacteria and bacteriophage and further to estimate the contribution of bacteriophages to the dissemination of antibiotic resistance. We found that bacteriophage DNA contained 35.5% of the target ARG types and sul1, bla(TEM) and ermB were found in 100% of the phage DNA samples. The most abundant genes in the bacterial population were ermB and fexA whereas ermB was the most abundant in bacteriophage. In contrast, floR was the least abundant ARG in both populations. Also, the ratio index of the abundance of ARGs in bacteriophage and bacteria was firstly used in this study as an estimator of bacteriophage ability to transmit ARGs. The ratio for qnrA was the greatest (about 10(-1)) and differed from the most abundant bacteriophage ARG ermB. In addition, fexA had the lowest ratio value (about 10(-6)) and not floR. These results illustrate that ARGs abundance and detection rates used alone probably be not suitable for comprehensively judging the contribution of bacteriophage to the dissemination of antibiotic resistance. A more suitable model is the application of three indices; occurrence rate, absolute abundance in bacteriophage and the ratio value as warning and monitoring tools for environmental ARG assessments in bacteriophages.201829573711
5354130.9999Cultivation-dependent and high-throughput sequencing approaches studying the co-occurrence of antibiotic resistance genes in municipal sewage system. During the past years, antibiotic-resistant bacteria (ARB) leading for the spreading of antibiotic resistance genes (ARGs) became a global problem, especially multidrug-resistant (MDR) bacteria are considered the prime culprit of antibiotic resistance. However, the correlation between the antibiotic-resistant phenotype and the ARG profiles remains poorly understood. In the present study, metagenomic functional screening and metagenomic analysis of coliforms were combined to explore the phenotype and genotype of the ARBs from municipal sewage. Our results showed that the ARG co-occurrence was widespread in the municipal sewage. The present study also highlighted the high abundance of ARGs from antibiotic resistance coliforms especially the MDR coliforms with ARG level of 33.8 ± 4.2 copies per cell. The ARG profiles and the antibiotic resistance phenotypes of the isolated antibiotic resistant coliforms were also correlated and indicated that the resistance to the related antibiotic (ampicillin, kanamycin, erythromycin, chloramphenicol, and tetracycline) was mostly contributed by the ARGs belonging to the subtypes of β-lactamase, aminoglycoside 3-phosphotransferase, phosphotransferase type 2, chloramphenicol acetyltransferase, tetA, etc.201729034431
7107140.9999A Comprehensive Study of the Microbiome, Resistome, and Physical and Chemical Characteristics of Chicken Waste from Intensive Farms. The application of chicken waste to farmland could be detrimental to public health. It may contribute to the dissemination of antibiotic-resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) from feces and their subsequent entry into the food chain. The present study analyzes the metagenome and resistome of chicken manure and litter obtained from a commercial chicken farm in Poland. ARB were isolated, identified, and screened for antibiogram fingerprints using standard microbiological and molecular methods. The physicochemical properties of the chicken waste were also determined. ARGs, integrons, and mobile genetic elements (MGE) in chicken waste were analyzed using high-throughput SmartChip qPCR. The results confirm the presence of many ARGs, probably located in MGE, which can be transferred to other bacteria. Potentially pathogenic or opportunistic microorganisms and phytopathogens were isolated. More than 50% of the isolated strains were classified as being multi-drug resistant, and the remainder were resistant to at least one antibiotic class; these pose a real risk of entering the groundwater and contaminating the surrounding environment. Our results indicate that while chicken manure can be sufficient sources of the nutrients essential for plant growth, its microbiological aspects make this material highly dangerous to the environment.202236009027
7414150.9999Structure 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
3683160.9999Small 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
7406170.9999Relationship 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
7395180.9998Impacts of anthropogenic activity on the ecology of class 1 integrons and integron-associated genes in the environment. The impact of human activity on the selection for antibiotic resistance in the environment is largely unknown, although considerable amounts of antibiotics are introduced through domestic wastewater and farm animal waste. Selection for resistance may occur by exposure to antibiotic residues or by co-selection for mobile genetic elements (MGEs) which carry genes of varying activity. Class 1 integrons are genetic elements that carry antibiotic and quaternary ammonium compound (QAC) resistance genes that confer resistance to detergents and biocides. This study aimed to investigate the prevalence and diversity of class 1 integron and integron-associated QAC resistance genes in bacteria associated with industrial waste, sewage sludge and pig slurry. We show that prevalence of class 1 integrons is higher in bacteria exposed to detergents and/or antibiotic residues, specifically in sewage sludge and pig slurry compared with agricultural soils to which these waste products are amended. We also show that QAC resistance genes are more prevalent in the presence of detergents. Studies of class 1 integron prevalence in sewage sludge amended soil showed measurable differences compared with controls. Insertion sequence elements were discovered in integrons from QAC contaminated sediment, acting as powerful promoters likely to upregulate cassette gene expression. On the basis of this data, >1 × 10(19) bacteria carrying class 1 integrons enter the United Kingdom environment by disposal of sewage sludge each year.201121368907
3472190.9998Selective pressure governs the composition, antibiotic, and heavy metal resistance profiles of Aeromonas spp. isolated from Ba River in Northwest China. The selective pressure of the living surroundings is a key factor in the development of resistance profiles in pathogenic bacteria such as Aeromonas spp. In this study, Aeromonas species were isolated from the Ba River, and their composition, resistance profiles to antibiotics, and heavy metals (HMs) were investigated. The discovery revealed that selective pressure altered the diversity of Aeromonas spp., with Aeromonas veronii being more adaptable to contaminated waters. Long-term exposure to antibiotics or HMs exerts persistent selective pressure on Aeromonas species, leading to the increase in multiple antibiotic resistance (MAR) index and multidrug-resistant (MDR) strains. Furthermore, HMs could drive the co-selection of antibiotic resistance via co-resistance or cross-resistance. bla(TEM), bla(SHV), bla(CTX-M), sul1, czcA, mexA, and mexF were detected at high frequencies in Aeromonas species. Among these resistance phenotypes conferred genes, bla(TEM) may be intrinsic in the genome of Aeromonas spp., while mexA and mexF may have been acquired from surrounding environments owing to selective pressure. Resistance genes evolved as a consequence of selective pressure and have been shown to be positively correlated with their prevalence. Our study suggests that the selective pressure of living surroundings significantly contributes to the composition and resistance profiles of Aeromonas spp. in the riverine ecosystem.202235657546