The Impact of Urban Pollution on Plasmid-Mediated Resistance Acquisition in Enterobacteria from a Tropical River. - Related Documents




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344701.0000The Impact of Urban Pollution on Plasmid-Mediated Resistance Acquisition in Enterobacteria from a Tropical River. Background: The exposure of environmental bacteria to contaminants in aquatic ecosystems accelerates the dissemination of antibiotic-resistance genes (ARGs) through horizontal gene transfer (HGT). Methods: In this study, we sampled three locations along a contamination gradient of a polluted river, focusing on isolating Enterobacteria from the surface waters to investigate the relationship between urban pollution and antibiotic resistance. The genomes of 15 isolates (5 per site) were sequenced to identify plasmid-borne ARGs and their association with resistance phenotypes. Results: Isolates from the site with the highest contamination (Site 3) showeda larger number of ARGs, plasmids, and resistance phenotypes. Notably, one of the isolates analyzed, E. coli A231-12, exhibited phenotypic resistance to seven antibiotics, presumably conferred by a single plasmid carrying 12 ARGs. Comparative analysis of this plasmid revealed its close evolutionary relationship with another IncH plasmid hosted by Salmonella enterica, underscoring its high ARG burden in the aquatic environment. Other plasmids identified in our isolates carried sul and dfrA genes, conferring resistance to trimethoprim/sulfamethoxazole, a commonly prescribed antibiotic combination in clinical settings. Conclusions: These results highlight the critical need to expand research on the link between pollution and plasmid-mediated antimicrobial resistance in aquatic ecosystems, which can act as reservoirs of ARGs.202439596782
344610.9999Prevalence and transmission risk of colistin and multidrug resistance in long-distance coastal aquaculture. Due to the wide use of antibiotics, intensive aquaculture farms have been recognized as a significant reservoir of antibiotic resistomes. Although the prevalence of colistin resistance genes and multidrug-resistant bacteria (MDRB) has been documented, empirical evidence for the transmission of colistin and multidrug resistance between bacterial communities in aquaculture farms through horizontal gene transfer (HGT) is lacking. Here, we report the prevalence and transmission risk of colistin and multidrug resistance in 27 aquaculture water samples from 9 aquaculture zones from over 5000 km of subtropical coastlines in southern China. The colistin resistance gene mcr-1, mobile genetic element (MGE) intl1 and 13 typical antibiotic resistance genes (ARGs) were prevalent in all the aquaculture water samples. Most types of antibiotic (especially colistin) resistance are transmissible in bacterial communities based on evidence from laboratory conjugation and transformation experiments. Diverse MDRB were detected in most of the aquaculture water samples, and a strain with high-level colistin resistance, named Ralstonia pickettii MCR, was isolated. The risk of horizontal transfer of the colistin resistance of R. pickettii MCR through conjugation and transformation was low, but the colistin resistance could be steadily transmitted to offspring through vertical transfer. The findings have important implications for the future regulation of antibiotic use in aquaculture farms globally to address the growing threat posed by antibiotic resistance to human health.202337935916
335620.9999Conjugative multiple-antibiotic resistance plasmids in Escherichia coli isolated from environmental waters contaminated by human faecal wastes. AIMS: To better understand the involvement of faecal contamination in the dissemination of antibiotic resistance genes, we investigated the genetic supports of resistances in nine multi-resistant Escherichia coli strains originating from human faecal contamination, and isolated from three different aquatic environments used for producing drinking water. METHODS AND RESULTS: Seven strains harboured at least one large plasmid that we have characterized (size, antibiotic resistance patterns, incompatibility group, capacity of autotransfer, presence of integron). Most of these plasmids were conjugative and carried numerous resistances. One of the plasmids studied, belonging to the IncP incompatibility group, was able to transfer by conjugation to Pseudomonas fluorescens and Aeromonas sp. Only two of the plasmids we studied carried class 1 and/or 2 integron(s). CONCLUSIONS: Conjugative plasmids isolated from multi-resistant E. coli strains explained most of the resistances of their host strains and probably contribute to the spread of antibiotic resistance genes coming from human faecal contamination. SIGNIFICANCE AND IMPACT OF THE STUDY: These results highlight the key role played by plasmids in the multi-resistance phenotype of faecal bacteria and the diversity of these genetic structures. Contaminated water, especially accidentally contaminated drinking water, could be a path back to humans for these plasmids.201525387599
335330.9999Plasmid and integron-associated antibiotic resistance in Escherichia coli isolated from domestic wastewater treatment plants. The rapid dissemination of antibiotic resistance genes (ARGs) represents a significant global threat, with wastewater treatment plants (WWTPs) playing an important role as reservoirs and propagation hubs. In this study, we performed whole-genome sequencing and bioinformatic analyses on eight multidrug-resistant Escherichia coli isolates previously obtained from domestic WWTPs in Costa Rica. We identified 61 ARGs (23 unique), with 40 located on plasmids, and 21 on chromosomal sequences, seven of which were within integrons. Several ARGs were associated with resistance to clinically and veterinary important antibiotics, including sulfamethoxazole/trimethoprim, beta-lactams, and tetracyclines. One hundred twenty-one virulence-associated genes (29 unique) were detected, with 16 located on plasmids. Notably, the presence of virulence factors such as ompT and hlyF genes alongside ARGs on plasmids underscores the transmissible pathogenic potential of WWTP-associated E. coli strains. These findings highlight the role of small domestic WWTPs in disseminating pathogenic and multidrug-resistant bacteria and their mobile genetic elements, emphasizing the need for further research to understand how these discharges impact aquatic environments.202540246693
498740.9998The Human Health Implications of Antibiotic Resistance in Environmental Isolates from Two Nebraska Watersheds. One Health field-based approaches are needed to connect the occurrence of antibiotics present in the environment with the presence of antibiotic resistance genes (ARGs) in Gram-negative bacteria that confer resistance to antibiotics important in for both veterinary and human health. Water samples from two Nebraska watersheds influenced by wastewater effluent and agricultural runoff were tested for the presence of antibiotics used in veterinary and human medicine. The water samples were also cultured to identify the bacteria present. Of those bacteria isolated, the Gram-negative rods capable of causing human infections had antimicrobial susceptibility testing and whole-genome sequencing (WGS) performed to identify ARGs present. Of the 211 bacterial isolates identified, 37 belonged to pathogenic genera known to cause human infections. Genes conferring resistance to beta-lactams, aminoglycosides, fosfomycins, and quinolones were the most frequently detected ARGs associated with horizontal gene transfer (HGT) in the watersheds. WGS also suggest recent HGT events involving ARGs transferred between watershed isolates and bacteria of human and animal origins. The results of this study demonstrate the linkage of antibiotics and bacterial ARGs present in the environment with potential human and/or veterinary health impacts. IMPORTANCE One health is a transdisciplinary approach to achieve optimal health for humans, animals, plants and their shared environment, recognizing the interconnected nature of health in these domains. Field based research is needed to connect the occurrence of antibiotics used in veterinary medicine and human health with the presence of antibiotic resistance genes (ARGs). In this study, the presence of antibiotics, bacteria and ARGs was determined in two watersheds in Nebraska, one with agricultural inputs and the other with both agricultural and wastewater inputs. The results presented in this study provide evidence of transfer of highly mobile ARG between environment, clinical, and animal-associated bacteria.202235311538
346950.9998Antibiotic resistance genes of emerging concern in municipal and hospital wastewater from a major Swedish city. The spread of antibiotic resistance among bacterial pathogens is to a large extent mediated by mobile antibiotic resistance genes (ARGs). The prevalence and geographic distribution of several newly discovered ARGs, as well as some clinically important ARGs conferring resistance to last resort antibiotics, are largely unknown. Targeted analysis of wastewater samples could allow estimations of carriage in the population connected to the sewers as well as release to the environment. Here we quantified ARGs conferring resistance to linezolid (optrA and cfr(A)) and colistin (mcr-1, -2, -3, -4 and -5) and the recently discovered gar (aminoglycoside ARG) and sul4 (sulphonamide ARG) in raw hospital and municipal wastewater as well as treated municipal wastewater during five years in a low antibiotic resistance prevalence setting (Gothenburg, Sweden). Additionally, variations in bacterial composition of the wastewaters characterized by 16S rRNA sequencing were related to the variations of the ARGs in an attempt to reveal if the presence of known or suspected bacterial host taxa could explain the presence of the ARGs in wastewater. The mcr-1, mcr-3, mcr-4, mcr-5, sul4 and gar genes were detected regularly in all types of wastewater samples while optrA and cfr(A) were detected only in hospital wastewater. The most abundant genes were mcr-3 and mcr-5, especially in municipal wastewater. The detection of optrA was restricted to a peak during one year. Most of the ARGs correlated with taxa previously described as bacterial hosts and associated with humans. Although some of the tentative hosts may include bacteria also thriving in wastewater environments, detection of the ARGs in the wastewaters could reflect their presence in the gut flora of the contributing populations. If so, they could already today or in the near future hinder treatment of bacterial infections in a setting where they currently are rarely targeted/detected during clinical surveillance.202234748849
347860.9998Bacterial plasmid-mediated quinolone resistance genes in aquatic environments in China. Emerging antimicrobial resistance is a major threat to human's health in the 21(st) century. Understanding and combating this issue requires a full and unbiased assessment of the current status on the prevalence of antimicrobial resistance genes and their correlation with each other and bacterial groups. In aquatic environments that are known reservoirs for antimicrobial resistance genes, we were able to reach this goal on plasmid-mediated quinolone resistance (PMQR) genes that lead to resistance to quinolones and possibly also to the co-emergence of resistance to β-lactams. Novel findings were made that qepA and aac-(6')-Ib genes that were previously regarded as similarly abundant with qnr genes are now dominant among PMQR genes in aquatic environments. Further statistical analysis suggested that the correlation between PMQR and β-lactam resistance genes in the environment is still weak, that the correlations between antimicrobial resistance genes could be weakened by sufficient wastewater treatment, and that the prevalence of PMQR has been implicated in environmental, pathogenic, predatory, anaerobic, and more importantly, human symbiotic bacteria. This work provides a comprehensive analysis of PMQR genes in aquatic environments in Jinan, China, and provides information with which combat with the antimicrobial resistance problem may be fought.201728094345
340870.9998The role of aquatic ecosystems as reservoirs of antibiotic resistant bacteria and antibiotic resistance genes. The widespread and indiscriminate use of antibiotics has led to the development of antibiotic resistance in pathogenic, as well as commensal, microorganisms. Resistance genes may be horizontally or vertically transferred between bacterial communities in the environment. The recipient bacterial communities may then act as a reservoir of these resistance genes. In this study, we report the incidence of antibiotic resistance in enteric bacteria isolated from the Mhlathuze River and the distribution of genetic elements that may be responsible for the observed antibiotic resistance. The resistance of the enteric bacteria isolated over a period of one year showed that resistance to the older classes of antibiotics was high (94.7% resistance to one antibiotic and 80.8% resistance to two antibiotics). Furthermore, antibiotic resistance data of the environmental isolates showed a strong correlation (r = 0.97) with data obtained from diarrhoea patients. PCR based methods demonstrated that class 1 integrons were present in >50% of the environmental bacterial isolates that were resistant to multiple antibiotics. This class of integrons is capable of transferring genes responsible for resistance to beta-lactam, aminoglycoside, sulfonamide and quaternary ammonium antimicrobial agents. Conjugate plasmids were also isolated, but from a small percentage of isolates. This study showed that the Mhlathuze River (a) is a medium for the spread of bacterial antibiotic resistance genes, (b) acts as a reservoir for these genes and (c) due to socio-economic pressures, may play a role in the development and evolution of these genes along this river system.200415318485
318580.9998Differences in co-selection and localization of antimicrobial resistance and virulence genes among Acinetobacter isolates from patients, pig waste, and the environment. Acinetobacter species are indigenous bacteria in water environments, whereas in clinical settings, they can pose a serious risk of nosocomial infection as opportunistic pathogens harboring multidrug-resistance genes. Understanding the similarities and differences in pathogenicity and drug resistance among Acinetobacter strains isolated from animals, humans, and the environment through a One Health approach is essential for mitigating their infection risk. We explored the resistome and virulome of 38 Acinetobacter isolates obtained from pigs' waste, patients, wastewater, and wastewater-impacted environments, including river and coastal area which receives wastewater effluent. Hybrid genome assemblies demonstrated distinct difference in the composition and location of antibiotic resistance genes (ARGs). Patient- and environment-associated isolates demonstrated chromosomally integrated ARGs and genes encoding efflux pumps, whereas pig waste-associated isolates exhibited a diverse range of ARG types predominantly located on plasmid replicons. Additionally, an analysis of virulence genes (VGs) across all Acinetobacter isolates revealed that VGs are more prevalent in patient- and environment-associated isolates compared to pig waste-associated isolates. Notably, a positive correlation between the number of ARGs and VGs located on the chromosome was observed in environment-associated isolates, which may imply co-selection of ARGs and VGs. Overall, this study highlights differences in the localization and co-selection of ARGs and VGs among patient-, pig waste-, and environment- associated isolates, suggesting that Acinetobacter spp. adapted to the human body tend to possess VGs and ARGs together, while those derived from animals may preferentially harbor transferable ARGs.202541039664
346590.9998Role of Flies in the Maintenance of Antimicrobial Resistance in Farm Environments. Flies play an important role as vectors in the transmission of antimicrobial-resistant bacteria (ARB) and are hypothesized to transfer ARB between internal and external livestock housing areas. The aim of this study was to understand the role that flies may play in the maintenance of ARB in the farm environment. We first evaluated the fate of ingested antimicrobial-resistant Escherichia coli harboring a plasmid containing antimicrobial-resistance genes (ARGs) throughout the housefly (Musca domestica) life cycle, from adult to the subsequent F1 generation. Antimicrobial-resistant E. coli was isolated from different life cycle stages and ARG carriage quantified. The ingested E. coli persisted throughout the fly life cycle, and ARG carriage was maintained at a constant level in the housefly microbiota. To clarify the transmission of ARB from flies to livestock, 30-day-old chickens were inoculated with maggots containing antimicrobial-resistant E. coli. Based on the quantification of bacteria isolated from cecal samples, antimicrobial-resistant E. coli persisted in these chickens for at least 16 days. These results suggest that flies act as a reservoir of ARB throughout their life cycle and may therefore be involved in the maintenance and circulation of ARB in the farm environment.201929708845
4993100.9998The role of the natural aquatic environment in the dissemination of extended spectrum beta-lactamase and carbapenemase encoding genes: A scoping review. The natural aquatic environment is a significant contributor to the development and circulation of clinically significant antibiotic resistance genes (ARGs). The potential for the aquatic environment to act as a reservoir for ARG accumulation in areas receiving anthropogenic contamination has been thoroughly researched. However, the emergence of novel ARGs in the absence of external influences, as well as the capacity of environmental bacteria to disseminate ARGs via mobile genetic elements remain relatively unchallenged. In order to address these knowledge gaps, this scoping literature review was established focusing on the detection of two important and readily mobile ARGs, namely, extended spectrum beta-lactamase (ESBL) and carbapenemase genes. This review included 41 studies from 19 different countries. A range of different water bodies including rivers (n = 26), seawaters (n = 6) and lakes (n = 3), amongst others, were analysed in the included studies. ESBL genes were reported in 29/41 (70.7%) studies, while carbapenemase genes were reported in 13/41 (31.7%), including joint reporting in 9 studies. The occurrence of mobile genetic elements was evaluated, which included the detection of integrons (n = 22), plasmids (n = 18), insertion sequences (n = 4) and transposons (n = 3). The ability of environmental bacteria to successfully transfer resistance genes via conjugation was also examined in 11 of the included studies. The findings of this scoping review expose the presence of clinically significant ARGs in the natural aquatic environment and highlights the potential ability of environmental isolates to disseminate these genes among different bacterial species. As such, the results presented demonstrate how anthropogenic point discharges may not act as the sole contributor to the development and spread of clinically significant antibiotic resistances. A number of critical knowledge gaps in current research were also identified. Key highlights include the limited number of studies focusing on antibiotic resistance in uncontaminated aquatic environments as well as the lack of standardisation among methodologies of reviewed investigations.202032438141
3466110.9998Behavior of last resort antibiotic resistance genes (mcr-1 and bla(NDM-1)) in a drinking water supply system and their possible acquisition by the mouse gut flora. Mcr-1 and bla(NDM-1) antibiotic resistance genes (ARGs) confer resistance to colistins and carbapenems, which are often antibiotics used as a last resort in tertiary care hospitals. Dissemination of these two ARGs in drinking water supply systems and their effect on healthy gut bacteria are poorly studied. In this study, the dissemination of mcr-1 and bla(NDM-1) in a drinking water supply system, and their effect on the antibiotic resistance of mouse gut bacteria are explored. Metagenome analysis revealed that source water (Taipu river and Jinze reservoir) was polluted with ARGs. Mcr-1 and bla(NDM-1) can be disseminated through the water distribution system. Even advanced water treatments (ozone and biological activated carbon (BAC)) could not effectively remove mcr-1 and bla(NDM-1). Low concentrations of chloramine disinfectants in the water distribution system were not effective at limiting ARG abundance. Mobile genetic elements were also found to play a major role in the dissemination of ARGs via horizontal gene transfer (HGT) throughout the water supply system. Statistical analysis revealed that there was no effect of temperature on the abundance of mcr-1 and bla(NDM-1) throughout the water supply system. A last resort ARG, mcr-1 can disseminate from drinking water to the healthy mouse gut. The presence of mcr-1 in a strain belonging to Enterococcus hirae, which is different from the strain belonging to the Bacillus cereus group isolated from drinking water, strongly supports the phenomena of HGT inside the gut. This research provides novel insights into the role of drinking water in disseminating ARGs to the gut and strongly suggests that drinking water may also play a major role apart from other factors known to be involved in the prevalence of last resort ARGs in the gut.202031896482
3352120.9998Analysis of antibiotic multi-resistant bacteria and resistance genes in the effluent of an intensive shrimp farm (Long An, Vietnam). In Vietnam, intensive shrimp farms heavily rely on a wide variety of antibiotics (ABs) to treat animals or prevent disease outbreak. Potential for the emergence of multi-resistant bacteria is high, with the concomitant contamination of adjacent natural aquatic habitats used for irrigation and drinking water, impairing in turn human health system. In the present study, quantification of AB multi-resistant bacteria was carried out in water and sediment samples from effluent channels connecting a shrimp farming area to the Vam Co River (Long An Province, Vietnam). Bacterial strains, e.g. Klebsiella pneumoniae and Aeromonas hydrophila, showing multi-resistance traits were isolated. Molecular biology analysis showed that these strains possessed from four to seven different AB resistance genes (ARGs) (e.g. sul1, sul2, qnrA, ermB, tetA, aac(6)lb, dfrA1, dfr12, dfrA5), conferring multidrug resistance capacity. Sequencing of plasmids present within these multi-resistant strains led to the identification of a total of forty-one resistance genes, targeting nine AB groups. qPCR analysis on the sul2 gene revealed the presence of high copy numbers in the effluent channel connecting to the Vam Co River. The results of the present study clearly indicated that multi-resistant bacteria present in intensive shrimp cultures may disseminate in the natural environment. This study offered a first insight in the impact of plasmid-born ARGs and the related pathogenic bacteria that could emerged due to inappropriate antibiotic utilization in South Vietnam.201829524670
3370130.9998Microbiological contamination and resistance genes in biofilms occurring during the drinking water treatment process. Biofilms are the predominant mode of microbial growth in drinking water systems. A dynamic exchange of individuals occurs between the attached and planktonic populations, while lateral gene transfer mediates genetic exchange in these bacterial communities. Integrons are important vectors for the spread of antimicrobial resistance. The presence of class 1 integrons (intI1, qac and sul genes) was assessed in biofilms occurring throughout the drinking water treatment process. Isolates from general and specific culture media, covering a wide range of environmental bacteria, fecal indicators and opportunistic pathogens were tested. From 96 isolates tested, 9.37% were found to possess genetic determinants of putative antimicrobial resistance, and these occurred in both Gram-positive and Gram-negative bacteria. Class 1 integron integrase gene was present in 8.33% of bacteria, all positive for the qacEΔ1 gene. The sul1 gene was present in 3.12% of total isolates, representing 37.5% of the class 1 integron positive cells. The present study shows that biofilm communities in a drinking water treatment plant are a reservoir of class 1 integrons, mainly in bacteria that may be associated with microbiological contamination. Eight out of nine integron bearing strains (88.8%) were identified based on 16S rRNA gene sequencing as either enteric bacteria or species that may be connected to animal and anthropogenic disturbance.201323247295
3445140.9998Horizontal plasmid transfer promotes antibiotic resistance in selected bacteria in Chinese frog farms. The emergence and dissemination of antibiotic resistance genes (ARGs) in the ecosystem are global public health concerns. One Health emphasizes the interconnectivity between different habitats and seeks to optimize animal, human, and environmental health. However, information on the dissemination of antibiotic resistance genes (ARGs) within complex microbiomes in natural habitats is scarce. We investigated the prevalence of antibiotic resistant bacteria (ARB) and the spread of ARGs in intensive bullfrog (Rana catesbeiana) farms in the Shantou area of China. Antibiotic susceptibilities of 361 strains, combined with microbiome analyses, revealed Escherichia coli, Edwardsiella tarda, Citrobacter and Klebsiella sp. as prevalent multidrug resistant bacteria on these farms. Whole genome sequencing of 95 ARB identified 250 large plasmids that harbored a wide range of ARGs. Plasmid sequences and sediment metagenomes revealed an abundance of tetA, sul1, and aph(3″)-Ib ARGs. Notably, antibiotic resistance (against 15 antibiotics) highly correlated with plasmid-borne rather than chromosome-borne ARGs. Based on sequence similarities, most plasmids (62%) fell into 32 distinct groups, indicating a potential for horizontal plasmid transfer (HPT) within the frog farm microbiome. HPT was confirmed in inter- and intra-species conjugation experiments. Furthermore, identical mobile ARGs, flanked by mobile genetic elements (MGEs), were found in different locations on the same plasmid, or on different plasmids residing in the same or different hosts. Our results suggest a synergy between MGEs and HPT to facilitate ARGs dissemination in frog farms. Mining public databases retrieved similar plasmids from different bacterial species found in other environmental niches globally. Our findings underscore the importance of HPT in mediating the spread of ARGs in frog farms and other microbiomes of the ecosystem.202439089095
3140150.9998Uncovering the diversity and contents of gene cassettes in class 1 integrons from the endophytes of raw vegetables. Rapid spread of antibiotic resistance genes (ARGs) in pathogens is threatening human health. Integrons allow bacteria to integrate and express foreign genes, facilitating horizontal transfer of ARGs in environments. Consumption of raw vegetables represents a pathway for human exposure to environmental ARGs. However, few studies have focused on integron-associated ARGs in the endophytes of raw vegetables. Here, based on the approach of qPCR and clone library, we quantified the abundance of integrase genes and analyzed the diversity and contents of resistance gene cassettes in class 1 integrons from the endophytes of six common raw vegetables. The results revealed that integrase genes for class 1 integron were most prevalent compared with class 2 and class 3 integron integrase genes (1-2 order magnitude, P < 0.05). The cucumber endophytes harbored a higher absolute abundance of integrase genes than other vegetables, while the highest bacterial abundance was detected in cabbage and cucumber endophytes. Thirty-two unique resistance gene cassettes were detected, the majority of which were associated with the genes encoding resistance to beta-lactam and aminoglycoside. Antibiotic resistance gene cassettes accounted for 52.5 % of the functionally annotated gene cassettes, and bla(TEM-157) and aadA2 were the most frequently detected resistance cassettes. Additionally, carrot endophytes harbored the highest proportion of antibiotic resistance gene cassettes in the class 1 integrons. Collectively, these results provide an in-depth view of acquired resistance genes by integrons in the raw vegetable endophytes and highlight the potential health risk of the transmission of ARGs via the food chain.202236371907
3443160.9998A hybrid DNA sequencing approach is needed to properly link genotype to phenotype in multi-drug resistant bacteria. Antibiotic resistance genes (ARGs) are now viewed as emerging contaminants posing a potential worldwide human health risk. The degree to which ARGs are transferred to other bacteria via mobile genetic elements (MGEs), including insertion sequences (ISs), plasmids, and phages, has a strong association with their likelihood to function as resistance transfer determinants. Consequently, understanding the structure and function of MGEs is paramount to assessing future health risks associated with ARGs in an environment subjected to strong antibiotic pressure. In this study we used whole genome sequencing, done using MinION and HiSeq platforms, to examine antibiotic resistance determinants among four multidrug resistant bacteria isolated from fish farm effluent in Jeju, South Korea. The combined data was used to ascertain the association between ARGs and MGEs. Hybrid assembly using HiSeq and MinION reads revealed the presence of IncFIB(K) and pVPH2 plasmids, whose sizes were verified using pulsed field gel electrophoresis. Twenty four ARGs and 95 MGEs were identified among the 955 coding sequences annotated on these plasmids. More importantly, 22 of 24 ARGs conferring resistance to various antibiotics were found to be located near MGEs, whereas about a half of the ARGs (11 out of 21) were so in chromosomes. Our results also suggest that the total phenotypic resistance exhibited by the isolates was mainly contributed by these putatively mobilizable ARGs. The study gives genomic insights into the origins of putatively mobilizable ARGs in bacteria subjected to selection pressure.202134330011
3406170.9998Environmental and Pathogenic Carbapenem Resistant Bacteria Isolated from a Wastewater Treatment Plant Harbour Distinct Antibiotic Resistance Mechanisms. Wastewater treatment plants are important reservoirs and sources for the dissemination of antibiotic resistance into the environment. Here, two different groups of carbapenem resistant bacteria-the potentially environmental and the potentially pathogenic-were isolated from both the wastewater influent and discharged effluent of a full-scale wastewater treatment plant and characterized by whole genome sequencing and antibiotic susceptibility testing. Among the potentially environmental isolates, there was no detection of any acquired antibiotic resistance genes, which supports the idea that their resistance mechanisms are mainly intrinsic. On the contrary, the potentially pathogenic isolates presented a broad diversity of acquired antibiotic resistance genes towards different antibiotic classes, especially β-lactams, aminoglycosides, and fluoroquinolones. All these bacteria showed multiple β-lactamase-encoding genes, some with carbapenemase activity, such as the bla(KPC)-type genes found in the Enterobacteriaceae isolates. The antibiotic susceptibility testing assays performed on these isolates also revealed that all had a multi-resistance phenotype, which indicates that the acquired resistance is their major antibiotic resistance mechanism. In conclusion, the two bacterial groups have distinct resistance mechanisms, which suggest that the antibiotic resistance in the environment can be a more complex problematic than that generally assumed.202134572700
3681180.9998A 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
3475190.9998Phylogenomics of novel clones of Aeromonas veronii recovered from a freshwater lake reveals unique biosynthetic gene clusters. Aquatic ecosystems serve as crucial reservoirs for pathogens and antimicrobial resistance genes, thus presenting a significant global health risk. Here, we investigated the phylogenomics of Aeromonas veronii from Lake Wilcox in Ontario. Among the 11 bacterial isolates, nine were identified as A. veronii. Notably, 67% of A. veronii isolates were potential human pathogens. Considerable genetic diversity was noted among the A. veronii isolates, suggesting the lake as a reservoir for multiple human pathogenic strains. Comparison of the A. veronii sequenced with global A. veronii genomes highlighted significant genetic diversity and suggests widespread dissemination of strains. All the isolates carried chromosomal genes encoding resistance to β-lactams. Although virulence gene content differed between human and non-human pathogenic strains, type III secretion systems was associated with human pathogenic isolates. The assessment of AMR genes in global isolates showed that β-lactam and tetracycline resistance genes were predominant. Although the machine learning-based pangenome-wide association approach performed did not yield any source-based genes, some genes were enriched in a few isolates from different sources. The mrkABCDF operon that mediates biofilm formation and genes encoding resistance to colistin, chloramphenicol, trimethoprim, and tetracycline were enriched in animal products, whereas macrolide resistance genes and Inc plasmid-types were linked to the aquatic environment. Novel biosynthetic gene clusters were identified, suggesting that A. veronii with varying pathogenic potential could produce unique secondary metabolites. There is a need for continuous tracking of pathogens in aquatic ecosystems to contribute to our understanding of their evolutionary dynamics and the ecological roles of their genetic elements. IMPORTANCE: Lakes and other aquatic ecosystems can harbor harmful bacteria that can make people sick and resist antibiotics, posing a significant global health risk. In this study, we investigated Aeromonas veronii, a Gram-negative bacteria found in Lake Wilcox in Ontario. We used various techniques, including whole-genome sequencing (WGS), to analyze the bacteria and found that many of the isolates had the potential to cause human disease. We also discovered significant genetic diversity among the isolates, indicating that the lake may be a reservoir for multiple human pathogenic strains. All isolates carried genes that confer resistance to antibiotics, and some virulence genes were associated with human pathogenic isolates. This study highlights the importance of monitoring aquatic ecosystems for harmful bacteria to better understand their evolution, potential for human pathogenicity, and the ecological roles of their genetic elements. This knowledge can inform strategies for preventing the spread of antibiotic-resistant bacteria and protecting public health.202439513706