Spread Of Antibiotic Resistance Genes Research Articles

The interplay between mobilome and resistome in Staphylococcus aureus.

Antibiotic resistance genes (ARGs) in Staphylococcus aureus can disseminate vertically through successful clones, but also horizontally through the transfer of genes conveyed by mobile genetic elements (MGEs). Even though underexplored, MGE/ARG associations in S. aureus favor the emergence of multidrug-resistant clones, which are challenging therapeutic success in both human and animal health. This study investigated the interplay between the mobilome and the resistome of more than 10,000 S. aureus genomes from human and animal origin. The analysis revealed a remarkable diversity of MGEs and ARGs, with plasmids and transposons being the main carriers of ARGs. Numerous MGE/ARG associations were identified, suggesting that MGEs play a critical role in the dissemination of resistance. A high degree of similarity was observed in MGE/ARG associations between human and animal isolates, highlighting the potential for unrestricted spread of ARGs between hosts. Our results showed that in parallel to clonal expansion, MGEs and their associated ARGs can spread across different strain types sequence types (STs), favoring the evolution of these clones and their adaptation in selective environments. The high variability of MGE/ARG associations within individual STs and their spread across several STs highlight the crucial role of MGEs in shaping the S. aureus resistome. Overall, this study provides valuable insights into the complex interplay between MGEs and ARGs in S. aureus, emphasizing the need to elucidate the mechanisms governing the epidemic success of MGEs, particularly those implicated in ARG transfer.IMPORTANCEThe research presented in this article highlights the importance of understanding the interactions between mobile genetic elements (MGEs) and antibiotic resistance genes (ARGs) carried by Staphylococcus aureus, a versatile bacterium that can be both a harmless commensal and a dangerous pathogen for humans and animals. S. aureus has a great capacity to acquire and disseminate ARGs, enabling efficient adaption to various environmental or clinical conditions. By analyzing a large data set of S. aureus genomes, we highlighted the substantial role of MGEs, particularly plasmids and transposons, in disseminating ARGs within and between S. aureus populations, bypassing host barriers. Given that multidrug-resistant S. aureus strains are classified as a high-priority pathogen by global health organizations, this knowledge is crucial for understanding the complex dynamics of transmission of antibiotic resistance in this species.

Distribution and drivers of co−hosts of antibiotic and metal(loid) resistance genes in the fresh−brackish−saline groundwater

Groundwater is an essential source of drinking water and agricultural irrigation water, and its protection has become a global goal for public health. However, knowledge about heavy metal(loid) resistance genes (MRGs) in groundwater and the potential co−selection of antibiotic resistance genes (ARGs) have seldom been developed. Here, during the wet and dry seasons, we collected 66 groundwater samples (total dissolved solids = 93.9−9530 mg/L) adjacent to Baiyangdian Lake in Northern China, which presented the few metal(loid) and antibiotic contamination. We identified 160 MRGs whose composition exhibited significant seasonal variation, and dissolved metal(loid)s (particularly Ba) played a determinative role in promoting the MRGs proliferation though with relatively low concentrations, suggesting the relatively vulnerable groundwater ecosystems. Moreover, 27.4% of MRG−carrying metagenome−assembled genomes (MAGs) simultaneously carried ARGs, with the most frequently detected MRG types of Cu, Hg, and As, and ARG types of multidrug and bacitracin. Physicochemical variables, variables related to total dissolved solids, metal(loid)s, and antibiotics synthetically shaped the variation of MRG−ARG hosts in groundwater. We found that the increase of MRG−ARG hosts was critically responsible for the spread of MRGs and ARGs in groundwater. Our findings revealed the widespread co−occurrence of MRGs and ARGs in few−contaminated groundwater and highlighted the crucial roles of salinity in their propagation and transmission.

Engineering probiotic Escherichia coli Nissle 1917 to block transfer of multiple antibiotic resistance genes by exploiting a type I CRISPR-Cas system.

To reduce the development of antibiotic resistance, probiotics have been considered as a substitute for antibiotics. However, probiotics themselves are reservoirs of antibiotic resistance genes (ARGs). This study introduces a new strategy for limiting the spread of ARGs by engineering the typical probiotic strain Escherichia coli Nissle 1917 (EcN), which has been used for treating intestinal diseases and developed as living therapeutics. We also demonstrate that the type I CRISPR-Cas system imposes a lower growth burden than the type II CRISPR-Cas system, highlighting its promising clinical application potential. Our work not only provides a new strategy for restricting the transfer of ARGs while using probiotics but also enriches the genetic engineering toolbox of EcN, paving the way for the safe use and development of probiotics as living therapeutics.

Effect of subinhibitory concentrations on the spreading of the ampicillin resistance gene blaCMY-2 in an activated sludge microcosm

ABSTRACT As the problem of multi-resistant bacteria grows a better understanding of the spread of antibiotic resistance genes is of utmost importance for society. Wastewater treatment plants contain subinhibitory concentrations of antibiotics and are thought to be hotspots for antibiotic resistance gene propagation. Here we evaluate the influence of sub-minimum inhibitory concentrations of antibiotics on the spread of resistance genes within the bacterial community in activated sludge laboratory-scale sequencing batch reactors. The mixed communities were fed two different ampicillin concentrations (500 and 5000 µg/L) and the reactors were run and monitored for 30 days. During the experiment the β-lactamase resistance gene bla CMY-2 was monitored via qPCR and DNA samples were taken to monitor the effect of ampicillin on the microbial community. The relative copy number of bla CMY-2 in the reactor fed with the sub-minimum inhibitory concentration of 500 µg/L ampicillin was spread out over a wider range of values than the control and 5000 µg/L ampicillin reactors indicating more variability of gene number in the 500 µg/L reactor. This result emphasises the problem of sub-minimum inhibitory concentrations of antibiotics in wastewater. High-throughput sequencing showed that continuous exposure to ampicillin caused a shift from a Bacteroidetes to Proteobacteria in the bacterial community. The combined use of qPCR and high-throughput sequencing showed that ampicillin stimulates the spread of resistance genes and leads to the propagation of microbial populations which are resistant to it.

Impact of copper and sulfamethazine stress on microbial community and antibiotic resistance genes in denitrification systems: Comparison between heterotrophic and sulfur autotrophic denitrification processes

As common pollutants in wastewater, heavy metals and antibiotics have negative effects on the performance, microbial community and antibiotic resistance genes (ARGs) propagation of biological treatment processes. This study investigated the differential responses of heterotrophic denitrification (HD) and sulfur autotrophic denitrification (SAD) process to Cu(II) and sulfamethazine (SMZ) stress. Exposure to 12 mg/L Cu(II) and 25 mg/L SMZ, either alone or combined, reduced nitrogen removal efficiency by 4.22 % to 32.6 % for HD and 38.7 % to 63.2 % for SAD, respectively. HD exhibited greater robustness and microbial cooperation compared to SAD under stress. Cu(II) and SMZ intensified bacterial reactive oxygen species (ROS) responses, inhibited cell activity, and reduced extracellular polymeric substance secretion. Interestingly, microbially reduced sulfides (e.g., H2S and S2−) in SAD alleviated the cellular oxidative stress induced by Cu(II) and SMZ through ROS neutralization and CuS precipitation. Under stress, the relative abundance of ARGs increased significantly more in HD than in SAD compared to their respective control groups. Network analysis revealed more potential ARGs hosts in HD than in SAD. This study underscored the potential of the microbially reduced sulfides generated in the SAD process to effectively mitigate the spread of ARGs under selective pressure from heavy metals and antibiotics.

The occurrence of banana Fusarium wilt aggravates antibiotic resistance genes dissemination in soil

The spread of antibiotic resistance genes (ARGs) and subsequent soil-borne disease outbreaks are major threats to soil health and sustainable crop production. However, the relationship between occurrences of soil-borne diseases and the transmission of soil ARGs remains unclear. Here, soil ARGs, mobile genetic elements and microbial communities from co-located disease suppressive and conducive banana orchards were deciphered using metagenomics and metatranscriptomics approaches. In total, 23 ARG types, with 399 subtypes, were detected using a metagenomics approach, whereas 23 ARG types, with 452 subtypes, were discovered using a metatranscriptomics method. Furthermore, the metagenomics analysis revealed that the ARG total abundance levels were greater in rhizospheres (0.45 ARGs/16S rRNA on average) compared with bulk (0.32 ARGs/16S rRNA on average) soils. Interestingly, metatranscriptomics revealed that the total ARG abundances were greater in disease-conducive (8.85 ARGs/16S rRNA on average) soils than disease suppressive (1.45 ARGs/16S rRNA on average) soils. Mobile genetic elements showed the same trends as ARGs. Network and binning analyses indicated that Mycobacterium, Streptomyces, and Blastomonas are the main potential hosts of ARGs. Furthermore, Bacillus was significantly and negatively correlated with Fusarium (P < 0.05, r = −0.84) and hosts of ARGs (i.e., Mycobacterium, Streptomyces, and Blastomonas). By comparing metagenomic and metatranscriptomic analyses，this study demonstrated that metatranscriptomics may be more sensitive in indicating ARGs activities in soil. Our findings enable the more accurate assessment of the transmission risk of ARGs. The data provide a new perspective for recognizing soil health, in which soil-borne disease outbreaks appear to be associated with ARG spread, whereas beneficial microbe enrichment may mitigate wilt disease and ARG transmission.

Unveiling the role of uranium in enhancing the transformation of antibiotic resistance genes

Transformation represents one of the most important pathways for the horizontal transfer of antibiotic resistance genes (ARGs), which enables competent bacteria to acquire extracellular ARGs from the surrounding environment. Both heavy metals and irradiation have been demonstrated to influence the bacterial transformation process. However, the impact of ubiquitously occurring radioactive heavy metals on the transformation of ARGs remains largely unknown. Here, we showed that a representative radioactive nuclide, uranium (U), at environmental concentrations (0.005–5 mg/L), improved the transformation frequency of resistant plasmid pUC19 into Escherichia coli by 0.10–0.85-fold in a concentration-dependent manner. The enhanced ARGs transformation ability under U stress was demonstrated to be associated with reactive oxygen species (ROS) overproduction, membrane damage, and up-regulation of genes related to DNA uptake and recombination. Membrane permeability and ROS production were the predominant direct and indirect factors affecting transformation ability, respectively. Our findings provide valuable insight into the underlying mechanisms of the impacts of U on the ARGs transformation process and highlight concerns about the exacerbated spread of ARGs in radioactive heavy metal-contaminated ecosystems, especially in areas with nuclear activity or accidents.

Effects of polypropylene microplastics on digestion performance, microbial community, and antibiotic resistance during microbial anaerobic digestion

As an emerging pollutant, microplastics (MPs) have attracted increasing attention worldwide. The effects of polypropylene (PP) MPs on digestion performance, behaviors of dominant microbial communities, antibiotic resistance genes (ARGs) and mobile genetic elements in microbial anaerobic digesters were investigated. The results showed that the addition of PP-MPs to digesters led to an increase in methane production of 10.8% when 300 particles/g TSS of PP-MPs was introduced compared with that in digester not treated with PP-MPs. This increase was attributed to the enrichment of acetogens such as Syntrophobacter (42.0%), Syntrophorhabdus (27.0%), and Syntrophomonas (10.6%), and methanogens including Methanobacterium and Methanosaeta. tetX was highly enriched due to PP-MP exposure, whereas parC exhibited the greatest increase (35.5% – 222.7%). Horizontal gene transfer via ISCR1 and intI1 genes might play an important role in the spread of ARGs. Overall, these findings provide comprehensive insight into the ecological dynamics of PP-MPs during microbial anaerobic digestion.

CRISPR-AMRtracker: A novel toolkit to monitor the antimicrobial resistance gene transfer in fecal microbiota

The spread of antibiotic resistance genes (ARGs), particularly those carried on plasmids, poses a major risk to global health. However, the extent and frequency of ARGs transfer in microbial communities among human, animal, and environmental sectors is not well understood due to a lack of effective tracking tools. We have developed a novel fluorescent tracing tool, CRISPR-AMRtracker, to study ARG transfer. It combines CRISPR/Cas9 fluorescence tagging, fluorescence-activated cell sorting, 16S rRNA gene sequencing, and microbial community analysis. CRISPR-AMRtracker integrates a fluorescent tag immediately downstream of ARGs, enabling the tracking of ARG transfer without compromising the host cell's antibiotic susceptibility, fitness, conjugation, and transposition. Notably, our experiments demonstrate that sfGFP-tagged plasmid-borne mcr-1 can transfer across diverse bacterial species within fecal samples. This innovative approach holds the potential to illuminate the dynamics of ARG dissemination and provide valuable insights to shape effective strategies in mitigating the escalating threat of antibiotic resistance.

Farm dairy effluent irrigation

Dairy intensification produces a large amount of farm dairy effluents (FDE). The final disposal of FDE is generally to the soil as fertilizer. While this use of FDE as fertilizer has numerous benefits, such as reducing the application of synthetic fertilizers or improving soil quality, there are concerns about the environmental and health risks associated with microbial pathogens from animal waste, the spread of antibiotic resistance genes, nutrient losses and greenhouse gases (GHG) emissions. Furthermore, how this agricultural practice impacts the composition and functionality of soil microbial communities has not yet been elucidated. This thesis aimed to evaluate the impact of FDE applications on soil GHG emissions, the composition, activity and diversity of its microbial community, and health risks. The FDE were collected raw and from a two-stage stabilization lagoon. The N application rate normalized to 200 kg N ha−1 was divided into four seasonal applications compared to urea fertilization or a no-aggregate control. Soil samples were taken after each application for microbial and physicochemical characterization and GHG fluxes were measured up to twenty days after each application. The pasture was harvested according to typical grazing management. Repeated application of both types of FDE increased the soil nutrient status and enhanced microbial activity. Higher fescue pasture production and macronutrient content with FDE than the control positioned FDE application to soil as an alternative disposal. However, N2O emissions increased after applying both FDE’s, most notably with raw FDE. Soil microbial community composition was not significantly influenced by FDE applications, but functional diversity shifted with raw FDE. Lagoon storage effectively reduced organic C and total N along with pathogenic indicator bacteria and changed the bacterial community composition except in winter. Beta-lactam resistance genes were detected in both FDEs, but not in the soil after repeated applications.

Pollution status and spatial distribution of antibiotic resistance genes in urban surface water and surrounding soil media

The pollution of urban rivers by antibiotic resistance genes (ARGs) is affected by the production of antibiotics and the activities of residents in the regions, posing a threat to the health of the population around the regions. A detailed investigation of the spread of ARGs in urban rivers and the surrounding soil media provides both data support and basic framework for tracking the spread and for the elimination of ARGs. In this study, real-time fluorescence quantitative PCR (qPCR) was used to investigate the contamination status and spatial distribution patterns of ARGs around the entire basin of urban river, namely the Minxin river, and the city ring water system in Shijiazhuang, China. The contamination of ARGs in midstream and downstream of the Minxin river was more severe. No obviously spatial distribution differences were found in the soil samples. Water bodies are more susceptible to human activities than soil. It was identified that sul1, sul2, and blaSHV were the dominant genes of the ARGs. Significant correlations exist between ARGs and int1 and tnpA-IS4. Mobile genetic elements (MGEs) play a key role in the horizontal gene transfer of ARGs, facilitating their spread and dispersal among different species. This work revealed the geospatial characteristics of the distribution of ARGs in urban river basins, concluding that the production and living activities could accelerate the spread and diffusion of ARGs in urban river environments, and that an attention should be given to the use control and discharge of antibiotics.

Metagenomics uncovers microbiome and resistome in soil and reindeer faeces from Ny-Ålesund (Svalbard, High Arctic)

Research on the microbiome and resistome in polar environments, such as the Arctic, is crucial for understanding the emergence and spread of antibiotic resistance genes (ARGs) in the environment. In this study, soil and reindeer faeces samples collected from Ny-Ålesund (Svalbard, High Arctic) were examined to analyze the microbiome, ARGs, and biocide/metal resistance genes (BMRGs). The dominant phyla in both soil and faeces were Pseudomonadota, Actinomycetota, and Bacteroidota. A total of 2618 predicted Open Reading Frames (ORFs) containing antibiotic resistance genes (ARGs) were detected. These ARGs belong to 162 different genes across 17 antibiotic classes, with rifamycin and multidrug resistance genes being the most prevalent. We focused on investigating antibiotic resistance mechanisms in the Ny-Ålesund environment by analyzing the resistance genes and their biological pathways. Procrustes analysis demonstrated a significant correlation between bacterial communities and ARG/BMRG profiles in soil and faeces samples. Correlation analysis revealed that Pseudomonadota contributed most to multidrug and triclosan resistance, while Actinomycetota were predominant contributors to rifamycin and aminoglycoside resistance. The geochemical factors, SiO42− and NH4+, were found to significantly influence the microbial composition and ARG distribution in the soil samples. Analysis of ARGs, BMRGs, virulence factors (VFs), and pathogens identified potential health risks associated with certain bacteria, such as Cryobacterium and Pseudomonas, due to the presence of different genetic elements. This study provided valuable insights into the molecular mechanisms and geochemical factors contributing to antibiotic resistance and enhanced our understanding of the evolution of antibiotic resistance genes in the environment.

Ketoprofen promotes the conjugative transfer of antibiotic resistance among antibiotic resistant bacteria in natural aqueous environments

The emergence and spread of antibiotic resistance in the environment pose a serious threat to global public health. It is acknowledged that non-antibiotic stresses, including disinfectants, pharmaceuticals and organic pollutants, play a crucial role in horizontal transmission of antibiotic resistance genes (ARGs). Despite the widespread presence of non-steroidal anti-inflammatory drugs (NSAIDs), notably in surface water, their contributions to the transfer of ARGs have not been systematically explored. Furthermore, previous studies have primarily concentrated on model strains to investigate whether contaminants promote the conjugative transfer of ARGs, leaving the mechanisms of ARG transmission among antibiotic resistant bacteria in natural aqueous environments under the selective pressures of non-antibiotic contaminants remains unclear. In this study, the Escherichia coli (E. coli) K12 carrying RP4 plasmid was used as the donor strain, indigenous strain Aeromonas veronii containing rifampicin resistance genes in Taihu Lake, and E. coli HB101 were used as receptor strains to establish inter-genus and intra-genus conjugative transfer systems, examining the conjugative transfer frequency under the stress of ketoprofen. The results indicated that ketoprofen accelerated the environmental spread of ARGs through several mechanisms. Ketoprofen promoted cell-to-cell contact by increasing cell surface hydrophobicity and reducing cell surface charge, thereby mitigating cell-to-cell repulsion. Furthermore, ketoprofen induced increased levels of reactive oxygen species (ROS) production, activated the DNA damage-induced response (SOS), and enhanced cell membrane permeability, facilitating ARG transmission in intra-genus and inter-genus systems. The upregulation of outer membrane proteins, oxidative stress, SOS response, mating pair formation (Mpf) system, and DNA transfer and replication (Dtr) system related genes, as well as the inhibition of global regulatory genes, all contributed to higher transfer efficiency under ketoprofen treatment. These findings served as an early warning for a comprehensive assessment of the roles of NSAIDs in the spread of antibiotic resistance in natural aqueous environments.

A metagenomics-based approach to decipher the resistome and mobilome of two seahorse species, Hippocampus barbouri and Hippocampus comes

This study aimed to explore the abundance and diversity of antibiotic resistance genes (ARGs) in seahorses (Hippocampus barbouri and Hippocampus comes) and their surrounding environment. The combination of shotgun metagenomics and bioinformatics demonstrated a higher abundance of ARGs in seahorse-associated microbiomes, particularly in skin and gut samples, compared to water and sediment. Interestingly, genes conferring multidrug resistance (e.g., acrB, acrF, cpxA, msbA, and oqxB) were highly prevalent in all samples, especially in skin and gut samples. High levels of genes conferring resistance to fluoroquinolones (e.g., mfd and emrB), β-lactam (e.g., blaCMY-71, blaOXA-55, and penA), aminocoumarin (e.g., mdtB and mdtC), and peptide antibiotics (arnA, pmrE, and rosA) were also observed in skin and gut samples. An enrichment of mobile genetic elements (MGEs) was also observed in the analyzed samples, highlighting their potential role in facilitating the acquisition and spread of ARGs. In fact, the abundance of mobilization (MOB) relaxases (e.g., MOBF, MOBP, MOBT, and MOBV) in gut and skin samples suggests a high potential for conjugation events. The occurrence of ARGs and MGEs in seahorses and the surrounding environment raises concerns about their transmission to humans, either through direct contact or the consumption of contaminated seafood. To the best of our knowledge, this study represents the first comprehensive analysis of ARGs in seahorse-associated microbiomes, and its results emphasize the need for monitoring and controlling the spread of ARGs in environmental settings.

Postbiotic as Novel Alternative Agent or Adjuvant for the Common Antibiotic Utilized in the Food Industry.

Antibiotic resistance is a serious public health problem as it causes previously manageable diseases to become deadly infections that can cause serious disability or even death. Scientists are creating novel approaches and procedures that are essential for the treatment of infections and limiting the improper use of antibiotics in an effort to counter this rising risk. With a focus on the numerous postbiotic metabolites formed from the beneficial gut microorganisms, their potential antimicrobial actions, and recent associated advancements in the food and medical areas, this review presents an overview of the emerging ways to prevent antibiotic resistance. Presently, scientific literature confirms that plant-derived antimicrobials, RNA therapy, fecal microbiota transplantation, vaccines, nanoantibiotics, haemofiltration, predatory bacteria, immunotherapeutics, quorum-sensing inhibitors, phage therapies, and probiotics can be considered natural and efficient antibiotic alternative candidates. The investigations on appropriate probiotic strains have led to the characterization of specific metabolic byproducts of probiotics named postbiotics. Based on preclinical and clinical studies, postbiotics with their unique characteristics in terms of clinical (safe origin, without the potential spread of antibiotic resistance genes, unique and multiple antimicrobial action mechanisms), technological (stability and feasibility of largescale production), and economic (low production costs) aspects can be used as a novel alternative agent or adjuvant for the common antibiotics utilized in the production of animal-based foods. Postbiotic constituents may be a new approach for utilization in the pharmaceutical and food sectors for developing therapeutic treatments. Further metabolomics investigations are required to describe novel postbiotics and clinical trials are also required to define the sufficient dose and optimum administration frequency of postbiotics.

Viral and thermal lysis facilitates transmission of antibiotic resistance genes during composting.

The spread of antibiotic resistance genes (ARGs) is a critical global health concern. Understanding the factors influencing the release of extracellular ARGs (eARGs) is essential for developing effective strategies. In this study, we investigated the association between viral lysis, heat, and eARG release during composting. Our findings revealed a substantial increase in eARGs despite reduced intracellular ARG abundance. Composting temperature and viral lysis were identified as key drivers, with thermal lysis predominant during the thermophilic phase and viral lysis during non-thermal phases. Moreover, eARGs released during composting posed a transmission risk through horizontal gene transfer. This study highlights the significance of temperature and phage lysis in ARG spread, providing valuable insights for mitigating antibiotic resistance threats.

Whatever does not kill them makes them stronger: Using quaternary ammonia antimicrobials to alleviate the inhibition of ammonia oxidation under perfluorooctanoic acid stress

Perfluorooctanoic acid (PFOA), benzalkyl dimethylammonium compounds (BAC) and antibiotic resistance genes (ARGs) have negative effects on biological sewage treatment. The performance of nitrification systems under stress of PFOA (0.1–5 mg/L) or/and BAC (0.2–10 mg/L) was explored during 84-day experiments using four sequencing batch reactors, in this study. Low (0.1 mg/L) concentration PFOA had a positive influence on ammonia removal, while medium and high (2 and 5 mg/L) concentrations PFOA caused severe inhibition. Meanwhile, PFOA stress resulted in the enrichment of ARGs in water (w-ARGs). BAC (0–10 mg/L) had no obvious influence on ammonia removal. However, BAC promoted the reduction of ARGs and the bacterial community was the main participator (48.07%) for the spread of ARGs. Interestingly, the joint stress of PFOA and BAC increased the ammonia-oxidizing bacteria (AOB) activity from 5.81 ± 0.19 and 6.05 ± 0.79 mg N/(g MLSS·h) to 7.09 ± 0.87 and 7.23 ± 0.29 mg N/(g MLSS·h) in medium and high concentrations, compared to single stress of PFOA, which was observed for the first time. BAC could reduce bioavailability of PFOA through competitive adsorption and decreasing sludge hydrophobicity by the lower β-Sheet and α-Helix in tightly bound protein. Furthermore, the joint stress of PFOA and BAC was able to intensify the proliferation of w-ARGs and extracellular ARGs in sludge, and developed the most active horizontal gene transfer mediated by intl1 compared to single stress of PFOA or BAC. The batch tests verified the detoxification capacity of BAC on nitrification under 2.5 mg/L PFOA (48 h exposing), and the maximum alleviation of AOB activity was achieved at BAC and PFOA mass ratio of 2:1. In summary, BAC could be used to alleviate the inhibition of PFOA on ammonia oxidation, providing an efficient and sustainable approach in wastewater treatment.

Aerosol-Mediated Spread of Antibiotic Resistance Genes: Biomonitoring Indoor and Outdoor Environments.

Antimicrobial resistance (AMR) has emerged as a conspicuous global public health threat. The World Health Organization (WHO) has launched the "One-Health" approach, which encourages the assessment of antibiotic resistance genes (ARGs) within an environment to constrain and alleviate the development of AMR. The prolonged use and overuse of antibiotics in treating human and veterinary illnesses, and the inability of wastewater treatment plants to remove them have resulted in elevated concentrations of these metabolites in the surroundings. Microbes residing within these settings acquire resistance under selective pressure and circulate between the air-land interface. Initial evidence on the indoor environments of wastewater treatment plants, hospitals, and livestock-rearing facilities as channels of AMR has been documented. Long- and short-range transport in a downwind direction disseminate aerosols within urban communities. Inhalation of such aerosols poses a considerable occupational and public health risk. The horizontal gene transfer (HGT) is another plausible route of AMR spread. The characterization of ARGs in the atmosphere therefore calls for cutting-edge research. In the present review, we provide a succinct summary of the studies that demonstrated aerosols as a media of AMR transport in the atmosphere, strengthening the need to biomonitor these pernicious pollutants. This review will be a useful resource for environmental researchers, healthcare practitioners, and policymakers to issue related health advisories.

Evolution and distribution of antibiotic resistance genes in submerged macrophytes and biofilm systems: From seasonal monitoring to mesocosm experiments

The aquatic ecosystem has been extensively investigated as a hotspot for the spread of antibiotic resistance genes (ARGs); yet, the evolution and distribution of ARGs profiles in submerged macrophytes biofilms and surrounding water remained unclear. In this study, the dynamic distribution and seasonal variations of microbial communities and ARGs profiles were investigated, alongside their assembly processes and mutual interactions. Bacitracin and multidrug resistance genes were predominant, constituting more than 60% of the total ARGs abundance. The deterministic processes (<65%), influenced by the physicochemical properties of the river environment, governed the assembly and composition of ARGs profiles, exhibiting significant seasonal variation. The peak diversity (21 types) and abundance (0.316 copy ratios) of ARGs were detected during the summer. Proteobacteria and Actinobacteria were the dominant bacterial phyla, accounting for 38.41–85.50% and 4.03–27.09% of the microbial community, respectively. Furthermore, Proteobacteria, especially genera such as Acinetobacter, Burkholderia, and Pseudomonas, with various resistance sequences, were the primary carriers of multiple ARGs. Notably, the genetic exchanges between biofilms and surrounding water facilitated the further propagation of high-risk ARGs, posing greater ecological risks. Redundancy analysis indicated that the total nitrogen and temperature in water determined the fate of pathogenic-resistant species. These findings provided theoretical support for the mitigation of ARGs contamination in aquatic environments.

Horizontal 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.