Antimicrobials and antimicrobial resistance genes in the shadow of COVID-19 pandemic: A wastewater-based epidemiology perspective.

Higher usage of antimicrobial agents in both healthcare facilities and the communities has resulted in an increased spread of resistant bacteria. However, the improved infection prevention and control practices may also contribute to decreasing antimicrobial resistance (AMR). In the present study, wastewater-based epidemiology (WBE) approach was applied to explore the link between COVID-19 and the community usage of antimicrobials, as well as the prevalence of resistance genes. Longitudinal study has been conducted to monitor the levels of 50 antimicrobial agents (AAs), 24 metabolites, 5 antibiotic resistance genes (ARGs) and class 1 integrons (intI 1) in wastewater influents in 4 towns/cities over two years (April 2020 - March 2022) in the South-West of England (a total of 1,180 samples collected with 87,320 individual AA measurements and 8,148 ARG measurements). Results suggested higher loads of AAs and ARGs in 2021-22 than 2020-21, with beta-lactams, quinolones, macrolides and most ARGs showing statistical differences. In particular, the intI 1 gene (a proxy of environmental ARG pollution) showed a significant increase after the ease of the third national lockdown in England. Positive correlations for all quantifiable parent AAs and metabolites were observed, and consumption vs direct disposal of unused AAs has been identified via WBE. This work can help establish baselines for AMR status in communities, providing community-wide surveillance and evidence for informing public health interventions. Overall, studies focused on AMR from the start of the pandemic to the present, especially in the context of environmental settings, are of great importance to further understand the long-term impact of the pandemic on AMR.

Understanding treatment of pain during SARS-CoV-2 pandemic in a two-year intercity longitudinal study using wastewater-based epidemiology.

SARS-CoV-2 pandemic had a significant impact on the society, economy, and health of people around the world with consequences that need to be better understood for future pandemic preparedness. This manuscript provides insights into the usage of pharmaceuticals for pain treatment management throughout SARS-CoV-2 pandemic. Four towns and cities with a total population of > 1 million people covering an area of 2000 km2 in South West England were monitored for twenty-four months. Results showed different patterns in pain pharma usage, with small towns having higher population normalised daily loads (PNDLs) than big cities for majority of pain killers studied. This is likely due to demographics of these cities with smaller cities having older population. Per capita consumption of non-steroidal anti-inflammatory drugs (NSAIDs) increased compared to pre-pandemic usage in line with SARS-CoV-2 infections (ibuprofen and acetaminophen), while body pain drugs (diclofenac and naproxen) decreased in line with restrictions and closure of sports facilities. Changes in population normalised daily intake (PNDI) of pain killers were particularly apparent during the 1st and 3rd national lockdown. Comparison of PNDIs with prescriptions highlighted differences related to medication availability (OTC drugs) and patients' nonadherence (prescribed drugs). In addition, several instances of direct disposal events across the catchments were observed which raises an issue of lack of pharma compliance and general understanding of potential environmental impacts from pharma usage.

Assessment of restriction measures implemented during COVID pandemics on community lifestyle choices via wastewater-based epidemiology.

SARS-CoV-2 pandemic affected lifestyle habits, and the mental health and wellbeing of people around the world. In this manuscript, two towns (Paulton and Radstock) and two cities (Bath and Bristol) in Southwest England (> 1 million people) were monitored for two years using Wastewater-Based Epidemiology to assess impacts of COVID (including management measures such as lockdowns and movement restrictions) on community lifestyle choices: illicit drugs, legal stimulants, abused pharmaceuticals and pain pharma usage. Results were triangulated with key dates captured during the pandemic (national lockdowns, restrictions and social distancing measures, etc.). This highlighted a reduction in cocaine intake (as benzoylecgonine) (community average: -36 %) during the first lockdown and an increase in illicit drugs usage after the 3rd national lockdown (community averages for amphetamine: +8 %, cocaine/benzoylecgonine: +39 %, ketamine:+70 %) when restrictions were removed, and social interaction and recreational activities increased. There was a reduction in the intake of caffeine (as 1,7-dimethylxanthine) (community average:-39 %) after 3rd national lockdown coinciding with pubs reopening while nicotine intake (via cotinine) remained stable indicating lack of impact of COVID on smoking habits. Pain pharma often used in pain management resulting from injuries linked with sport activities (naproxen and diclofenac) showed decrease in usage due to lockdown restrictions in physical exercise and access to gyms/sport facilities.

Understanding associations between antimicrobial agents usage and antimicrobial resistance genes prevalence at the community level using wastewater-based epidemiology: A Spanish pilot study.

Understanding the development and spread of antimicrobial resistance (AMR) is important for combating this global threat for public health. Wastewater-based epidemiology (WBE) is a complementary approach to current surveillance programs that minimizes some of the existing limitations. The aim of the present study is to explore WBE for monitoring antibiotics and antibiotic resistance genes (ARGs) in wastewater samples collected during 2021/2022 from the city of Castellon (Spain). Eighteen commonly prescribed antibiotics have been selected and measured by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), with triple quadrupole mass analysers. Moreover, qPCR for specific ARGs has been performed to obtain information of these genes in co-presence with antibiotics. All selected ARGs, along with a total of 11 antibiotics, were identified. The highest population-normalized daily loads were observed for the macrolide azithromycin, followed by the quinolones ciprofloxacin and levofloxacin. Subsequently, daily consumption estimates based on wastewater data were compared with prescription data of antibiotics. Statistical analyses were conducted to explore if there is correlation between antibiotics and ARGs. While no correlations were found between antibiotics and their corresponding ARGs, certain correlations (p < 0.05) were identified among non-corresponding ARGs. In addition, a strong positive correlation was found between the sum of all antibiotics and the intl1 gene. Moreover, population-normalized ARG loads significantly correlate with the 16S rRNA-normalized ARG loads, serving as an indicator for population size. Results provide a baseline for future work and a proof-of-concept emphasising the need for future work and long-term surveillance, and highlight the need of similar programs at a regional and global levels worldwide.

Deciphering the synergistic effects of photolysis and biofiltration to actuate elimination of estrogens in natural water matrix.

The presence of estrogens in water environments has raised concerns for human health and ecosystems balance. These substances possess potent estrogenic properties, causing severe disruptions in endocrine systems and leading to reproductive and developmental problems. Unfortunately, conventional treatment methods struggle to effectively remove estrogens and mitigate their effects, necessitating technological innovation. This study investigates the effectiveness of a novel sequential photolysis-granular activated carbon (GAC) sandwich biofiltration (GSBF) system in removing estrogens (E1, E2, E3, and EE2) and improving general water quality parameters. The results indicate that combining photolysis pre-treatment with GSBF consistently achieved satisfactory performance in terms of turbidity, dissolved organic carbon (DOC), UV254, and microbial reduction, with over 77.5 %, 80.2 %, 89.7 %, and 92 % reduction, respectively. Furthermore, this approach effectively controlled the growth of microbial biomass under UV irradiation, preventing excessive head loss. To assess estrogen removal, liquid chromatography-tandem mass spectrometry (LC-MS) measured their concentrations, while bioassays determined estrogenicity. The findings demonstrate that GSBF systems, with and without photolysis installation, achieved over 96.2 % removal for estrogens when the spike concentration of each targeted compound was 10 µg L-1, successfully reducing estrogenicity (EA/EA0) to levels below 0.05. Additionally, the study evaluated the impact of different thicknesses of GAC layer filling (8 cm, 16 cm, and 24 cm) and found no significant difference (p>0.05) in estrogen and estrogenicity removal among them.

Antibiotic resistance genes and the association with bacterial community in biofilms occurring during the drinking water granular activated carbon (GAC) sandwich biofiltration.

The granular activated carbon (GAC) sandwich modification to slow sand filtration could be considered as a promising technology for improved drinking water quality. Biofilms developed on sand and GAC surfaces are expected to show a functional diversity during the biofiltration. Bench-scale GAC sandwich biofilters were set-up and run continuously with and without antibiotic exposure. Surface sand (the schmutzdecke) and GAC biofilms were sampled and subject to high-throughput qPCR for antibiotic resistance gene (ARG) analysis and 16 S rRNA amplicon sequencing. Similar diversity of ARG profile was found in both types of biofilms, suggesting that all ARG categories decreased in richness along the filter bed. In general, surface sand biofilm remained the most active layer with regards to the richness and abundance of ARGs, where GAC biofilms showed slightly lower ARG risks. Network analysis suggested that 10 taxonomic genera were implicated as possible ARG hosts, among which Nitrospira, Methyloversatilis and Methylotenera showed the highest correlation. Overall, this study was the first attempt to consider the whole structure of the GAC sandwich biofilter and results from this study could help to further understand the persistence of ARGs and their association with the microbial community in drinking water biofiltration system.

Assessment of the stability of antimicrobials and resistance genes during short- and long-term storage condition: accounting for uncertainties in bioanalytical workflows.

Unravelling complexities in antimicrobial agent-microbe interactions in the context of antimicrobial resistance (AMR) requires robust analytical workflows accounting for all uncertainties. Temporal storage of wastewater samples under refrigerated or frozen conditions prior to chemical and biological analysis is widely used to facilitate laboratory routine but may affect stability of analytes over time. Yet, little knowledge exists regarding stability of biological and chemical determinants in environmental samples, which hampers validity of research outputs. This study examines, for the first time, the stability of 32 antimicrobials (AAs) including commonly used classes of antibiotics and their representative metabolites and variation of 5 antibiotic resistance genes (ARGs) (ermB, sul1, tetW, blaCTX-M, qnrS), as well as intI1 and 16S rRNA genes in a reference wastewater sample stored under freezing condition for up to 1 year. Ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) and quantitative PCR (qPCR) techniques were adopted to measure concentration of AAs and ARGs, respectively. Results suggested that parent compounds are less affected by freezing storage compared to the metabolites. ß-Lactams, clindamycin, and N-desmethyl clindamycin are the most-affected compounds which were poorly recovered (34-67%) from the starting concentration. By contrast, sulfonamides, macrolides, quinolones, and azoles are generally stable under freezing condition. No consistent differences were observed in gene copies between fresh and frozen samples, and ermB and tetW showed the highest variabilities at 30% under freezing condition. Overall, this study adds to the current knowledge on environmental AMR monitoring and emphasises the need for standardised protocols for AMR monitoring in the wastewater samples.

[Chemical constituents from Pulsatillae Radix].

Chemical constituents of ethanol extract of Pulsatillae Radix were investigated. The n-butanol fraction of ethanol extract of Pulsatillae Radix was isolated and purified by macroporous resin and silica gel column chromatography and semi-preparative high performance liquid chromatography. The triterpenoid glycosides were identified by multiple spectral methods. Six compounds were obtained from the n-butanol fraction of ethanol extract of Pulsatillae Radix and identified as 23-aldehyde-cussosaponin C(1), cussosaponin C(2), anemoside B4(3), akebia saponin D(4), pulchinenoside E3(5), and hederacoside C(6). Among them, compound 1 was a new compound.

Fast-charging aluminium-chalcogen batteries resistant to dendritic shorting.

Although batteries fitted with a metal negative electrode are attractive for their higher energy density and lower complexity, the latter making them more easily recyclable, the threat of cell shorting by dendrites has stalled deployment of the technology1,2. Here we disclose a bidirectional, rapidly charging aluminium-chalcogen battery operating with a molten-salt electrolyte composed of NaCl-KCl-AlCl3. Formulated with high levels of AlCl3, these chloroaluminate melts contain catenated AlnCl3n+1- species, for example, Al2Cl7-, Al3Cl10- and Al4Cl13-, which with their Al-Cl-Al linkages confer facile Al3+ desolvation kinetics resulting in high faradaic exchange currents, to form the foundation for high-rate charging of the battery. This chemistry is distinguished from other aluminium batteries in the choice of a positive elemental-chalcogen electrode as opposed to various low-capacity compound formulations3-6, and in the choice of a molten-salt electrolyte as opposed to room-temperature ionic liquids that induce high polarization7-12. We show that the multi-step conversion pathway between aluminium and chalcogen allows rapid charging at up to 200C, and the battery endures hundreds of cycles at very high charging rates without aluminium dendrite formation. Importantly for scalability, the cell-level cost of the aluminium-sulfur battery is projected to be less than one-sixth that of current lithium-ion technologies. Composed of earth-abundant elements that can be ethically sourced and operated at moderately elevated temperatures just above the boiling point of water, this chemistry has all the requisites of a low-cost, rechargeable, fire-resistant, recyclable battery.

Assessment of community-wide antimicrobials usage in Eastern China using wastewater-based epidemiology.

Wastewater-based epidemiology (WBE) has potential to identify the epidemiological links between people, animals, and the environment, as part of antimicrobial resistance (AMR) surveillance. In this study, we investigated six wastewater treatment plants (WWTPs) serving six communities located in two regions in Eastern China: Site A in Zhejiang and site B in Jiangsu province to assess the public use of antimicrobial agents (AA). Fifty antimicrobials and 24 of their metabolites were quantified using ultraperformance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UPLC-MS/MS). Spatiotemporal trends were established for measured concentrations, daily loads, and population-normalised daily loads. Daily AA mass loads varied between 1.6 g/day and 324.6 g/day reflecting the WWTP scales, with macrolides and ß-lactams showing the highest overall environmental burden at 223.7 g/day and 173.7 g/day, respectively. Emissions of antibiotic residues from manufacturing have been observed, with the peak daily load 12-fold higher than the overall load from a community serving a population of over 600,000. Community exposure levels of 225.2 ± 156.2 mg/day/1000 inhabitant and 351.9 ± 133.5 mg/day/1000 inhabitant were recorded in site A and B, respectively. Paired parent-metabolites analysis identified a large proportion (64-78%) of un-metabolised metronidazole and clindamycin at site B, indicating improper disposal of unused drugs either in the community or in livestock production. Consumption levels, calculated via WBE, suggested relatively low antimicrobial usage in Eastern China compared to other areas in China. This first application of WBE in Eastern China to assess the community-wide exposure to AAs has potential to inform regional antimicrobial stewardship.

Impacts of Antibiotic Residues in the Environment on Bacterial Resistance and Human Health in Eastern China: An Interdisciplinary Mixed-Methods Study Protocol.

Antibiotic resistance is a global health challenge that threatens human and animal lives, especially among low-income and vulnerable populations in less-developed countries. Its multi-factorial nature requires integrated studies on antibiotics and resistant bacteria in humans, animals, and the environment. To achieve a comprehensive understanding of the situation and management of antibiotic use and environmental transmission, this paper describes a study protocol to document human exposure to antibiotics from major direct and indirect sources, and its potential health outcomes. Our mixed-methods approach addresses both microbiological and pathogen genomics, and epidemiological, geospatial, anthropological, and sociological aspects. Implemented in two rural residential areas in two provinces in Eastern China, linked sub-studies assess antibiotic exposure in population cohorts through household surveys, medicine diaries, and biological sampling; identify the types and frequencies of antibiotic resistance genes in humans and food-stock animals; quantify the presence of antibiotic residues and antibiotic resistance genes in the aquatic environment, including wastewater; investigate the drivers and behaviours associated with human and livestock antibiotic use; and analyse the national and local policy context, to propose strategies and systematic measurements for optimising and monitoring antibiotic use. As a multidisciplinary collaboration between institutions in the UK and China, this study will provide an in-depth understanding of the influencing factors and allow comprehensive awareness of the complexity of AMR and antibiotic use in rural Eastern China.

Mechanisms underlying the effect of chlorination and UV disinfection on VBNC state Escherichia coli isolated from hospital wastewater.

The occurrence of viable but non-culturable (VBNC) bacteria in the wastewater system poses a huge threat to environmental and public health, in particular in hospital wastewater treatment system (HWTS). HWTS-oriented studies have been conducted to assess the effectiveness of chlorination and UV disinfection using indigenous bacteria. Results revealed that the VBNC Escherichia coli and ARGs remained persistent even at high chlorination (12 mg/L for 2.5 h) and UV doses (1000 mJ/cm2). The molecular mechanisms underlying chlorination-/UV-induced VBNC state in E. coli were explored through the transcriptomics and results suggested that most energy-dependent physiological activities (e.g., metabolism) have been suppressed in VBNC E. coli, while the pathogenicity-related genes varied insignificantly compared to the culturable cells, indicating that the VBNC E. coli could potentially display pathogenicity. Further Galleria mellonella model experiment has confirmed that although the disinfection-induced VBNC state made cells less infectious, these cells could regain their pathogenicity after resuscitation. This in vitro study can be used as a reference for studies on infections from VBNC bacteria and highlights the health risk due to VBNC pathogens in hospital effluents. There is a need to develop effluent standards specifically for healthcare facilities, and a stricter downstream disinfection strategy should be considered for the removal of VBNC cells and ARGs in the effluent.

Removal of antibiotics in sand, GAC, GAC sandwich and anthracite/sand biofiltration systems.

Drinking water biofiltration offers the possibility of the removal of trace level micropollutants from source water. Sand, granular activated carbon (GAC), GAC sandwich (a layer of GAC loaded in the middle of sand bed), and anthracite-sand dual biofilters were set-up in duplicate at bench-scale to mimic the filtration process in real drinking water treatment works. During the 3-month system operation, removal of five antibiotics (amoxicillin, clarithromycin, oxytetracycline, sulfamethoxazole, and trimethoprim) and overall biofilter performance were evaluated. Natural surface water spiked with a mixture of the target antibiotics was used as feedwater to the biofilters. Results showed that the target antibiotics were substantially removed (>90%) by GAC-associated biofilters and partially removed (≤20%) by sand alone and anthracite-sand biofilters. In particular, the GAC sandwich biofilter exhibited superior performance compared to sand/anthracite biofilter, and the comparisons among all biofilters indicated that both adsorption and biodegradation contributed to the removal of the target antibiotics in the GAC-associated biofilters. Adsorption kinetics showed that sulfamethoxazole fitted with pseudo-first-order adsorption model, while trimethoprim, amoxicillin, oxytetracycline and clarithromycin fitted the pseudo-second-order model. All antibiotics fitted the Langmuir model according to the isotherm experiment. To date, this is the first study evaluating the removal of antibiotics by GAC sandwich biofilters. Overall, this research will provide useful information which can be used for optimising or updating existing biofiltration processes in industry to reduce antibiotic residues from source water.

Microbiological safety and antibiotic resistance risks at a sustainable farm under large-scale open-air composting and composting toilet systems.

This study evaluated the microbial safety and antibiotic resistance risks of a sustainable ecological farm under large-scale open-air composting (OC) and green composting toilet systems (CT). Samples of livestock manure, compost, soil, vegetables, and rainwater were analysed to determine the best treatment of wastes and risk assessment of land application. Results showed that pathogenic bacteria (PB) in livestock manure was significantly greater than that in the surrounding topsoil, while the distribution of bacteria resistant to amoxicillin (AMX), tetracycline (TC), and amoxicillin-tetracycline (AMX- TC) was the opposite through long-term resistance selection pressure. E. coli and Enterococcus were the dominant pathogens in feces and surrounding soil, respectively, and AMX-resistant bacteria dominated soil, compost, and vegetable samples. Overall, while OC may significantly increase antibiotic resistance and effectively remove fecal PB, CT offers faster consumption with greater antibiotic resistant bacteria (ARB) removal but more PB. Moreover, PB and ARB were concentrated in mature compost, soil in planting areas, vegetables, and rainwater. In farm soil and vegetables, AMX-resistant and AMX-TC-resistant bacterial communities displayed similar composition. These findings may explain the main pathways of PB transmission, migration and accumulation of ARB in farms, and the potential risks to human health through the food chain.

Drinking water biofiltration: Behaviour of antibiotic resistance genes and the association with bacterial community.

Antibiotic resistance genes (ARGs) are being detected in drinking water frequently, constituting a major public health issue. As a typical drinking water treatment process, the biofilter may harbour various ARGs due to the filter biofilms established during the filtration process. The objective of this study was to investigate the behaviour of ARGs (blaCTX-M, blaOXA-1, blaTEM, ermB, tetA, tetG, tetQ, tetW, tetX, sul 1, sul 2, dfrA1 and dfrA12) and their possible association with bacteria in a bench-scale biofiltration system. The impact of filter media on horizontal gene transfer (HGT) was also explored using a model conjugative plasmid, RP1. The biofiltration system comprised four types of biofilters, including sand, granular activated carbon (GAC), GAC sandwich, and anthracite-sand biofilters. Results showed that although the absolute abundance of ARGs decreased (0.97-log reduction on average), the ARGs' abundance normalised to bacterial numbers showed an increasing trend in the filtered water. Biofilms collected from the surface layer revealed the lowest relative abundance of ARGs (p < 0.01) compared to the deeper layer biofilms, indicating that the proportion of ARG-carrying bacteria was greater in the lower position. Most chosen ARG numbers correlated to Proteobacteria, Acidobacteria and Nitrospirae phyla, which accounted for 51.9%, 5.2% and 2.0% of the biofilm communities, respectively. GAC media revealed the highest transfer frequency (2.60 × 10-5), followed by anthracite (5.31 × 10-6) and sand (2.47 × 10-6). Backwashing can reduce the transferability of RP1 plasmid significantly in biofilms but introduces more transconjugants into the planktonic phase. Overall, the results of this study could enhance our understanding of the prevalence of ARGs in drinking water biofiltration treatment.

Use of synthesized double-stranded gene fragments as qPCR standards for the quantification of antibiotic resistance genes.

Pollution of various environmental matrices by antibiotic resistance genes (ARGs) has become a growing threat to human health. For the quantitative analysis of the presence of ARGs, there is a need for sensitive and robust qPCR assays which can detect various genes from different types of DNA extracts. Fourteen ARGs were selected as target genes in this study including: blaTEM, blaOXA-1 and blaCTX-M coded for resistance to ß-lactams; ermB for macrolides; tetA, tetG, tetM, tetQ, tetW and tetX for tetracyclines; sul I and sul II for sulfonamides; drfA1 and drfA12 d for trimethoprim; and integron gene intI 1 and intI 2. Chemically synthesized double-stranded gene fragments were modified using molecular biology methods and used as real-time PCR standards as well as to establish in-house qPCR assays. The ermB gene from a naturally occurring plasmid was used to compare the performance of qPCR assay with the chemically synthesized ermB. Additionally, environmental water, soil and faeces samples were used to validate the established qPCR assays. Importantly, the study proves the usefulness of rapidly synthesized oligonucleotides serving as qPCR standards for ARG analysis and provides comparable sensitivity and reliability to a traditional amplicon standard.

Trivalent ion mediated abnormal growth of all-inorganic perovskite nanocrystals and their divergent emission properties.

In this work, a new trivalent ion-mediated one-pot synthetic protocol is reported to create two well-defined optical absorbance and photoluminescence (PL) emissions in all-inorganic halide perovskite nanocrystals (NCs). The foreign M3+ cations (M = Bi, Al, In), typically from BiBr3, BiFeO3, BiCl3, AlBr3 or InBr3, function as capping ligands for generating a growth-constrained thinner nanoplatelet (NPL) population displaying the quantum confinement effect. The formation mechanism of the growth-constrained NPLs is proposed based on density functional theory (DFT) on the different slab energy of the representative NPLs achieved in the presence of Bi3+ ions and the density of states (DOS) of the supposed bulk perovskites. Notably, the formation of two groups of NCs with different sizes allows for the generation of dual optical absorbance and PL emissions. The influence of the M : Pb molar ratios on the precursors is systematically elucidated, from which the relative intensity and position of each PL emission can be fine-tuned. By virtue of the representative NPLs with well-defined green and blue emissions, the M3+-assisted synthetic protocol provides a facile and cost-effective route for producing unique NCs and nanostructures for optoelectronic device applications.

Prevalence of bacterial resistance within an eco-agricultural system in Hangzhou, China.

The wide use of antibiotics in the animal husbandry and the relevant sustainable industries may promote the emergence of antibiotic-resistant bacteria (ARB), which constitutes a growing threat to human health. The objective of this study was to determine the abundance and diversity of sulfonamide- and tetracycline-resistant bacteria within an eco-agricultural system (EAS) in Hangzhou, China. We investigated samples at every link in the EAS, from livestock manure, to biogas residues and biogas slurry, to vegetable and ryegrass fields, to a fish pond. A combination of culture-based and 16S rRNA gene-based sequencing method was used in this study. Within the studied system, the average rate of bacterial resistance to sulfonamide (46.19 %) was much higher than that of tetracycline (8.51 %) (p < 0.01). There were 224 isolates that were enumerated and sequenced, 108 of which were identified to species level. The genera comprising the sulfamethoxazole-resistant (SMXr) bacteria were generally different from those of tetracycline-resistant (TCr) bacteria. Staphylococcus and Acinetobacter were the most dominant genera of SMXr bacteria (19.30 % of the total resistant bacteria) and TCr bacteria (14.04 % of the total resistant bacteria), respectively. Several strains of resistant opportunistic pathogens (e.g., Pantoea agglomerans) were detected in edible vegetable samples, which may exert a potential threat to both pig production and human health. In general, this study indicates that the EAS is an important reservoir of antibiotic-resistant bacteria, some of which may be pathogenic.

High-throughput profiling of antibiotic resistance genes in drinking water treatment plants and distribution systems.

Antibiotic resistance genes (ARGs) are present in surface water and often cannot be completely eliminated by drinking water treatment plants (DWTPs). Improper elimination of the ARG-harboring microorganisms contaminates the water supply and would lead to animal and human disease. Therefore, it is of utmost importance to determine the most effective ways by which DWTPs can eliminate ARGs. Here, we tested water samples from two DWTPs and distribution systems and detected the presence of 285 ARGs, 8 transposases, and intI-1 by utilizing high-throughput qPCR. The prevalence of ARGs differed in the two DWTPs, one of which employed conventional water treatments while the other had advanced treatment processes. The relative abundance of ARGs increased significantly after the treatment with biological activated carbon (BAC), raising the number of detected ARGs from 76 to 150. Furthermore, the final chlorination step enhanced the relative abundance of ARGs in the finished water generated from both DWTPs. The total enrichment of ARGs varied from 6.4-to 109.2-fold in tap water compared to finished water, among which beta-lactam resistance genes displayed the highest enrichment. Six transposase genes were detected in tap water samples, with the transposase gene TnpA-04 showing the greatest enrichment (up to 124.9-fold). We observed significant positive correlations between ARGs and mobile genetic elements (MGEs) during the distribution systems, indicating that transposases and intI-1 may contribute to antibiotic resistance in drinking water. To our knowledge, this is the first study to investigate the diversity and abundance of ARGs in drinking water treatment systems utilizing high-throughput qPCR techniques in China.

Behavior of antibiotics and antibiotic resistance genes in eco-agricultural system: A case study.

This study aims to determine abundance and persistence of antibiotics and antibiotic resistance genes (ARGs) in eco-agricultural system (EAS), which starts from swine feces to anaerobic digestion products, then application of anaerobic digestion solid residue (ADSR) and anaerobic digestion liquid residue (ADLR) to the soil to grow ryegrass, one of swine feed. Oxytetracycline had the highest concentration in manure reaching up to 138.7 mg/kg. Most of antibiotics could be effectively eliminated by anaerobic digestion and removal rates ranged from 11% to 86%. ARGs abundance fluctuated within EAS. TetQ had the highest relative abundance and the relative abundance of tetG had the least variation within the system, which indicates that tetG is persistent in the agricultural environment and requires more attention. Compared to the relative abundance in manure, tetC and tetM increased in biogas residue while three ribosomal protection proteins genes (tetO, tetQ, tetW) decreased (p<0.05), with other genes showing no significant change after anaerobic fermentation (p>0.05). Most ARGs in downstream components (soils and fishpond) of EAS showed significantly higher relative abundance than the control agricultural system (p<0.05), except for tetG and sulI.