Multiresidue antibiotic-metabolite quantification method using ultra-performance liquid chromatography coupled with tandem mass spectrometry for environmental and public exposure estimation

Realising a global One Health disease surveillance approach: insights from wastewater and beyond

One Health is a recognition of the shared environment inhabited by humans, animals and plants, and the impact of their interactions on the health of all organisms. The COVID-19 pandemic highlighted the need for a framework of pathogen surveillance in a tractable One Health paradigm to allow timely detection and response to threats to human and animal health. We present case studies centered around the recent global approach to tackle antimicrobial resistance and the current interest in wastewater testing, with the concept of "one sample many analyses" to be further explored as the most appropriate means of initiating this endeavor.

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.

Novel, alternative analytical methodology for determination of antimicrobial chemicals in aquatic environments and public use assessment: Extraction sorbent, microbiological sensitivity, stability, and applicability

BACKGROUND

Assessing antimicrobial chemicals from wastewater source to recipient water systems is crucial in planning effective, policy-related interventions for antimicrobial resistance (AMR) risk mitigation. However, the capability of related analytical methods for AMR assessment has not been explored previously. There is also a lack of knowledge on the effectiveness of alternative extraction sorbents with ion-exchange functions, and little information on chemical stability from sampling to analysis as well as preservative options. Hence, our study aims to address the clear need for advanced, broad-range and microbiologically-sensitive methodologies, paired with thorough stability assessments.

RESULTS

Oasis® WCX ion-exchange was for the first time employed in solid-phase extraction (SPE) for antibacterials, antifungals, antivirals and human metabolites in various water matrices. Analysis was performed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) on a biphenyl analytical column. The optimized and validated method provided satisfactory accuracy, precision, and recovery for 53 compounds via LC-MS/MS direct injection and for up to 35 compounds via SPE-LC-MS/MS. Method quantification limits (MQLs) were determined in groundwater (0.33-54 ng L-1), surface water (0.53-75 ng L-1), effluent wastewater (2.5-470 ng L-1), and influent wastewater (11-650 ng L-1). As a novel approach, MQLs were compared with minimum inhibitory concentrations, to confirm our method's microbiological sensitivity for studying AMR. Stability assessment revealed that most compounds remained stable in standard solution at -80 °C for six months, in various waters at -20 °C for eight weeks, and during 24-h sampling at 4 °C. Sodium azide was a better preservative than sodium metabisulfite.

SIGNIFICANCE

Our study is an added value to the analytical methodology for water measurements of antimicrobial chemicals, in which it provides a novel, alternative method that is robust and overall more sensitive than others using generic Oasis® HLB sorbents and C18 analytical columns in SPE-LC-MS/MS. Also, the comprehensive data on antimicrobial stability helps reduce methodological uncertainty for future studies. Our method shows sufficient microbiologically-sensitivity and thus is suitable for future (inter)national regulatory water monitoring of AMR.

A new Wastewater-Based Epidemiology workflow to estimate community wide non-communicable disease prevalence using pharmaceutical proxy data

This manuscript introduces a new wastewater-based epidemiology workflow for estimation of non-communicable diseases (NCDs) prevalence by using wastewater-based epidemiology (WBE) and pharmaceuticals/their metabolites as proxies for NCDs prevalence. 83 targets were selected (54 parent pharmaceuticals and 29 metabolites). Three critical aspects were tested: (i) Solid-Phase Extraction - Ultra-Performance Liquid Chromatography and Tandem Mass Spectrometry (SPE-UHPLC-MS/MS) method performance, (ii) biomarker stability under variable storage conditions (during sampling and long-term storage) and (iii) accounting for human metabolism in WBE back-calculations. High stability of most analytes was observed under tested storage conditions. A few exceptions include diazepam, dihydroketoprofen and 5-hydroxy-lansoprazole. Analyte recoveries varied between 75% and 125% for most analytes. MDLs ranged from 0.2 ng L-1 to 5.6 ng L-1, while MQLs from 0.2 ng L-1 to 16.8 ng L-1. The overall average method accuracy and precision were: 99.5% and 4.0% respectively. A fully validated method was tested using community wastewater in the Southwest of England to estimate pharmaceutical usage, test metabolism correction factors established and compare results with prescription data. The new WBE method for NCD approximation allowed for the estimation of the daily usage/intake of 69 NCD targets with a standardized approach and a consistent reporting format.

An integrated One Health framework for holistic evaluation of risks from antifungal agents in a large-scale multi-city study

A new framework for retrospective mass spectral data mining for antifungal agents (AFs) and Wastewater-Based Epidemiology (WBE) was developed as part of One Health framework to tackle risks from AFs. A large scale, multi-city study was undertaken in South-West England. Key drivers of AFs in the catchment were identified with communal wastewater discharges being the main driver for human AFs (fluconazole, ketoconazole) and agricultural runoff being the main driver for pesticide AFs (prochloraz, prothioconazole and tebuconazole). Average WBE-estimated human used fluconazole and ketoconazole PNDIs (population normalised daily intake) exceeded 300 mg day-1 1000 inh-1 and 2000 mg day-1 1000 inh-1. This is much higher than PNDPs (population normalised daily prescriptions <40 mg day-1 1000 inh-1 and <80 mg day-1 1000 inh-1 for fluconazole and ketoconazole respectively). This was expected due to both prescription and over-the-counter usage, and both oral and topical applications. Pesticide AF, prothioconazole had PNDIs <40,000 mg day-1 1000 inh -1, which gave intake: 0.43, 0.26, 0.07 mg kg-1 in City A, B, and C, likely due to accounting for external/non-human sources. This is higher than the acceptable daily intake (ADI) of 0.01 mg kg-1bw day-1, which warrants further study. Intake per kg of body weight estimated using tebuconazole was 0.86, 1.39, 0.12, 0.13, and 2.7 mg kg-1 in City A-E respectively and is likely due to external/non-human sources. Intake calculated using its metabolite was 0.02 and 0.01 mg kg-1 in City B and C respectively, which aligned with ADI (0.03 mg kg-1bw day-1). The environmental risk assessment of AFs indicated low/medium risk from fluconazole, prochloraz, and tebuconazole, medium risk from epoxiconazole, prothioconazole's metabolite, and tebuconazole, and high risk for prothioconazole in river water. High risk was estimated from fluconazole, epoxiconazole, prothioconazole and its metabolite, tebuconazole, ketoconazole in wastewater samples, which is important during raw sewage discharge events via sewer overflows.

Direct injection liquid chromatography-tandem mass spectrometry as a sensitive and high-throughput method for the quantitative surveillance of antimicrobials in wastewater

Environmental antimicrobial pollution and antimicrobial resistance pose a threat to environmental and human health. Wastewater analysis has been identified as a promising tool for antimicrobial monitoring and the back-estimation of antimicrobial consumption, but current pretreatment methods are tedious and complicated, limiting their scope for high-throughput analysis. A sensitive direct injection method for the quantification of 109 antimicrobials and their metabolites in wastewater samples was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method was validated for both wastewater influent and effluent in terms of specificity, calibration range, matrix effect, filtration loss, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ). Most analytes achieved calibration of R2 > 0.99, and the calibration range was from 0.0002 to 150 μg L-1. Recoveries ranged consistently between ~50 % and ~100 % and losses were attributed to sample filtration. Method LOQs were determined as low as 0.0003 μg L-1, and acceptable accuracy (75 %-125 %) and precision (within 25 %) were achieved for >90 % of the analytes. The method was subsequently further assessed using wastewater of raw influent and treated effluent collected from 6 Australian wastewater treatment plants in 2021. In total, 37 analytes were detected in influent and 22 in effluent. Most of them could be quantified at concentrations ranging from 0.0053 to 160 μg L-1, with benzalkonium chloride-C12, amoxicilloic acid, and cephalexin detected at the highest concentrations. The current study provides a straightforward analytical method for antimicrobial monitoring in wastewater with a fast and simple pretreatment procedure.

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. β-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.

Antimicrobials and antimicrobial resistance genes in a one-year city metabolism longitudinal study using wastewater-based epidemiology

This longitudinal study tests correlations between antimicrobial agents (AA) and corresponding antimicrobial resistance genes (ARGs) generated by a community of >100 k people inhabiting one city (Bath) over a 13 month randomised monitoring programme of community wastewater. Several AAs experienced seasonal fluctuations, such as the macrolides erythromycin and clarithromycin that were found in higher loads in winter, whilst other AA levels, including sulfamethoxazole and sulfapyridine, stayed consistent over the study period. Interestingly, and as opposed to AAs, ARGs prevalence was found to be less variable, which indicates that fluctuations in AA usage might either not directly affect ARG levels or this process spans beyond the 13-month monitoring period. However, it is important to note that weekly positive correlations between individual associated AAs and ARGs were observed where seasonal variability in AA use was reported: ermB and macrolides CLR-clarithromycin and dmCLR-N-desmethyl clarithromycin, aSPY- N-acetyl sulfapyridine and sul1, and OFX-ofloxacin and qnrS. Furthermore, ARG loads normalised to 16S rRNA (gene load per microorganism) were positively correlated to the ARG loads normalised to the human population (gene load per capita), which indicates that the abundance of microorganisms is proportional to the size of human population and that the community size, and not AA levels, is a major driver of ARG levels in wastewater. Comparison of hospital and community wastewater showed higher number of AAs and their metabolites, their frequency of occurrence and concentrations in hospital wastewater. Examples include: LZD-linezolid (used only in severe bacterial infections) and AMX-amoxicillin (widely used, also in community but with very low wastewater stability) that were found only in hospital wastewater. CIP-ciprofloxacin, SMX-sulfamethoxazole, TMP-trimethoprim, MTZ-metronidazole and macrolides were found at much higher concentrations in hospital wastewater while TET-tetracycline and OTC-oxytetracycline, as well as antiretrovirals, had an opposite trend. In contrast, comparable concentrations of resistant genes were observed in both community and hospital wastewater. This supports the hypothesis that AMR levels are more of an endemic nature, developing over time in individual communities. Both hospital and community wastewater had AAs that exceeded PNEC values (e.g. CLR-clarithromycin, CIP-ciprofloxacin). In general, though, hospital effluents had a greater number of quantifiable AAs exceeding PNECs (e.g. SMX-sulfamethoxazole, ERY-erythromycin, TMP-trimethoprim). Hospitals are therefore an important consideration in AMR surveillance as could be high risk areas for AMR.

Community infectious disease treatment with antimicrobial agents - A longitudinal one year study of antimicrobials in two cities via wastewater-based epidemiology

Antimicrobial resistance (AMR) is one of the most significant global health threats. Inappropriate and over-usage of antimicrobial agents (AAs) is a major driver for AMR. Wastewater-based epidemiology (WBE) is a promising tool for monitoring AA usage in communities which is, for the first time, explored in this large scale, longitudinal study. Two contrasting urban catchment areas have been investigated: one city and one small town in the Southwest of the UK over a 13-month period in 2018-2019. Per capita daily intake of 17 AAs and metabolites has been estimated and obtained estimates were triangulated with catchment specific AA prescription data to understand AA usage patterns (both seasons driven prescription and AA prescription compliance). Results have demonstrated positive correlations for all quantifiable parent AAs and metabolites in wastewater, and spatial variability in AA usage was observed even in neighbouring urban areas. WBE and catchment specific prescription data showed similar seasonal trends but with low correlation in intake. The reasons might be variable prescribing patterns, prescription/intake outside the studied catchment, and/or lack of patient compliance. WBE proved useful in differentiating between consumption vs topical usage and/or direct disposal of unused AA. WBE is considered superior to prescription data as it provides information on AAs prescribed outside of the monitoring catchment, e.g. HIV antivirals and TB drugs. However, data triangulation, of both prescription data and wastewater data, provides the most comprehensive approach to understanding AA usage in communities.

Efficient Validation Strategies in Environmental Analytical Chemistry: A Focus on Organic Micropollutants in Water Samples

This article critically reviews analytical method validation and quality control applied to the environmental chemistry field. The review focuses on the determination of organic micropollutants (OMPs), specifically emerging contaminants and pesticides, in the aquatic environment. The analytical technique considered is (gas and liquid) chromatography coupled to mass spectrometry (MS), including high-resolution MS for wide-scope screening purposes. An analysis of current research practices outlined in the literature has been performed, and key issues and analytical challenges are identified and critically discussed. It is worth emphasizing the lack of specific guidelines applied to environmental analytical chemistry and the minimal regulation of OMPs in waters, which greatly affect method development and performance, requirements for method validation, and the subsequent application to samples. Finally, a proposal is made for method validation and data reporting, which can be understood as starting points for further discussion with specialists in environmental analytical chemistry.

Quantifying community-wide antibiotic usage via urban water fingerprinting: Focus on contrasting resource settings in South Africa

There has been a significant increase in antimicrobial agents (AAs) usage, globally - however the relative consumption is unevenly distributed between nations. Inappropriate use of antibiotics can harbour inherent antimicrobial resistance (AMR); therefore, it is important to understand and monitor community-wide prescribing and consumption behaviours throughout different communities around the world. Wastewater-Based Epidemiology (WBE) is a novel tool enabling low cost and large scale studies focussed on AA usage patterns. The back-calculation of community antimicrobial intake was performed from quantities measured in municipal wastewater and informal settlement discharge in the city of Stellenbosch, utilising WBE. Seventeen antimicrobials, and their human metabolites, were evaluated, in concordance with prescription records corresponding to the catchment region. The proportional excretion, biological/chemical stability, and method recovery of each analyte were all crucial factors in the efficacy of the calculation. Mass per day measurements were normalised to the catchment area via population estimates. Municipal wastewater treatment plant population estimates were used to normalise the wastewater samples and prescription data (mg/day/1000 inhabitants). Population estimates for the informal settlements were less accurate due to a lack of reliable sources that were relevant to the sampling time period. Both mass loads and normalised loads suggested higher than average usage throughout the settlements, relative to municipal wastewater. This was seen most prominently in emtricitabine and lamivudine; but also, sulfamethoxazole, trimethoprim, sulfadiazine, clindamycin, ciprofloxacin, ofloxacin, and doxycycline. Urban water fingerprinting (UWF) data triangulation with prescription datasets showed good correlations for several antimicrobial agents (AAs) (e.g., clindamycin, clarithromycin, ofloxacin, and doxycycline). It also revealed discrepancies in usage for some compounds (e.g., tetracycline and sulfapyridine). This might be linked with a lack of pharma compliance in prescription datasets; erroneous association of prescription boundaries with the sewerage catchment; and/or uncertainties within the sewerage catchment (e.g., population estimations). The UWF tool provided a comprehensive overview of multiclass AAs usage, both prescription and over-the counter. For example, tetracycline was not reported in available prescription statistics, but was detected at an average of 18.4 mg/day/1000inh; and no antiviral prescriptions were obtained, but emtricitabine and lamivudine were quantified at 2415.4 and 144.4 mg/day/1000inh, respectively. A lack of clarity regarding prescriptions and a lack of inclusion of several critical (often over-the-counter) medications in public health databases makes WBE a useful and comprehensive epidemiology tool for tracking pharma usage within a catchment.

Wastewater-based epidemiology for comprehensive community health diagnostics in a national surveillance study: Mining biochemical markers in wastewater

This manuscript showcases results from a large scale and comprehensive wastewater-based epidemiology (WBE) study focussed on multi-biomarker suite analysis of both chemical and biological determinants in 10 cities and towns across England equating to a population of ∼7 million people. Multi-biomarker suite analysis, describing city metabolism, can provide a holistic understanding to encompass all of human, and human-derived, activities of a city in a single model: from lifestyle choices (e.g. caffeine intake, nicotine) through to health status (e.g. prevalence of pathogenic organisms, usage of pharmaceuticals as proxy for non-communicable disease, NCD, conditions or infectious disease status), and exposure to harmful chemicals due to environmental and industrial sources (e.g. pesticide intake via contaminated food and industrial exposure). Population normalised daily loads (PNDLs) of many chemical markers were found, to a large extent, driven by the size of population contributing to wastewater (especially NCDs). However, there are several exceptions providing insights into chemical intake that can inform either disease status in various communities or unintentional exposure to hazardous chemicals: e.g. very high PNDLs of ibuprofen in Hull resulting from its direct disposal (confirmed by ibuprofen/2-hydroxyibuprofen ratios) and bisphenol A (BPA) in Hull, Lancaster and Portsmouth likely related to industrial discharge. An importance for tracking endogenous health markers such as 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA, an oxidative stress marker) as a generic marker of health status in communities was observed due to increased levels of HNE-MA seen at Barnoldswick wastewater treatment plant that coincided with higher-than-average paracetamol usage and SARS-CoV-2 prevalence in this community. PNDLs of virus markers were found to be highly variable. Being very prevalent in communities nationwide during sampling, SARS-CoV-2 presence in wastewater was to a large extent community driven. The same applies to the fecal marker virus, crAssphage, which is very prevalent in urban communities. In contrast, norovirus and enterovirus showed much higher variability in prevalence across all sites investigated, with clear cases of localized outbreaks in some cities while maintaining low prevalence in other locations. In conclusion, this study clearly demonstrates the potential for WBE to provide an integrated assessment of community health which can help target and validate policy interventions aimed at improving public health and wellbeing.

In-situ multi-mode extraction (iMME) sampler for a wide-scope analysis of chemical and biological targets in water in urbanized and remote (off-the-grid) locations

Chemical pollution (including chemicals of emerging concern - CECs) continues to gain increasing attention as a global threat to human health and the environment, with numerous reports on the adverse and sometimes devastating effects upon ecosystems the presence of these chemicals can have. Whilst many studies have investigated presence of CECs in aquatic environments, these studies have been often focused on higher income countries, leaving significant knowledge gaps for many low-middle income countries. This study proposes a new integrated powerless, in-situ multi-mode extraction (iMME) sampler for the analysis of chemicals (105 CECs) and biological (5 genes) markers in water in contrasting settings: an urbanized Avon River in the UK and remote Olifants River in Kruger National Park in South Africa. The overarching goal was to develop a sampling device that maintains integrity of a diverse range of analytes via analyte immobilization using polymeric and glass fibre materials, without access to power supply or cold chain (continuous chilled storage) for sample transportation. Chemical analysis was achieved using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Several mobile CECs showed low stability in river water, at room temperature and typical 24 h sampling/transport time. It is therefore recommended that, in the absence of cooling, environmental water samples are spiked with internal standards on site, immediately after collection and analyte immobilization option is considered, in order to allow fully quantitative analysis. iMME has proven effective in immobilization, concentration and increased stability of CECs at room temperature (and at least 7 days storage) allowing for sample collection at remote locations. The results from the River Avon and Olifants River sampling indicate that the pristine environment of Olifants catchment is largely unaffected by CECs common in the urbanized River Avon in the UK with a few exceptions: lifestyle chemicals (e.g., caffeine, nicotine and their metabolites), paracetamol and UV filters due to tourism and carbamazepine due to its persistent nature. iMME equipped with an additional gene extraction capability provides an exciting new opportunity of comprehensive biochemical profiling of aqueous samples with one powerless in-situ device. Further work is required to provide full integration of the device and comprehensive assessment of performance in both chemical and biological targets.

Application of wastewater-based epidemiology for estimating population-wide human exposure to phthalate esters, bisphenols, and terephthalic acid

Phthalates, bisphenols (BPs), and terephthalic acid (TPA) are widely used plasticizers and monomers in plastic manufacturing. Most of them are known to have an adverse effect on the human body, functioning as endocrine disruptors and suspected carcinogens. Access to near real-time data on population exposure to plasticizers is essential for identifying vulnerable communities and better protecting and managing public health locally. The objective of the present study was to evaluate population-level exposure to phthalates, BPs, and TPA by measuring urinary metabolites in community wastewater. Composited community wastewater (24-h samples) from five sewer sub-catchments of a southwestern city within the United States were analyzed for urinary biomarkers of phthalates, BPs, and TPA using solid-phase extraction-liquid chromatography-tandem mass spectrometry in conjunction with the isotope dilution method for absolute quantification. Ten of 16 analytes were detected at least once in community wastewater above the method detection limit (MDL), with MDLs ranging from 37 to 203 ng/L. The population normalized mass load of TPA was the highest, followed by the human metabolite of di-(2-ethylhexyl) phthalate (DEHP). Bisphenol S and monoethyl phthalate were detected with the highest frequency. Study findings suggest that analyzing municipal wastewater for chemical indicators of human exposure to plastic constituents is feasible, practicable, and informative, as long as appropriate steps are taken to determine, quantify and account for background levels of plastic analytes in the laboratory environment.

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 β-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.

Quantifying community-wide antimicrobials usage via wastewater-based epidemiology

Increasing usage of antimicrobials is a significant contributor to the emergence and dissemination of antimicrobial resistance. Wastewater-based epidemiology is a useful tool for evaluating public health, via the monitoring of chemical and biological markers in wastewater influent, such as antibiotics. Sixteen antimicrobials and their metabolites were studied: sulfonamides, trimethoprim, metronidazole, quinolones, nitrofurantoin, cyclines, and antiretrovirals. Correction factors (CFs) for human drug excretion, for various drug forms, were determined via a systematic literature review of pharmacokinetic research. Analyte stability was examined over a 24 h study. The estimation of community-wide drug intake was evaluated using the corresponding catchment prescription data. Overall, antimicrobials excreted in an unchanged form were often observed to over-estimate daily intake. This could be attributed to biotransformation, e.g., via glucuronide cleavage, or direct disposal of unused drugs. Acetyl-sulfonamides, trimethoprim, hydroxy-metronidazole, clarithromycin, ciprofloxacin, ofloxacin, tetracycline, and oxytetracycline generally performed well in the estimation of drug intake, relative to prescription records. The low prevalence of quinolone and trimethoprim metabolites, and the low stability of nitrofurantoin, limited the ability to evaluate these metabolites and their respective CFs.

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.

Spatiotemporal urban water profiling for the assessment of environmental and public exposure to antimicrobials (antibiotics, antifungals, and antivirals) in the Eerste River Catchment, South Africa

Antimicrobial agent (AA) usage, excretion, and persistence are all important factors in association with the occurrence and dissemination of antimicrobial resistance. Urban water profiling was utilised in the Eerste River catchment (South Africa) to establish AA usage in a region where comprehensive prescription records were not readily available and where portions of the community did not have sufficient access to sanitation. This technique enabled the environmental exposure to be quantified throughout the catchment area and the identification of contamination hotspots. Monitoring occurred over a 11-month period. 812 samples were processed using UPLC-MS/MS for the quantitation of 56 antimicrobials and 26 of their metabolites. Spatiotemporal trends were established, with consideration to community behaviour, seasonal changes, and physiochemical properties of the analytes. The Eerste River samples collected upstream from the town of Stellenbosch had the lowest AA loads (<4 g/day), unafflicted by industrial presence and with only small impact from farming activities. This was followed by sites downstream from a wastewater treatment plant (serving 178 K people). The measurement of low AA loads (influent: 500-800 g/day and effluent 50-100 g/day), indicates a high efficiency of wastewater treatment, allowing for an effective reduction of AA and a lower environmental burden. This is compared to river sites that receive untreated waste from communities in informal settlements (6-12 K people) that are not connected to the sewer infrastructure (with AA levels accounting for 100-600 g/day). Temporal trends exhibited reduced daily loads during the summer to early autumn (Nov-May). This is likely due to seasonal patterns in community health and/or notable changes in rainfall and temperatures at the sampling locations throughout the year. However, weather patterns are also important to consider - particularly for the river sites. South Africa has notable rainfall and temperature seasonality. Antiretrovirals (ARV), emtricitabine and lamivudine, were the most prevalent drugs throughout the monitoring campaign, followed by tuberculosis drugs and sulfonamides. ARVs were, however, effectively reduced via wastewater treatment processes (>97%). This was also the case for beta-lactams, nitrofurantoin, and trimethoprim. The treatment efficacy for other drugs was more variable, that did not appear to have temporal significance.