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Klebsiellaspecies, includingKlebsiella pneumoniae, Klebsiella aerogenes, andKlebsiella quasipneumoniae, are opportunistic pathogens that are known to cause infections in humans. HypervirulentKlebsiella pneumoniae(hvKP) is a subgroup ofK. pneumoniaethat has gained attention due to its global dissemination and its ability to cause invasive infections in community settings amongst immunocompetent individuals as well as its increasing levels of antibiotic resistance. Our study reports the first complete genotypic analysis including mobile genetic elements (MGEs) ofKlebsiellaisolates from the International Space Station (ISS). The genomes ofK. pneumoniae, K. aerogenes, andK. quasipneumoniaeprovided valuable insights into their antimicrobial resistance, virulence, thermotolerance, disinfectant resistance, and MGEs. All isolates belonged to emerging lineages with pathogenic potential, withK. quasipneumoniaeST138 presenting spatial and temporal persistence aboard the ISS, possibly due to its genotypic profile encoding for numerous resistance genes to disinfectants and heavy metals. We also report on the isolation of a yersiniabactin encodingK. pneumoniae, belonging to the emerging high-risk ST101 clone, aboard the ISS. Potential dissemination of hvKp strains on ISS could pose a putative risk to the immunocompromised crew. The presence of MGEs containing virulent loci could facilitate horizontal gene transfer to other benign microorganisms on the ISS, potentially increasing their virulence. In addition, genetic divergence from their respective lineages for someKlebsiellagenomes was predicted and hypothesized to be due to the unique spaceflight environmental pressures. These findings highlight the importance of monitoring problematic microbial communities in space to understand their surviving abilities and potential impact on human health.ImportanceThe International Space Station (ISS) is a unique hermetically sealed environment that poses environmental pressures not encountered on Earth, including microgravity and radiation While the adaptability of bacteria during spaceflight is not fully understood, recent research has suggested that it may be species and even clone specific. Given the spaceflight-induced suppression of the human immune system, it is essential to understand the genomics of potential human pathogens in spaceflight. Such understanding could provide valuable insights into species and lineages of medical astromicrobiological importance. Here, we used hybrid assembly approaches and comparative genomics to provide the first comprehensive genomic characterisation of 10Klebsiellaisolates retrieved from the ISS. Our findings revealed thatK. quasipneumoniaeST138 exhibits spatial and temporal persistence aboard the ISS, with evidence of genomic divergence from the ST138 lineage on Earth. Additionally, we characterized plasmids fromKlebsiellaspecies of ISS origin, which encoded disinfectant and thermoresistance genes suggesting that these might aid adaptability. Furthermore, we identified an MGE containing a hypervirulence-associated locus belonging to aKlebsiella pneumoniaeisolate of the “high risk” ST101 clone. Our work provides valuable insights into the adaptability and persistence ofKlebsiellaspecies during spaceflight, highlighting the importance of understanding the behaviour of potential pathogenic bacteria in space.

The second and third decades of the twenty-first century are marked by a flourishing of space technology which may soon realise human aspirations of a permanent multiplanetary presence. The prevention, control and management of infection with microbial pathogens is likely to play a key role in how successful human space aspirations will become. This review considers the emerging field of medical astro-microbiology. It examines the current evidence regarding the risk of infection during spaceflight via host susceptibility, alterations to the host’s microbiome as well as exposure to other crew members and spacecraft’s microbiomes. It also considers the relevance of the hygiene hypothesis in this regard. It then reviews the current evidence related to infection risk associated with microbial adaptability in spaceflight conditions. There is a particular focus on the International Space Station (ISS), as one of the only two crewed objects in low Earth orbit. It discusses the effects of spaceflight related stressors on viruses and the infection risks associated with latent viral reactivation and increased viral shedding during spaceflight. It then examines the effects of the same stressors on bacteria, particularly in relation to changes in virulence and drug resistance. It also considers our current understanding of fungal adaptability in spaceflight. The global public health and environmental risks associated with a possible re-introduction to Earth of invasive species are also briefly discussed. Finally, this review examines the largely unknown microbiology and infection implications of celestial body habitation with an emphasis placed on Mars. Overall, this review summarises much of our current understanding of medical astro-microbiology and identifies significant knowledge gaps. Graphical Abstract

The emergence and dissemination of mobile colistin resistance (mcr) genes across the globe poses a significant threat to public health, as colistin remains one of the last line treatment options for multi-drug resistant infections. Environmental samples (157 water and 157 wastewater) were collected in Ireland between 2018 and 2020. Samples collected were assessed for the presence of antimicrobial resistant bacteria using Brilliance ESBL, Brilliance CRE, mSuperCARBA and McConkey agar containing a ciprofloxacin disc. All water and integrated constructed wetland influent and effluent samples were filtered and enriched in buffered peptone water prior to culture, while wastewater samples were cultured directly. Isolates collected were identified via MALDI-TOF, were tested for susceptibility to 16 antimicrobials, including colistin, and subsequently underwent whole genome sequencing. Overall, eightmcrpositive Enterobacterales (onemcr-8 and sevenmcr-9) were recovered from six samples (freshwater (n=2), healthcare facility wastewater (n=2), wastewater treatment plant influent (n=1) and integrated constructed wetland influent (piggery farm waste) (n=1)). While themcr-8 positiveK. pneumoniaedisplayed resistance to colistin, all sevenmcr-9 harbouring Enterobacterales remained susceptible. All isolates demonstrated multi-drug resistance and through whole genome sequencing analysis, were found to harbour a wide variety of antimicrobial resistance genes i.e., 30 ± 4.1 (10-61), including the carbapenemases,blaOXA-48(n=2) andblaNDM-1(n=1), which were harboured by three of the isolates. Themcrgenes were located on IncHI2, IncFIIK and IncI1-like plasmids. The findings of this study highlight potential sources and reservoirs ofmcrgenes in the environment and illustrate the need for further research to gain a better understanding of the role the environment plays in the persistence and dissemination of antimicrobial resistance.

Over recent years, Ireland has reported the highest crude incidence rates of Shiga toxin-producing Escherichia coli (STEC) enteritis in Europe. Unregulated private groundwater sources have emerged as an important potential transmission route for STEC, with up to 750,000 Irish residents reliant on these sources for domestic waters. This study aimed to investigate the prevalence and serogroup profile of STEC contamination from domestic private wells in western Ireland. Fifty-two groundwater sources were analysed during two sampling campaigns in the autumn (September/October) of 2019 (n = 21) and 2021 (n = 31). Untreated groundwater samples (30 L) were collected and analysed using the "CapE" (capture, amplify, extract) method. Extracted DNA was tested using multiplex real-time PCR for Shiga toxin stx1 and/or stx2 and eae genes. STEC positive DNA samples were tested for clinically relevant serogroups by real-time PCR. Data relating to 27 potential groundwater contamination risk factors were geospatially linked to each well and assessed for association with E. coli, stx1 and/or stx2 and eae presence/absence. Overall, 20/52 wells (38.4 %) were positive for E. coli (median concentration 8.5 MPN/100 mL as assessed by Colilert-18 method). Stx1 and/or stx2 was detected in 10/52 (19.2 %) wells overall and 8/20 E. coli positive wells, equating to a STEC to "generic" E. coli detection ratio of 40 %. Six of these wells (30 %) were also positive for eae. One or more serogroup-specific gene targets were identified in all but one stx1 and/or stx2 positive sample, with O145 (n = 6), O157 (n = 5) and O103 (n = 4) most prevalent. STEC presence was significantly associated with decreasing well depth (U = -2.243; p = 0.024) and increasing 30-day mean antecedent rainfall (U = 2.126; p = 0.034). Serogroup O104 was associated with increased sheep density (U = 2.089; p = 0.044) and detection of stx1 and/or stx2 + eae with increased septic tank density (U = 2.246 p = 0.023). Findings indicate high detection rates of clinically relevant STEC in E. coli contaminated groundwater sources in Ireland.

Antimicrobial resistance is a major concern for human and animal health, projected to deteriorate with time and given current trends of antimicrobial usage. Antimicrobial use, particularly in healthcare and agriculture, can result in the release of antimicrobials into surface waters, promoting the development of antibiotic resistance in the environment, and potentially leading to human health risks. This study reviews relevant literature, and investigates current European and Irish antimicrobial usage trends in humans and animals, as well as potential pathways that antibiotics can take into surface waters following use. Reported levels in the aquatic environment are summarized, with particular focus on Ireland. There are relatively few studies examining Irish water bodies or sewage effluent for antibiotic residues, however, five antibiotics, namely azithromycin, ciprofloxacin, clarithromycin, metronidazole, and trimethoprim, have been measured in Irish waters, in concentrations predicted to select for resistance. Numerous isolates of multi-drug resistant bacteria have also been found in water bodies throughout Ireland and Europe. The value of risk assessment methodologies in understanding risks posed by antibiotic residues is reviewed including the advantages and disadvantages of specific approaches. Hazard quotient and bespoke Monte Carlo approaches are predominant risk assessment tools used to examine antimicrobial release and their complex pathways. This study highlights the need for monitoring of antimicrobial releases and the potential for resistance development, persistence and transmission while highlighting the role of risk assessment methodologies in assessing potential human and environmental health impacts.

OHEJP Project: HME-AMR Literature review on the impact of heavy metals as a selective pressure for the dissemination of AMR in the primary food production environment.

Klebsiella pneumoniae species complex (KpSC) is a leading cause of multidrug-resistant human infections. To better understand the potential contribution of food as a vehicle of KpSC, we conducted a multicentric study to define an optimal culture method for its recovery from food matrices, and to characterize food isolates phenotypically and genotypically. Chicken meat (n=160) and salad (n=145) samples were collected in five European countries and screened for KpSC presence using culture-based and ZKIR qPCR methods. Enrichment using buffered peptone water followed by streaking on Simmons citrate agar with inositol (44°C/48h) was defined as the most suitable selective culture method for KpSC recovery. High prevalence of KpSC was found in chicken meat (60% and 52% by ZKIR qPCR and culture approach, respectively) and salad (30% and 21%, respectively) samples. Genomic analyses revealed high genetic diversity with the dominance of phylogroups Kp1 (91%) and Kp3 (6%). 82% of isolates presented a natural antimicrobial susceptibility phenotype and genotype, with only four CTX-M-15-producing isolates detected. Notably, identical genotypes were found across samples: same food type and same country (15 cases); different food types and same country (1); same food type and two countries (1), suggesting high rates of transmission of KpSC within the food sector. Our study provides a novel isolation strategy for KpSC from food matrices and reinforces the view of food as a potential source of KpSC colonization in humans.ImportanceBacteria of the Klebsiella pneumoniae species complex (KpSC) are ubiquitous and K. pneumoniae (Kp) is a leading cause of antibiotic-resistant infections in humans and animals. Despite the urgent public health threat represented by Kp, there is a lack of knowledge on the contribution of food sources to colonization and subsequent infection in humans. This is partly due to the absence of standardized methods for characterizing KpSC presence in food matrices. Our multicentric study provides and implements a novel isolation strategy for KpSC from food matrices and shows that KpSC members are highly prevalent in salads and chicken meat, reinforcing the view of food as a potential source of KpSC colonization in humans. Despite the large genetic diversity and the low-levels of resistance detected, the occurrence of identical genotypes across samples suggests high rates of transmission of KpSC within the food sector, which need to be further explored to define possible control strategies.

WorldCOM 12M progress report

This study investigated the ability of Integrated Constructed Wetlands (ICWs) to remove critically important antimicrobial resistant organisms (AROs) from farm wastewater. Influent samples from the untreated farm waste and effluent samples taken at the end of the ICW system were collected monthly from four ICWs, serving four different farm types (suckler, dairy, dairy & poultry and pig). Using selective media to screen for the presence of carbapenemase resistant organisms, plasmid mediated and AmpC β-Lactamase producing organisms (ESBL/pAmpC) and fluoroquinolone resistant organisms, a total of 82 AROs were obtained with the majority being E. coli (n = 79). Statistically significant were the differences on the number of AROs isolated from influent (higher) compared to effluent, as well as a seasonal effect, with less AROs recovered during winter in comparison to other seasons (P < 0.05). On the other hand, there was no significant differences in the recovery of AROs on different farms. The majority of isolates from each of the farms (99%) were multi drug resistant, with 65% resistant to seven or more antimicrobials. A high incidence of tetracycline, trimethoprim/sulfamethoxazole, and ampicillin resistance was common to the isolates from all four farms but there were differences in ESBL levels with 63% of the isolates recovered from Farm 4 (piggery) being ESBLs compared to 18%, 36% and 4.5% recovered from Farms 1 (suckler), 2 (dairy) and 3 (dairy & poultry), respectively. No carbapenemase producing organisms were isolated. Our results showed that ICWs are effective in removing critically important AROs from farm wastewater on all four farm types.

The natural environment represents a complex reservoir of antibiotic-resistant bacteria as a consequence of different wastewater discharges including anthropogenic and agricultural. Therefore, the aim of this study was to examine sewage and waters across Ireland for the presence of antibiotic-resistant Enterobacterales. Samples were collected from the West, East and South of Ireland. Two periods of sampling took place between July 2019 and November 2020, during which 118 water (30 L) and 36 sewage samples (200 mL) were collected. Waters were filtered using the CapE method, followed by enrichment and culturing. Sewage samples were directly cultured on selective agars. Isolates were identified by MALDI-TOF and antibiotic susceptibility testing was performed in accordance with EUCAST criteria. Selected isolates were examined for blaCTX-M, blaVIM, blaIMP, blaOXA-48, blaNDM, and blaKPC by real time PCR and whole genome sequencing (n = 146). A total of 419 Enterobacterales (348 water, 71 sewage) were isolated from all samples. Hospital sewage isolates displayed the highest percentage resistance to many beta-lactam and aminoglycoside antibiotics. Extended-spectrum beta-lactamase-producers were identified in 78% of water and 50% of sewage samples. One or more carbapenemase-producing Enterobacterales were identified at 23 individual sampling sites (18 water, 5 sewage). This included the detection of blaOXA-48 (n = 18), blaNDM (n = 14), blaKPC (n = 4) and blaOXA-484 (n = 1). All NDM-producing isolates harbored the ble-MBL bleomycin resistance gene. Commonly detected sequence types included Klebsiella ST323, ST17, and ST405 as well as E. coli ST131, ST38 and ST10. Core genome MLST comparisons detected identical E. coli isolates from wastewater treatment plant (WWTP) influent and nursing home sewage, and the surrounding waters. Similarly, one Klebsiella pneumoniae isolated from WWTP influent and the surrounding estuarine water were identical. These results highlight the need for regular monitoring of the aquatic environment for the presence of antibiotic-resistant organisms to adequately inform public health policies. This project is jointly funded by the Environmental Protection Agency, under the EPA Research Programme 2014–2020, and the Health Service Executive (2017-HW-LS-1). The EPA Research Programme is a Government of Ireland initiative funded by the Department of Communications, Climate Action and Environment. It is administered by the Environmental Protection Agency, which has the statutory function of co-ordinating and promoting environmental research. A portion of this work was also financially supported by the MedVetKlebs project, a component of the European Joint Programme One Health EJP, which has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 773830. peer-reviewed

Antibiotic use in the healthcare and agriculture sectors has resulted in levels being found in environmental compartments including surface waters. This can create a selective pressure toward antibiotic resistance development, representing a potential risk to human health. Examining the Irish scenario, this screening paper develops a novel risk ranking model to comparatively assess, on a national scale, the predicted amount of antibiotics entering water bodies as a result of their use in healthcare and agricultural sectors, and the subsequent risk of antibiotic resistance development. Probabilistic modelling approaches, based on data sourced from published literature on antibiotics, are used to account for inherent uncertainty and variability in the input factors; usage, metabolism, degradation and wastewater removal rates, estimating the mass of six antibiotic classes released daily from both sectors. These mass estimates are used to generate predicted concentrations and risk quotient values for each drug class, utilising estimated minimum inhibitory concentration values sourced from the literature. Modelled results predict higher risk quotient (RQ) values in the healthcare compared to agriculture sector, with macrolides and penicillins ranking highest in terms of RQ value. A lower RQ is also predicted from human-use tetracyclines, trimethoprim, and quinolones. Avenues for runoff reduction for each antibiotic class, in particular the higher-risk classes, in both usage sectors are discussed. For validation, predicted levels are compared to observed levels of antibiotic residues in Ireland. Key knowledge gaps to assist prediction and modelling of antibiotic pollution in future studies are also discussed. This research paper establishes a protocol and model structure, applicable to other regions, to compare the contributions of healthcare and agriculture to antibiotic pollution, and identifies highest-ranked antibiotic classes in terms of potential resistance development for prioritisation in the Irish situation.

Silver nanoparticles (AgNPs), due to their antibacterial activity, have been incorporated into numerous consumer products. Their environmental impact however, is currently unclear. Uncertainties surround the concentration, fate, and effects of AgNPs in aquatic environments. This study examined the suitability of activated charcoal as a capture material for AgNPs from water. Samples of 100 ppb AgNPs were initially generated and exposed to activated charcoal for 24 h to examine the ability of charcoal to capture AgNPs. The decrease in Ag concentration was measured using ICP-MS. Following initial investigations, the surface area of the charcoal was increased firstly with a pestle and mortar and secondly by milling the charcoal using a ball mill. The increased surface area of the milled charcoal increased the capture of the AgNPs from 11.9% to 63.6% for the 100 ppb samples. Further investigations were carried out examining the effect on the capture of AgNP concentration (with concentration ranging from 10 to 100 ppb), particle coating and the effect of exposure time to the activated charcoal. The capture of AgNP increased with decreasing concentration. A hydrochloric acid (HCl) leaching procedure was also developed which successfully removed the captured silver allowing the fraction captured by the charcoal to be quantified with an average of 94.8% recovery. The results show that milled activated charcoal, can successfully capture AgNPs from water samples, and that therefore, activated charcoal may prove to be a cost effective material for the remediation of waters impacted by AgNP or other nano-wastes.

Globally, water-based bathing pastimes are important for both mental and physical health. However, exposure to waterborne organisms could present a substantial public health issue. Bathing waters are shown to contribute to the transmission of illness and disease and represent a reservoir and pathway for the dissemination of antimicrobial resistant (AMR) organisms. Current bathing water quality regulations focus on enumeration of faecal indicator organisms and are not designed for detection of specific waterborne organisms of public health concern (WOPHC), such as antimicrobial resistant (AMR)/pathogenic bacteria, or viruses. This investigation presents the first scoping review of the occurrence of waterborne organisms of public health concern (WOPHC) in identified natural bathing waters across the European Union (EU), which aimed to critically evaluate the potential risk of human exposure and to assess the appropriateness of the current EU bathing water regulations for the protection of public health. Accordingly, this review sought to identify and synthesise all literature pertaining to a selection of bacterial (Campylobacter spp., Escherichia coli, Salmonella spp., Shigella spp., Vibrio spp., Pseudomonas spp., AMR bacteria), viral (Hepatitis spp., enteroviruses, rotavirus, adenovirus, norovirus), and protozoan (Giardia spp., and Cryptosporidium spp.) contaminants in EU bathing waters. Sixty investigations were identified as eligible for inclusion and data was extracted. Peer-reviewed investigations included were from 18 countries across the EU, totalling 87 investigations across a period of 35 years, with 30% published between 2011 and 2015. A variety of water bodies were identified, with 27 investigations exclusively assessing coastal waters. Waterborne organisms were classified into three categories; bacteria, viruses, and protozoa; amounting to 58%, 36% and 17% of the total investigations, respectively. The total number of samples across all investigations was 8,118, with detection of one or more organisms in 2,449 (30%) of these. Viruses were detected in 1281 (52%) of all samples where WOPHC were found, followed by bacteria (865(35%)) and protozoa (303(12%)). Where assessed (442 samples), AMR bacteria had a 47% detection rate, emphasising their widespread occurrence in bathing waters. Results of this scoping review highlight the potential public health risk of exposure to WOPHC in bathing waters that normally remain undetected within the current monitoring parameters.

Water bodies worldwide have proven to be vast reservoirs of clinically significant antibiotic resistant organisms. Contamination of waters by anthropogenic discharges is a significant contributor to the widespread dissemination of antibiotic resistance. The aim of this research was to investigate multiple different anthropogenic sources on a national scale for the role they play in the environmental propagation of antibiotic resistance. A total of 39 water and 25 sewage samples were collected across four local authority areas in the West, East and South of Ireland. In total, 211 Enterobacterales were isolated (139 water, 72 sewage) and characterised. A subset of isolates (n=60) were chosen for whole genome sequencing. Direct comparisons of the water versus sewage isolate collections revealed a higher percentage of sewage isolates displayed resistance to cefoxitin (46%) and ertapenem (32%), while a higher percentage of water isolates displayed resistance to tetracycline (55%) and ciprofloxacin (71%). Half of all isolates displayed extended spectrum beta-lactamase (ESBL) production phenotypically (n = 105/211; 50%), with blaCTX-M detected in 99/105 isolates by PCR. Carbapenemase genes were identified in 11 isolates (6 sewage, 5 water). The most common variant was blaOXA-48 (n=6), followed by blaNDM-5 (n=2) and blaKPC-2 (n=2). Whole genome sequencing analysis revealed numerous different sequence types in circulation in both waters and sewage including E. coli ST131 (n=15), ST38 (n=8), ST10 (n=4) along with Klebsiella ST405 (n=3) and ST11 (n=2). Core genome MLST (cgMLST) comparisons uncovered three highly similar Klebsiella isolates originating from hospital sewage and two nearby waters. The Klebsiella isolates from an estuary and seawater displayed 99.1% and 98.8% cgMLST identity to the hospital sewage isolate respectively. In addition, three pairs of E. coli isolates from different waters also revealed cgMLST similarities, indicating widespread dissemination and persistence of certain strains in the aquatic environment. These findings highlight the need for routine monitoring of water bodies used for recreational and drinking purposes for the presence of multi-drug resistant organisms. This project is jointly funded by the Environmental Protection agency, under the EPA Research Programme 2014-2020, and the Health Service Executive (2017-HW-LS-1). The EPA Research Programme is a Government of Ireland initiative funded by the Department of Communications, Climate Action and Environment. It is administered by the Environmental Protection Agency, which has the statutory function of co-ordinating and promoting environmental research. A portion of this work was also financially supported by the MedVetKlebs project, a component of the European Joint Programme One Health EJP, which has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 773830. peer-reviewed

Coronavirus disease 2019 (COVID-19), the respiratory illness caused by the novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has lead to high morbidity and mortality rates worldwide, has been causing major public health concerns since first detected in late 2019. Following identification of novel pathogens, questions in relation to dissemination of the pathogen and transmission routes begin to emerge. This rapidly spreading SARS-CoV-2 virus has been detected in both faecal and wastewater samples across the globe, highlighting the potential for faecal-oral transmission of the virus. As a result, concerns regarding the transmission of the virus in the environment and the risk associated with contracting the virus in recreational waters, particularly where inadequately treated wastewater is discharged, have been emerging in recent weeks. This paper highlights the need for further research to be carried out to investigate the presence, infectivity and viability of this newly identified SARS-CoV-2 virus in wastewater effluent and receiving recreational waters., Graphical abstract Unlabelled Image, Highlights • SARS-CoV-2 has been detected in faeces and wastewater in recent months. • Wastewater is a potential dissemination route for SARS-CoV-2 to recreational waters. • Limited data on the presence and viability of SARS-CoV-2 in water bodies exists. • The risk of SARS-CoV-2 exposure to recreational water users is believed to be low. • Further research investigating SARS-CoV-2 in recreational waters is required.

peer-reviewed Verocytotoxin-producing E. coli (VTEC) are important agents of diarrhoeal disease in humans globally. As a noted waterborne disease, emphasis has been given to the study VTEC in surface waters, readily susceptible to microbial contamination. Conversely, the status of VTEC in potable groundwater sources, generally regarded as a “safe” drinking-water supply remains largely understudied. As such, this investigation presents the first scoping review seeking to determine the global prevalence of VTEC in groundwater supply sources intended for human consumption. Twenty-three peer-reviewed studies were identified and included for data extraction. Groundwater sample and supply detection rates (estimated 0.6 and 1.3%, respectively) indicate VTEC is infrequently present in domestic groundwater sources. However, where generic (fecal indicator) E. coli are present, the VTEC to E. coli ratio was found to be 9.9%, representing a latent health concern for groundwater consumers. Geographically, extracted data indicates higher VTEC detection rates in urban (5.4%) and peri–urban (4.9%) environments than in rural areas (0.9%); however, this finding is confounded by the predominance of research studies in lower income regions. Climate trends indicate local environments classified as ‘temperate’ (14/554; 2.5%) and ‘cold’ (8/392; 2%) accounted for a majority of supply sources with VTEC present, with similar detection rates encountered among supplies sampled during periods typically characterized by ‘high’ precipitation (15/649; 2.3%). Proposed prevalence figures may find application in preventive risk-based catchment and groundwater quality management including development of Quantitative Microbial Risk Assessments (QMRA). Notwithstanding, to an extent, a large geographical disparity in available investigations, lack of standardized reporting, and bias in source selection, restrict the transferability of research findings. Overall, the mechanisms responsible for VTEC transport and ingress into groundwater supplies remain ambiguous, representing a critical knowledge gap, and denoting a distinctive lack of integration between hydrogeological and public health research. Key recommendations and guidelines are provided for prospective studies directed at increasingly integrative and multi-disciplinary research.

The natural aquatic environment is a significant contributor to the development and circulation of clinically significant antibiotic resistance genes (ARGs). The potential for the aquatic environment to act as a reservoir for ARG accumulation in areas receiving anthropogenic contamination has been thoroughly researched. However, the emergence of novel ARGs in the absence of external influences, as well as the capacity of environmental bacteria to disseminate ARGs via mobile genetic elements remain relatively unchallenged. In order to address these knowledge gaps, this scoping literature review was established focusing on the detection of two important and readily mobile ARGs, namely, extended spectrum beta-lactamase (ESBL) and carbapenemase genes. This review included 41 studies from 19 different countries. A range of different water bodies including rivers (n = 26), seawaters (n = 6) and lakes (n = 3), amongst others, were analysed in the included studies. ESBL genes were reported in 29/41 (70.7%) studies, while carbapenemase genes were reported in 13/41 (31.7%), including joint reporting in 9 studies. The occurrence of mobile genetic elements was evaluated, which included the detection of integrons (n = 22), plasmids (n = 18), insertion sequences (n = 4) and transposons (n = 3). The ability of environmental bacteria to successfully transfer resistance genes via conjugation was also examined in 11 of the included studies. The findings of this scoping review expose the presence of clinically significant ARGs in the natural aquatic environment and highlights the potential ability of environmental isolates to disseminate these genes among different bacterial species. As such, the results presented demonstrate how anthropogenic point discharges may not act as the sole contributor to the development and spread of clinically significant antibiotic resistances. A number of critical knowledge gaps in current research were also identified. Key highlights include the limited number of studies focusing on antibiotic resistance in uncontaminated aquatic environments as well as the lack of standardisation among methodologies of reviewed investigations. This review was carried out as part of the AREST (Antimicrobial Resistance and the Environment – Sources, persistence, transmission and risk management) project which is jointly funded by the Irish Environmental Protection Agency and the Health Service Executive (Grant number 2017-HW-LS-1). peer-reviewed

Escherichia colisequence type 131 (ST131) is a pandemic clone that is evolving rapidly with increasing levels of antimicrobial resistance. Here, we investigated an outbreak ofE. coliST131 producing extended spectrum β-lactamases (ESBLs) in a long-term care facility (LTCF) in Ireland by combining data from this LTCF (n=69) with other Irish (n=35) and global (n=690) ST131 genomes to reconstruct the evolutionary history and understand changes in population structure and genome architecture over time. This required a combination of short and long-read genome sequencing,de novoassembly, read mapping, ESBL gene screening, plasmid alignment and temporal phylogenetics. We found that clade C was the most prevalent (686 out of 794 isolates, 86%) of the three major ST131 clades circulating worldwide (A, B, C), and was associated with the presence of different ESBL alleles, diverse plasmids and transposable elements. Clade C was estimated to have emerged in ∼1985 and subsequently acquired different ESBL gene variants (blaCTX-M-14vsblaCTX-M-15). An ISEcp1-mediated transposition of theblaCTX-M-15gene further increased the diversity within Clade C. We discovered a local clonal expansion of a rare C2 lineage (C2_8) with a chromosomal insertion ofblaCTX-M-15at themppAgene. This was acquired from an IncFIA plasmid. The C2_8 lineage clonally expanded in the Irish LTCF from 2006, displacing the existing C1 strain (C1_10) and highlighting the potential for novel ESBL-producing ST131 with a distinct genetic profile to cause outbreaks strongly associated with specific healthcare environments.ImportanceExtraintestinal pathogenicE. coli(ExPEC) ST131 is adapting in the context of antibiotic exposure, resulting in a pandemic with distinct genetic subtypes. Here, we track the evolution of antibiotic-resistance gene variants originally discovered in an ExPEC ST131 outbreak that was identified in a LTCF in Ireland. Analysis of 794 global ST131 genomes show that subclade C1 was associated with the initial infection outbreak, but that a new lineage from subclade C2 successfully displaced C1. This genetically distinct C2 subclade with a chromosomal insertion of a key antibiotic-resistance gene had clonally expanded within the LTCF. We provide new insights into the timing of genetic events driving the diversification of C2 subclades to show that that outbreak C2 strain likely evolved elsewhere before spreading to the LTCF. This study highlights the scope of antibiotic-resistance gene rearrangement within ST131, reinforcing the need to integrate genomic, epidemiological and microbiological approaches to understand ST131 transmission.

Approximately 500 million Europeans use a groundwater source for water consumption on a daily basis. Private (unregulated) groundwater wells are key sources of domestic drinking water in the Republic of Ireland (ROI) with approximately 750,000 users. The distribution of groundwater wells in the ROI is highly concentrated in rural areas in correspondence with the absence of piped infrastructure. The nexus of key (extra-)local factors, including high private groundwater reliance, ubiquity of domestic wastewater treatment systems and pastoral agriculture in rural areas, in conjunction with a temperate maritime climate and distinctive hydro(geo)logical settings, has been linked to a high groundwater susceptibility to contamination and risk of waterborne enteric infection.DESIGN focuses on the incidence and sources of verotoxigenic-producing Escherichia coli (VTEC) and Cryptosporidium spp. – the most prevalent waterborne pathogens inducing enteric illness in the ROI – associated with private groundwater wells. The findings of a systematic literature review focusing on the prevalence of Cryptosporidium in domestic groundwater supplies are presented. Calculated detection rates for groundwater wells (19%) and samples (13%) indicate Cryptosporidium spp. contamination of domestic groundwater supplies is common, representing a latent health risk of direct concern to groundwater consumers and public health authorities. Presented figures provide unprecedented “baselines” highly applicable in groundwater/catchment management and epidemiology (e.g., QMRA). Several knowledge gaps were identified with the lack of standardized reporting among investigations emerging as a key concern.The results of temporal (i.e., repeat) sampling regimes analysing the spatio-temporal incidence of Cryptosporidium and VTEC in groundwater wells are also presented. Sampling locations (n = 80) were geo-referenced and linked to multiple variables (e.g., land-use, agricultural statistics, hydrogeology) compiled in a novel geo-database. In conjunction with supply infrastructural data, relevant risk factors associated with VTEC and Cryptosporidium well contamination were identified. Furthermore, incorporating previously available data from project partners, stochastic QMRA and Environmental Fate Model(s) were produced to assess the relative risk of VTEC well contamination and seasonal influence. The explorative Cryptosporidium sampling regime provides the first national account of (oocyst) incidence in domestic groundwater infrastructure enabling insights into potential environmental sources and (surface-groundwater) transport mechanisms. The results obtained represent a stepping stone towards the development of bespoke groundwater management strategies in the ROI based on the ‘One Health’ concept.

Shiga toxigenic Escherichia coli (STEC) are pathogenic E. coli that cause infectious diarrhoea. In some cases infection may be complicated by renal failure and death. The incidence of human infection with STEC in Ireland is the highest in Europe. The objective of the study was to examine the spatial incidence of human STEC infection in a region of Ireland with significantly higher rates of STEC incidence than the national average and to identify possible risk factors of STEC incidence at area level. Anonymised laboratory records (n = 379) from 2009 to 2015 were obtained from laboratories serving three counties in the West of Ireland. Data included location and sample date. Population and electoral division (ED) data were obtained from the Irish 2011 Census of Population. STEC incidence was calculated for each ED (n = 498) and used to map hotspots/coldspots using the Getis-Ord Gi* spatial statistic and significant spatial clustering using the Anselin's Local Moran's I statistic. Multivariable regression analysis was used to consider the importance of a number of potential predictors of STEC incidence. Incidence rates for the seven-year period ranged from 0 to 10.9 cases per 1000. A number of areas with significant local clustering of STEC incidence as well as variation in the spatial distribution of the two main serogroups associated with disease in the region i.e. O26 and O157 were identified. Cattle density was found to be a statistically significant predictor of STEC in the region. GIS analysis of routine data indicates that cattle density is associated STEC infection in this high incidence region. This finding points to the importance of agricultural practices for human health and the importance of a “one-health” approach to public policy in relation to agriculture, health and environment. Thanks to the Division of Clinical Microbiology for their help in particular Belinda Hanahoe. This work was funded through an Irish Research Council (GOIPD/2015/610) Government of Ireland Postdoctoral Fellowship. Icons in graphical abstract made by Freepik (www.freepik.com) from Flaticon (www.flaticon.com). Flaticon is licensed by Creative Commons BY 3.0. peer-reviewed 2020-05-12

Cryptosporidiosis is one of the leading causes of diarrhoeal illness and mortality induced by protozoan pathogens worldwide. As a largely waterborne disease, emphasis has been given to the study of Cryptosporidium spp. in surface waters, readily susceptible to pathogenic contamination. Conversely, the status of Cryptosporidium in potable groundwater sources, generally regarded as a pristine and "safe" drinking-water supply owing to (sub)-soil protection, remains largely unknown. As such, this investigation presents the first literature review aimed to ascertain the global prevalence of Cryptosporidium in groundwater supply sources intended for human consumption. Thirty-seven peer-reviewed studies were identified and included in the review. Groundwater sample and supply detection rates (estimated 10-20%) indicate Cryptosporidium is frequently present in domestic groundwater sources, representing a latent health concern for groundwater consumers. Specifically, sample (10.4%) and source (19.1%) detection rates deriving from comprehensive "temporal" investigations are put forward as representative of a contamination 'baseline' for Cryptosporidium in 'domestic' groundwater supplies. Proposed 'baseline' prevalence figures are largely applicable in preventive risk-based catchment and groundwater quality management including the formulation of Quantitative Microbial Risk Assessment (QMRA). Notwithstanding, a large geographical disparity in available investigations and lack of standardized reporting restrict the transferability of research findings. Overall, the mechanisms responsible for Cryptosporidium transport and ingress into groundwater supplies remain ambiguous, representing a critical knowledge gap, and denoting a distinctive lack of integration between groundwater and public-health sub-disciplines among investigations. Key recommendations and guidelines are provided for prospective studies directed at more integrative and multi-disciplinary research.

The environmental impact of silver nanoparticles (AgNP) has become a topic of interest recently, this is due to the fact that AgNPs have been included in numerous consumer products including textiles, medical products, domestic appliances, food containers, cosmetics, paints and nano-functionalised plastics. The production, use and disposal of these AgNP containing products are potential routes for environmental exposure. These concerns have led to a number of studies investigating the release of particles from nano-functionalised products, the detection of the particles in the aquatic environment and the potential environmental toxicology of these AgNPs to aquatic organisms. The overall aim of this review is to examine methods for the capture and detection of AgNPs, potential toxicity and transmission routes in the aquatic environment. yes

The rapid dissemination of carbapenemase-producingEnterobacterales(CPE) is a major public health concern. The role that the aquatic environment plays in this dissemination is underexplored. This study aimed to examine seawater as a reservoir for CPE. Seawater sampling took place at a bathing site throughout the 2017 bathing season. Each 30 L sample (n = 6) was filtered using the CapE filtration system. Wastewater samples (200 mL) (pre-treatment (n = 3) and post-treatment (n = 3)) were obtained from a nearby secondary wastewater treatment plant, during the same time period. All samples were examined for CPE. Whole genome sequencing of confirmed CPE was carried out using Illumina sequencing. Isolate genomes were hosted in corresponding BIGSdb databases and analyses were performed using multiple web-based tools. CPE was detected in 2/6 seawater samples. It was not detected in any wastewater samples. OXA-48-like-producing ST131Escherichia coli(Ec_BM707) was isolated from a seawater sample collected in May 2017 and OXA-48-like-producing ST101Klebsiella pneumoniae(Kp_BM758) was isolated from a seawater sample collected in August 2017. The genomes of the environmental isolates were compared to a collection of previously described Irish clinical OXA-48-like-producingEnterobacterales(n = 105). Ec_BM707 and Kp_BM758 harbouredblaOXA-48on similar mobile genetic elements to those identified in the clinical collection (pOXA-48 fragment in Ec_BM707 and IncL(pOXA-48) plasmid in Kp_BM758). Genetic similarities were observed between Ec_BM707 and several of the clinical ST131E. coli,with allele matches at up to 98.2% of 2513 core genome multilocus sequence type (cgMLST) loci. In contrast, Kp_BM758 and the 34 clinicalK. pneumoniaewere genetically distant. The source of the CPE at this site was not identified. The detection of OXA-48-like-producing ST131E. coliand OXA-48-like-producing ST101K. pneumoniaein Irish recreational water is a concern. The potential for contamination of the aquatic environment to contribute to dissemination of CPE in Europe warrants further study.

Antimicrobial resistance (AMR) is one of the leading threats to human health worldwide. The identification of potential sources of antimicrobial resistant organisms (AROs) and their transmission routes in the environment is important for improving our understanding of AMR and to inform and improve policy and monitoring systems, as well as the identification of suitable sampling locations and potential intervention points. This exploratory study uses geographic information systems (GIS) to analyse the spatial distribution of likely ARO sources and transmission routes in four local authority areas (LAAs) in Ireland. A review of relevant spatial data in each LAA, grouped into themes, and categorised into sources and transmission routes, was undertaken. A range of GIS techniques was used to extract, organise, and collate the spatial data into final products in the form of thematic maps for visual and spatial analysis. The results highlight the location of &lsquo, clusters&rsquo, at increased risk of harbouring AMR in each LAA. They also demonstrate the relevance of aquatic transmission routes for ARO mobility and risk of human exposure. The integration of a GIS approach with expert knowledge of AMR is shown to be a useful tool to gain insights into the spatial dimension of AMR and to guide sampling campaigns and intervention points.

Verocytotoxigenic Escherichia coli (VTEC) is associated with a wide spectrum of disease from mild self-limiting diarrhoea to haemolytic uremic syndrome. Contaminated drinking water is accepted as an important route of transmission in Ireland as elsewhere however established methods for detection of VTEC in drinking water have limitations. We describe a sensitive and rapid method for detection of VTEC from large volumes (20 to 30L) of drinking water based on filtration, enrichment culture of filters and real-time PCR detection of VTEC virulence and O antigen determinants from enrichments. The method has potential applications for other waterborne pathogens.

Animal manures and food wastes are significant reservoirs of antimicrobial resistant bacteria, among which carbapenemase-producing Enterobacterales (CPE) are resistant to almost all antibiotics and have been detected in these wastes. This study investigated the inactivation of three different CPE strains (KPC-3, OXA-48 and NDM-1 carbapenemase-producing Klebsiella pneumoniae) during anaerobic co-digestion of food waste and pig manure at various total solids (TS) contents. The results showed that the elimination of CPE strains was more efficient at higher TS contents. While increasing the TS contents from 5% to 20%, the survival time of CPE decreased from 9 days to 2 days. Statistical analysis revealed significant negative correlations between total volatile fatty acids (VFAs) and the survival time of two CPE strains (KPC-3 and OXA-48 producing Klebsiella pneumoniae) (P

SUMMARYIn October 2012, an outbreak of gentamicin-resistant, ciprofloxacin non-susceptible extended-spectrumβ-lactamase (ESBL)-producingKlebsiella pneumoniaeoccurred in a neonatal intensive care unit in Ireland. In order to determine whether the outbreak strain was more widely dispersed in the country, 137 isolates ofK. pneumoniaewith this resistance phenotype collected from 17 hospitals throughout Ireland between January 2011 and July 2013 were examined. ESBL production was confirmed phenotypically and all isolates were screened for susceptibility to 19 antimicrobial agents and for the presence of genes encodingblaTEM,blaSHV,blaOXA, andblaCTX-M; 22 isolates were also screened forblaKPC,blaNDM,blaVIM,blaIMPandblaOXA-48genes. All isolates harbouredblaSHVandblaCTX-Mand were resistant to ciprofloxacin, gentamicin, nalidixic acid, amoxicillin-clavulanate, and cefpodoxime; 15 were resistant to ertapenem, seven to meropenem and five isolates were confirmed as carbapenemase producers. Pulsed-field gel electrophoresis of all isolates identified 16 major clusters, with two clusters comprising 61% of the entire collection. Multilocus sequence typing of a subset of these isolates identified a novel type, ST1236, a single locus variant of ST48. Data suggest that two major clonal groups, ST1236/ST48 (CG43) and ST15/ST14 (CG15) have been circulating in Ireland since at least January 2011.

In 2007, a waterborne outbreak of Cryptosporidium hominis infection occurred in western Ireland, resulting in 242 laboratory-confirmed cases and an uncertain number of unconfirmed cases. A boil water notice was in place for 158 days that affected 120,432 persons residing in the area, businesses, visitors, and commuters. This outbreak represented the largest outbreak of cryptosporidiosis in Ireland. The purpose of this study was to evaluate the cost of this outbreak. We adopted a societal perspective in estimating costs associated with the outbreak. Economic cost estimated was based on totaling direct and indirect costs incurred by public and private agencies. The cost of the outbreak was estimated based on 2007 figures. We estimate that the cost of the outbreak was approximate to(sic)19 million (approximate to(sic)120,000/day of the outbreak). The US dollar equivalent based on today's exchange rates would be $22.44 million (approximate to$142,000/day of the outbreak). This study highlights the economic need for a safe drinking water supply.

In this study, New Delhi metallo-beta-lactamase (NDM)-producing Enterobacteriaceae were identified in Irish recreational waters and sewage. Indistinguishable NDM-producing Escherichia coli by pulsed-field gel electrophoresis were isolated from sewage, a fresh water stream and a human source. NDM-producing Klebsiella pneumoniae isolated from sewage and seawater in the same area were closely related to each other and to a human isolate. This raises concerns regarding the potential for sewage discharges to contribute to the spread of carbapenemase-producing Enterobacteriaceae.

The prevalence of antimicrobial resistant (AMR) bacteria is increasing worldwide and remains a significant medical challenge which may lead to antimicrobial redundancy. The contribution of hospital effluent to the prevalence of resistance in wastewater treatment plant (WWTP) effluents is not fully understood. AMR bacteria contained in hospital effluent may be released into the aquatic and soil environments after WWTP processing. Hence, the objective of this study is to identify the extent hospital effluent contributes to contamination of these environments by comparing two WWTPs, one which receives hospital effluent and one which does not. AMR Escherichia coli were monitored in the two WWTPs. A model was developed using these monitored values to predict the effect of hospital effluent within a WWTP. The model predicted levels of AMR E. coli in the aquatic environment and potential bather exposure to AMR E. coli. The model results were highly variable. WWTP influent containing hospital effluent had a higher mean percentage of AMR E. coli; although, there appeared to be no within treatment plant effect on the prevalence of AMR E. coli. Examination of WWTP sludge showed a similar variation. There appeared to be no consistent effect from the presence of hospital effluent. The human exposure assessment model predicted swimmer intake of AMR E. coli between 6 and 193CFU/100ml sea water. It appears that hospital effluent is not the main contributing factor behind the development and persistence of AMR E. coli within WWTPs, although resistance may be too well-developed to identify an influence from hospital effluent. Mitigation needs to focus on the removal of already present resistant bacteria but for new or hospital specific antimicrobials focus needs to be on their limited release within effluents or separate treatment.

The extent hospital effluent contributes to antimicrobial presence in the environment and its impact on resistance dissemination remains unknown. To investigate the fate of the antimicrobial ciprofloxacin in hospital effluent a Monte Carlo simulation model was developed to model levels from hospital use to wastewater treatment plant (WWTP) effluent release, in addition to modeling resistance formation potential, hazard quotient (HQ) and swimmer exposure. The mean predicted concentration (PC) of ciprofloxacin in hospital effluent, urban effluent, WWTP effluent, sludge, soil and sea water was 579, 6.06, 2.59, 3.48, 0.006 and 0.15 mg/m(3), respectively. A parallel surveillance study confirmed levels of ciprofloxacin above or below the limit of detection. The model predicted levels would never exceed the ECOSAR toxicity value. The model predicted a 98% probability of ciprofloxacin exhibiting a HQ1 (low toxicity concern). The mean ciprofloxacin PC in WWTP effluent was less than the minimum inhibitory concentration (MIC). The probability of conditions in WWTP effluent being favorable for resistance at 20% and 80% of the MIC was 3% and 72%, respectively. In all instances, when the MIC was bound, the probability for resistance formation within soil and sea water was1%. The probability of a swimmer being exposed to a level of ciprofloxacin greater than the acceptable daily intake was negligible. The study concluded that release of hospital effluent into the environment may lead to concentrations of ciprofloxacin which are of low toxicity concern but may be conducive to resistance formation and allow for the dissemination of resistance.

Foodborne pathogens can attach to, and survive on, food contact surfaces for long periods by forming a biofilm. Salmonella enterica is the second most common cause of foodborne illness in Ireland. The ability of S. enterica to form a biofilm could contribute to its persistence in food production areas, leading to cross-contamination of products and surfaces. Arising from a large foodborne outbreak of S. enterica serovar Agona associated with a food manufacturing environment, a hypothesis was formulated that the associated Salmonella Agona strain had an enhanced ability to form a biofilm relative to other S. enterica. To investigate this hypothesis, 12 strains of S. enterica, encompassing three S. enterica serovars, were assessed for the ability to form a biofilm on multiple food contact surfaces. All isolates formed a biofilm on the contact surfaces, and there was no consistent trend for the Salmonella Agona outbreak strain to produce a denser biofilm compared with other strains of Salmonella Agona or Salmonella Typhimurium. However, Salmonella Enteritidis biofilm was considerably less dense than Salmonella Typhimurium and Salmonella Agona biofilms. Biofilm density was greater on tile than on concrete, polycarbonate, stainless steel, or glass.

Phylogeny of CC22 MRSA in the Cambridge LTCF with bootstrap values. Bootstrap values for branches are shown in grey. (PDF 224 kb)

Phylogeny of CC5 MRSA in the Galway study. Maximum likelihood tree generated from core genome SNPs of CC5 MRSA isolates from the Galway LTCF residents (blue) and isolates from Galway University Hospital (red). Bootstrap values for branches are shown in grey. (PDF 266 kb)

Objectives To describe an outbreak of KPC-2-producing Klebsiella pneumoniae with inter-hospital spread and measures taken to control transmission. Methods Between January and March 2011, 13 K. pneumoniae isolates were collected from nine patients at hospital A and two patients at hospital B. Meropenem, imipenem and ertapenem MICs were determined by Etest, carbapenemase production was confirmed by the modified Hodge method and by a disc synergy test, and confirmed carbapenemase producers were tested for the presence of carbapenemase-encoding genes by PCR. PFGE, plasmid analysis, multilocus variable-number tandem-repeat analysis (MLVA) and multilocus sequence typing (MLST) analysis were performed on all or a subset of isolates. Results Meropenem, imipenem and ertapenem MICs were 4 to >32, 8-32 and >16 mg/L, respectively. PCR and sequencing confirmed the presence of bla(KPC-2). PFGE identified four distinguishable (≥88%) pulsed-field profiles (PFPs). Isolates distinguishable by PFGE had identical MLVA profiles, and MLST analysis indicated all isolates belonged to the ST258 clone. Stringent infection prevention and control measures were implemented. Over a period of almost 8 months no further carbapenemase-producing Enterobacteriaceae (CPE) were isolated. However, KPC-2-producing K. pneumoniae was detected in two further patients in hospital A in August (PFP indistinguishable from previous isolates) and October 2011 (PFP similar to but distinguishable from previous isolates). Conclusions Stringent infection prevention and control measures help contain CPE in the healthcare setting; however, in the case of hospital A, where CPE appears to be established in the population served, it may be virtually impossible to achieve eradication or avoid reintroduction into the hospital.

Salmonella enterica ( S . Typhimurium) strains from Kenya, Malawi, and Ireland showing elevated cefepime MIC values carried bla OXA-1 . These strains were not detected by current guidelines for extended-spectrum β-lactamase production based on MIC values or clavulanate inhibition, since cefepime is a preferred substrate for OXA-1 and this enzyme is reported to be resistant to clavulanate inhibition. bla OXA-1 was located within a class I integron and an activated P 2 promoter was identified upstream of bla OXA-1 . P 2 was activated by the insertion of a triplet ‘GGG' upstream of the −10 signal. All African strains were ST313, prevalent in this continent, and the Irish isolate belonged to ST19.

Animals represent potential reservoirs for the dissemination of antimicrobial resistance. Twenty domestically produced chicken meat samples were collected from 19 retail outlets in Ireland, inoculated into Bolton broth and cultured on modified charcoal cefoperazone deoxycholate (mCCDA) and Preston agars. Selected representative coliforms included 16 E.coli and 4 Pseudomonas aeruginosa. All E.coli isolates were confirmed as ESBL producers, 15 isolates harbored a blaCTX-M group-1 gene, and none belonged to the E.coli 025b:H4-ST131 clonal group. Pulsed field gel electrophoresis (PFGE) analysis identified 13 distinct pulsed field profiles and comparison with more than 300 human clinical isolates of ESBL producing E. coli did not reveal any similarities. ESBL producing E. coli were detected on retail meats in the Irish market place. Although no similarity was apparent between poultry and human isolates this does not preclude a role for ESBL-producing E.coli in meat in dissemination of antimicrobial resistance.