Removal of AMR plasmids using a mobile, broad host-range CRISPR-Cas9 delivery tool.

Antimicrobial resistance (AMR) genes are widely disseminated on plasmids. Therefore, interventions aimed at blocking plasmid uptake and transfer may curb the spread of AMR. Previous studies have used CRISPR-Cas-based technology to remove plasmids encoding AMR genes from target bacteria, using either phage- or plasmid-based delivery vehicles that typically have narrow host ranges. To make this technology feasible for removal of AMR plasmids from multiple members of complex microbial communities, an efficient, broad host-range delivery vehicle is needed. We engineered the broad host-range IncP1-plasmid pKJK5 to encode cas9 programmed to target an AMR gene. We demonstrate that the resulting plasmid pKJK5::csg has the ability to block the uptake of AMR plasmids and to remove resident plasmids from Escherichia coli. Furthermore, due to its broad host range, pKJK5::csg successfully blocked AMR plasmid uptake in a range of environmental, pig- and human-associated coliform isolates, as well as in isolates of two species of Pseudomonas. This study firmly establishes pKJK5::csg as a promising broad host-range CRISPR-Cas9 delivery tool for AMR plasmid removal, which has the potential to be applied in complex microbial communities to remove AMR genes from a broad range of bacterial species.

Toward a Universal Unit for Quantification of Antibiotic Resistance Genes in Environmental Samples.

Surveillance of antibiotic resistance genes (ARGs) has been increasingly conducted in environmental sectors to complement the surveys in human and animal sectors under the "One-Health" framework. However, there are substantial challenges in comparing and synthesizing the results of multiple studies that employ different test methods and approaches in bioinformatic analysis. In this article, we consider the commonly used quantification units (ARG copy per cell, ARG copy per genome, ARG density, ARG copy per 16S rRNA gene, RPKM, coverage, PPM, etc.) for profiling ARGs and suggest a universal unit (ARG copy per cell) for reporting such biological measurements of samples and improving the comparability of different surveillance efforts.

Uncovering the prevalence and drivers of antibiotic resistance genes in soils across different land-use types.

The emergence and spread of antibiotic resistance genes (ARGs) in soil due to animal excreta and organic waste is a major threat to human health and ecosystems, and global efforts are required to tackle the issue. However, there is limited knowledge of the variation in ARG prevalence and diversity resulting from different land-use patterns and underlying driving factors in soils. This study aimed to comprehensively characterize the profile of ARGs and mobile genetic elements and their drivers in soil samples collected from 11 provinces across China, representing three different land-use types, using high-throughput quantitative polymerase chain reaction and 16S rRNA amplicon sequencing. Our results showed that agricultural soil had the highest abundance and diversity of ARGs, followed by tea plantation and forest land. A total of 124 unique ARGs were detected in all samples, with shared subtypes among different land-use patterns indicating a common origin or high transmission frequency. Moreover, significant differences in ARG distribution were observed among different geographical regions, with the greatest enrichment of ARGs found in southern China. Biotic and abiotic factors, including soil properties, climatic factors, and bacterial diversity, were identified as the primary drivers associated with ARG abundance, explaining 71.8% of total ARG variation. The findings of our study demonstrate that different land-use patterns are associated with variations in ARG abundance in soil, with agricultural practices posing the greatest risk to human health and ecosystems regarding ARGs. Our identification of biotic and abiotic drivers of ARG abundance provides valuable insights into strategies for mitigating the spread of these genes. This study emphasizes the need for coordinated and integrated approaches to address the global antimicrobial resistance crisis.

Why don't the British eat locally harvested shellfish? The role of misconceptions and knowledge gaps.

Although the UK consumes a substantial amount of shellfish, most is imported (e.g. prawns), while locally harvested molluscs and crustaceans (e.g. mussels, crab) tend to be exported. This study aimed to investigate whether a low rate of local shellfish consumption in the UK is due to misunderstandings or knowledge gaps about the potential health and environmental risks and benefits of consumption. Following the Mental Models Approach, the present paper reveals: 1) qualitative results from 26 stakeholder/public interviews which identified 10 key misunderstandings and knowledge gaps, including incorrect beliefs about health risks and a lack of knowledge about the relative environmental benefits compared to other foods (key misunderstandings included some parts of a crab are poisonous if eaten, and the majority of UK shellfish is farmed), and 2) quantitative results from a survey (n = 1,433) that explored the degree to which these misunderstandings and knowledge gaps may influence consumption intentions in the wider UK population. Survey results suggested the number of misunderstandings and knowledge gaps significantly predicted shellfish consumption intentions even after controlling for demographics, food related values, and past consumption behaviour. Path analyses revealed their impact on intentions was partially mediated via Theory of Planned Behaviour variables. Results could inform information campaigns supporting consumers to make more informed decisions regarding a group of foods that are potentially both healthy and relatively environmentally friendly.

Staphylococcus cornubiensis sp. nov., a member of the Staphylococcus intermedius Group (SIG).

We here describe a novel species in the Staphylococcus intermedius Group (SIG) which is phenotypically similar to Staphylococcus pseudintermedius but is genomically distinct from it and other SIG members, with an average nucleotide identity of 90.2 % with its closest relative S. intermedius. The description of Staphylococcus cornubiensis sp. nov. is based on strain NW1T (=NCTC 13950T=DSM 105366T) isolated from a human skin infection in Cornwall, UK. Although pathogenic, NW1T carries no known virulence genes or mobilizable antibiotic resistance genes and further studies are required to assess the prevalence of this species in humans as well as its potential presence in companion animals.

Developing a local antimicrobial resistance action plan: the Cornwall One Health Antimicrobial Resistance Group.

Objectives: The UK Five Year Antimicrobial Resistance (AMR) Strategy was published in September 2013 and recommended a One Health approach emphasizing the importance of collaboration to tackle AMR. We describe the inauguration of what we believe to be the first regional One Health group established in the UK. The purpose of the group was to ensure the implementation of a coordinated Cornwall-wide response to the UK AMR Strategy and we describe the outputs of the group to date. Methods: The Cornwall Antimicrobial Resistance Group was set up as a sub-group of the Health & Wellbeing Board's Health Protection Committee. Stakeholders reviewed the key objectives set out within the Five Year AMR strategy, identified local priorities and existing work streams within Cornwall, and completed a gap analysis. The annual work plan was developed from the gap analysis and provided a foundation for improved coordination of One Health antimicrobial stewardship (AMS) activity in Cornwall. Results: To date, outputs from the group can be arranged under the following themes: education and engagement with the public; education and engagement with healthcare workers and veterinarians; and a comprehensive AMS programme for all sectors. The group continues to grow in size with wider stakeholder engagement and increased variety of work streams. Conclusions: This unique group facilitates discussions across sectors, which has enabled the sharing of knowledge, ideas and resources, stimulated local AMS initiatives, and ensured a platform for the development of future AMR and AMS work.

Wild small mammals as sentinels for the environmental transmission of antimicrobial resistance.

Antimicrobial resistance (AMR) represents a serious threat to human health worldwide. We have tested the use of free-living small mammals (mice, voles and shrews) as sentinels of variation in the distribution of AMR in the environment and the potential for transmission from the natural environment to animal hosts. Escherichia coli isolated from the faeces of small mammals trapped at paired coastal and inland sites were tested for resistance to four antibiotics: trimethoprim, ampicillin, ciprofloxacin and cefotaxime. Coastal individuals were over twice as likely to carry AMR E. coli than inland individuals (79% and 35% respectively), and both between-site and between-species variation was observed. Animals from coastal populations also excreted increased numbers of AMR E. coli and a greater diversity of E. coli phylotypes, including human-associated pathogenic strains. Small mammals appear to be useful bioindicators of fine-scale spatial variation in the distribution of AMR and, potentially, of the risks of AMR transmission to mammalian hosts, including humans.

Evaluating the Mental Models Approach to Developing a Risk Communication: A Scoping Review of the Evidence.

Risk communication is fundamental in ensuring people are equipped with the knowledge needed to navigate varied risks. One generally well-regarded framework for the development of such communications is the mental models approach to risk communication (MMARC). Developed during the 1990s, the MMARC has been applied to a range of health, technological, and environmental risks. However, as yet, we know of no attempt to collate and review articles that evaluated communications developed using the MMARC. This article took a first step at addressing this gap by conducting a scoping review that aimed to begin to explore the fidelity with which the approach has been applied, explore whether there appeared to be sufficient studies to warrant a future systematic review, and identify future research questions. Although the initial search found over 100 articles explicitly applying the MMARC, only 12 of these developed a risk-related communication that was tested against a control (and thus included in the current review). All studies reported a positive effect of the MMARC versus control communication for at least some of the outcome measures (knowledge being the most prevalent). However, there was wide variation between studies including type of control, outcomes assessed, and only five studies reported adopting a randomized design. The review highlights both the need for greater fidelity in the way future studies operationalize the MMARC approach, and suggests that a full-scale systematic review of the MMARC literature appears justified, especially given the possibility of a large gray literature in this area.

Structural and Biochemical Characterization of Rm3, a Subclass B3 Metallo-ß-Lactamase Identified from a Functional Metagenomic Study.

ß-Lactamase production increasingly threatens the effectiveness of ß-lactams, which remain a mainstay of antimicrobial chemotherapy. New activities emerge through both mutation of previously known ß-lactamases and mobilization from environmental reservoirs. The spread of metallo-ß-lactamases (MBLs) represents a particular challenge because of their typically broad-spectrum activities encompassing carbapenems, in addition to other ß-lactam classes. Increasingly, genomic and metagenomic studies have revealed the distribution of putative MBLs in the environment, but in most cases their activity against clinically relevant ß-lactams and, hence, the extent to which they can be considered a resistance reservoir remain uncharacterized. Here we characterize the product of one such gene, blaRm3, identified through functional metagenomic sampling of an environment with high levels of biocide exposure. blaRm3 encodes a subclass B3 MBL that, when expressed in a recombinant Escherichia coli strain, is exported to the bacterial periplasm and hydrolyzes clinically used penicillins, cephalosporins, and carbapenems with an efficiency limited by high Km values. An Rm3 crystal structure reveals the MBL superfamily αß/ßα fold, which more closely resembles that in mobilized B3 MBLs (AIM-1 and SMB-1) than other chromosomal enzymes (L1 or FEZ-1). A binuclear zinc site sits in a deep channel that is in part defined by a relatively extended N terminus. Structural comparisons suggest that the steric constraints imposed by the N terminus may limit its affinity for ß-lactams. Sequence comparisons identify Rm3-like MBLs in numerous other environmental samples and species. Our data suggest that Rm3-like enzymes represent a distinct group of B3 MBLs with a wide distribution and can be considered an environmental reservoir of determinants of ß-lactam resistance.

Improved detection of Staphylococcus intermedius group in a routine diagnostic laboratory.

The Staphylococcus intermedius group (SIG) includes zoonotic pathogens traditionally associated with dog bites. We describe a simple scheme for improved detection of SIG using routine laboratory methods, report its effect on isolation rates, and use sequencing to confirm that, apart from one atypical SIG strain, most isolates are Staphylococcus pseudintermedius.

Performance of a Noninvasive Test for Detecting Mycobacterium bovis Shedding in European Badger (Meles meles) Populations.

The incidence of Mycobacterium bovis, the causative agent of bovine tuberculosis, in cattle herds in the United Kingdom is increasing, resulting in substantial economic losses. The European badger (Meles meles) is implicated as a wildlife reservoir and is the subject of control measures aimed at reducing the incidence of infection in cattle populations. Understanding the epidemiology of M. bovis in badger populations is essential for directing control interventions and understanding disease spread; however, accurate diagnosis in live animals is challenging and currently uses invasive methods. Here we present a noninvasive diagnostic procedure and sampling regimen using field sampling of latrines and detection of M. bovis with quantitative PCR tests, the results of which strongly correlate with the results of immunoassays in the field at the social group level. This method allows M. bovis infections in badger populations to be monitored without trapping and provides additional information on the quantities of bacterial DNA shed. Therefore, our approach may provide valuable insights into the epidemiology of bovine tuberculosis in badger populations and inform disease control interventions.

Microcosm experiment investigating climate-induced thermal effects on human virus viability in seawater: qPCR vs capsid integrity for enhanced risk management.

Climate change is intensifying extreme weather events in coastal areas, leading to more frequent discharge of untreated wastewater containing human viruses into coastal waters. This poses a health risk, especially during heatwaves when bathing activity increases. A study examined the survival and viability of seven common wastewater viruses in seawater at different temperatures. Viral genomes were quantified using direct qPCR, whilst viability was assessed using Capsid Integrity qPCR. Results showed that T90 values from direct qPCR were much higher than those from CI-qPCR, suggesting that risk mitigation should be based on viral integrity tests. All viruses remained potentially viable for at least 72 h in environmental seawater and longer in sterile artificial seawater, highlighting the importance of biotic processes in viral inactivation. Viral persistence decreased with increasing temperature. Whilst heatwaves may partially reduce risks from human viral pathogens in coastal waters, they do not eliminate them entirely.

Opportunities and challenges in antimicrobial resistance policy including animal production systems and humans across stakeholders in Argentina: a context and qualitative analysis.

INTRODUCTION: Gaps in antimicrobial resistance (AMR) surveillance and control, including implementation of national action plans (NAPs), are evident internationally. Countries' capacity to translate political commitment into action is crucial to cope with AMR at the human-animal-environment interface. METHODS: We employed a two-stage process to understand opportunities and challenges related to AMR surveillance and control at the human-animal interface in Argentina. First, we compiled the central AMR policies locally and mapped vital stakeholders around the NAP and the national commission against bacterial resistance. Second, we conducted qualitative interviews using a semistructured questionnaire covering stakeholders' understanding and progress towards AMR and NAP. We employed a mixed deductive-inductive approach and used the constant comparative analysis method. We created categories and themes to cluster subthemes and determined crucial relationships among thematic groups. RESULTS: Crucial AMR policy developments have been made since 1969, including gradually banning colistin in food-producing animals. In 2023, a new government decree prioritised AMR following the 2015 NAP launch. Our qualitative analyses identified seven major themes for tackling AMR: (I) Cultural factors and sociopolitical country context hampering AMR progress, (II) Fragmented governance, (III) Antibiotic access and use, (IV) AMR knowledge and awareness throughout stakeholders, (V) AMR surveillance, (VI) NAP efforts and (VII) External drivers. We identified a fragmented structure of the food production chain, poor cross-coordination between stakeholders, limited surveillance and regulation among food-producing animals and geographical disparities over access, diagnosis and treatment. The country is moving to integrate animal and food production into its surveillance system, with most hospitals experienced in monitoring AMR through antimicrobial stewardship programmes. CONCLUSION: AMR accountability should involve underpinning collaboration at different NAP implementation levels and providing adequate resources to safeguard long-term sustainability. Incorporating a multisectoral context-specific approach relying on different One Health domains is crucial to strengthening local AMR surveillance.

A critical meta-analysis of predicted no effect concentrations for antimicrobial resistance selection in the environment.

Antimicrobial resistance (AMR) is one of the greatest threats to human health with a growing body of evidence demonstrating that selection for AMR can occur at environmental antimicrobial concentrations. Understanding the concentrations at which selection for resistance may occur is critical to help inform environmental risk assessments and highlight where mitigation strategies are required. A variety of experimental and data approaches have been used to determine these concentrations. However, there is minimal standardisation of existing approaches and no consensus on the relative merits of different methods. We conducted a semi-systematic literature review to collect and critically appraise available minimal selective concentration (MSC) and predicted no effect concentration for resistance (PNECR) data and the approaches used to derive them. There were 21 relevant articles providing 331 selective concentrations, ranging from 0.00087 µg/L (ciprofloxacin) to 2000 µg/L (carbenicillin). Meta-analyses of these data found that selective concentrations are highly compound-dependent, and only a subset of all antimicrobials have been the focus of most of the research. The variety of approaches that have been used, knowledge gaps and future research priorities were identified, as well as recommendations for those considering the selective risks of antimicrobials in the environment.

The scourge of antibiotic resistance: the important role of the environment.

Antibiotic resistance and associated genes are ubiquitous and ancient, with most genes that encode resistance in human pathogens having originated in bacteria from the natural environment (eg, ß-lactamases and fluoroquinolones resistance genes, such as qnr). The rapid evolution and spread of "new" antibiotic resistance genes has been enhanced by modern human activity and its influence on the environmental resistome. This highlights the importance of including the role of the environmental vectors, such as bacterial genetic diversity within soil and water, in resistance risk management. We need to take more steps to decrease the spread of resistance genes in environmental bacteria into human pathogens, to decrease the spread of resistant bacteria to people and animals via foodstuffs, wastes and water, and to minimize the levels of antibiotics and antibiotic-resistant bacteria introduced into the environment. Reducing this risk must include improved management of waste containing antibiotic residues and antibiotic-resistant microorganisms.

Influence of humans on evolution and mobilization of environmental antibiotic resistome.

The clinical failure of antimicrobial drugs that were previously effective in controlling infectious disease is a tragedy of increasing magnitude that gravely affects human health. This resistance by pathogens is often the endpoint of an evolutionary process that began billions of years ago in non-disease-causing microorganisms. This environmental resistome, its mobilization, and the conditions that facilitate its entry into human pathogens are at the heart of the current public health crisis in antibiotic resistance. Understanding the origins, evolution, and mechanisms of transfer of resistance elements is vital to our ability to adequately address this public health issue.

Functional metagenomic libraries generated from anthropogenically impacted environments reveal importance of metabolic genes in biocide and antibiotic resistance.

Anthropogenic activities result in the release of antimicrobial resistant bacteria and a cocktail of antimicrobial compounds into the environment that may directly select or indirectly co-select for antimicrobial resistance (AMR). Many studies use metagenome sequencing or qPCR-based approaches to study the environmental resistome but these methods are limited by a priori knowledge. In this study, a functional metagenomic approach was used to explore biocide resistance mechanisms in two contaminated environments and a pristine site, and to identify whether potentially novel genes conferring biocide resistance also conferred resistance or reduced susceptibility to antibiotics. Resistance was predominately mediated through novel mechanisms exclusive of the well-known qac efflux genes. UDP-galactose 4-epimerase (galE) -like genes were identified in both contaminated environments and were shown to confer cross-resistance to biocides and clinically important antibiotics for the first time (to our knowledge), compared to knockout mutants. GalE -like genes were also co-located with transposons, suggesting mobilisation potential. These results show that housekeeping genes may play a significant yet underappreciated role in AMR in environmental microbiomes.

The effect of metal remediation on the virulence and antimicrobial resistance of the opportunistic pathogen Pseudomonas aeruginosa.

Anthropogenic metal pollution can result in co-selection for antibiotic resistance and potentially select for increased virulence in bacterial pathogens. Metal-polluted environments can select for the increased production of siderophore molecules to detoxify non-ferrous metals. However, these same molecules also aid the uptake of ferric iron, a limiting factor for within-host pathogen growth, and are consequently a virulence factor. Anthropogenic methods to remediate environmental metal contamination commonly involve amendment with lime-containing materials. However, whether this reduces in situ co-selection for antibiotic resistance and siderophore-mediated virulence remains unknown. Here, using microcosms containing non-sterile metal-contaminated river water and sediment, we test whether liming reduces co-selection for these pathogenicity traits in the opportunistic pathogen Pseudomonas aeruginosa. To account for the effect of environmental structure, which is known to impact siderophore production, microcosms were incubated under either static or shaking conditions. Evolved P. aeruginosa populations had greater fitness in the presence of toxic concentrations of copper than the ancestral strain and showed increased resistance to the clinically relevant antibiotics apramycin, cefotaxime and trimethoprim, regardless of lime addition or environmental structure. Although we found virulence to be significantly associated with siderophore production, neither virulence nor siderophore production significantly differed between the four treatments. Furthermore, liming did not mitigate metal-imposed selection for antibiotic resistance or virulence in P. aeruginosa. Consequently, metal-contaminated environments may select for antibiotic resistance and virulence traits even when treated with lime.

Interspecific competition can drive plasmid loss from a focal species in a microbial community.

Plasmids are key disseminators of antimicrobial resistance genes and virulence factors, and it is therefore critical to predict and reduce plasmid spread within microbial communities. The cost of plasmid carriage is a key metric that can be used to predict plasmids' ecological fate, and it is unclear whether plasmid costs are affected by growth partners in a microbial community. We carried out competition experiments and tracked plasmid maintenance using a model system consisting of a synthetic and stable five-species community and a broad host-range plasmid, engineered to carry different payloads. We report that both the cost of plasmid carriage and its long-term maintenance in a focal strain depended on the presence of competitors, and that these interactions were species specific. Addition of growth partners increased the cost of a high-payload plasmid to a focal strain, and accordingly, plasmid loss from the focal species occurred over a shorter time frame. We propose that the destabilising effect of interspecific competition on plasmid maintenance may be leveraged in clinical and natural environments to cure plasmids from focal strains.