The ability to fight bacterial infections with antibiotics has been a longstanding cornerstone of modern medicine. However, wide-spread overuse and misuse of antibiotics has led to unintended consequences, which in turn require large-scale changes of policy for mitigation. In this review, we address two broad classes of corollaries of antibiotics overuse and misuse. Firstly, we discuss the spread of antibiotic resistance from hotspots of resistance evolution to the environment, with special concerns given to potential vectors of resistance transmission. Secondly, we outline the effects of antibiotic pollution independent of resistance evolution on natural microbial populations, as well as invertebrates and vertebrates. We close with an overview of current regional policies tasked with curbing the effects of antibiotics pollution and outline areas in which such policies are still under development.

Lakes play a pivotal role in ecological and biogeochemical processes and have been described as “sentinels” of environmental change. Assessing “lake health” across large geographic scales is critical to predict the stability of their ecosystem services and their vulnerability to anthropogenic disturbances. The LakePulse research network is tasked with the assessment of lake health across gradients of land use on a continental scale. Bacterial communities are an integral and rapidly responding component of lake ecosystems, yet large-scale responses to anthropogenic activity remain elusive. Here, we assess the ecological impact of land use on bacterial communities from over 200 lakes covering more than 660,000 km² across Eastern Canada. In addition to community variation between ecozones, land use across Eastern Canada also appeared to alter diversity, community composition, and network structure. Specifically, increasing anthropogenic impact within the watershed lowered diversity. Likewise, community composition was significantly correlated with agriculture and urban development within a watershed. Interaction networks showed decreasing complexity and fewer keystone taxa in impacted lakes. Moreover, we identified potential indicator taxa of high or low lake water quality. Together, these findings point to detectable bacterial community changes of largely unknown consequences induced by human activity within lake watersheds.

Freshwater lakes are experiencing rapid changes under accelerated anthropogenic stress and a warming climate. Microorganisms underpin aquatic food webs, yet little is known about how freshwater microbial communities are responding to human impact.

Wastewater-based surveillance (WBS) is an important epidemiological and public health tool for tracking pathogens across the scale of a building, neighbourhood, city, or region. WBS gained widespread adoption globally during the SARS-CoV-2 pandemic for estimating community infection levels by qPCR. Sequencing pathogen genes or genomes from wastewater adds information about pathogen genetic diversity, which can be used to identify viral lineages (including variants of concern) that are circulating in a local population. Capturing the genetic diversity by WBS sequencing is not trivial, as wastewater samples often contain a diverse mixture of viral lineages with real mutations and sequencing errors, which must be deconvoluted computationally from short sequencing reads. In this study we assess nine different computational tools that have recently been developed to address this challenge. We simulated 100 wastewater sequence samples consisting of SARS-CoV-2 BA.1, BA.2, and Delta lineages, in various mixtures, as well as a Delta–Omicron recombinant and a synthetic ‘novel’ lineage. Most tools performed well in identifying the true lineages present and estimating their relative abundances and were generally robust to variation in sequencing depth and read length. While many tools identified lineages present down to 1 % frequency, results were more reliable above a 5 % threshold. The presence of an unknown synthetic lineage, which represents an unclassified SARS-CoV-2 lineage, increases the error in relative abundance estimates of other lineages, but the magnitude of this effect was small for most tools. The tools also varied in how they labelled novel synthetic lineages and recombinants. While our simulated dataset represents just one of many possible use cases for these methods, we hope it helps users understand potential sources of error or bias in wastewater sequencing analysis and to appreciate the commonalities and differences across methods.

Objective: To assess the burden of illness and health care resource utilization of adult nonpsychotic psychiatric outpatients with attention-deficit/hyperactivity disorder (ADHD) in Europe. Methods: This was a multicountry, cross-sectional, observational study where unselected routine patients from clinical psychiatric outpatient settings were screened and assessed for ADHD. Patients were evaluated using the Clinical Global Impressions of Severity (CGI-S) scale, the Sheehan Disability Scale (SDS), and the EuroQol-5 Dimensions questionnaire. Data on comorbidities, functional impairment, and health care resource utilization were captured. Results: The study enrolled 2284 patients, of whom 1986 completed the study. The prevalence of ADHD was 17.4%, of whom 46.0% had a previous ADHD diagnosis. Patients with ADHD had a high clinical burden with psychiatric comorbidities, especially depression (43.0%) and anxiety disorders (36.4%). Substance abuse (9.2% vs. 3.4%) and alcohol abuse (10.3% vs. 5.2%) were more common in the ADHD cohort vs. the non-ADHD cohort. Only 11.5% of the patients with ADHD had no other psychiatric disorder. Various measures indicated a significantly poorer level of functioning for patients with ADHD than without ADHD, as indicated by higher scores for CGI-S (3.8 vs. 3.3) and SDS (18.9 vs. 11.6) and higher percentages of debt (35.5% vs. 24.3%) and criminality (13.8% vs. 6.1%). Lastly, the health care resource utilization was considerable and similar between adult psychiatric outpatients diagnosed and not diagnosed with ADHD. Conclusions: Although care was taken when choosing the sites for this study, to make it representative of the general outpatient adult psychiatric population, caution should be advised in generalizing the findings of our study to the general ADHD or psychiatric outpatient population. This was an observational study, thus no inference on causality can be drawn. Having ADHD imposes a considerable health and social burden on patient and health care resource utilization comparable to other chronic psychiatric disorders.

Our decreasing ability to fight bacterial infections is a major health concern. It is arising due to the evolution of antimicrobial resistance (AMR) in response to the mis- and overuse of antibiotics in both human and veterinary medicine. Lakes integrate watershed processes and thus may act as receptors and reservoirs of antibiotic resistance genes (ARGs) introduced into the watershed by human activities. The resistome – the diversity of ARGs – under varying anthropogenic watershed pressures has been previously studied either focused on few select genes or few lakes. Here, we link the resistome of ~350 lakes sampled across Canada to human watershed activity, trophic status, as well as point sources of ARG pollution including wastewater treatment plants and hospitals in the watershed. A high percentage of the resistance genes detected was either unimpacted by human activity or highly prevalent in pristine lakes, highlighting the role of AMR in microbial ecology in aquatic systems, as well as a pool of genes available for potential horizontal gene transfer to pathogenic species. Nonetheless, watershed agricultural and pasture area significantly impacted the resistome. Moreover, the number of hospitals and the population density in a watershed, the volume of wastewater entering the lake, as well as the fraction of manure applied in the watershed as fertilizer significantly impacted ARG diversity. Together, these findings indicate that lake resistomes are regularly stocked with resistance genes evolved in the context of both veterinary and human antibiotics use and represent reservoirs of ARGs that require further monitoring.