A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants

The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum β-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (<0.1% to 38.3%), being positively correlated (p < 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 103 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status

A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants

The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum β-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (<0.1% to 38.3%), being positively correlated (p < 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 10 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status. [Abstract copyright: Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.

Tackling antibiotic resistance: the environmental framework

Antibiotic resistance is a threat to human and animal health worldwide, and key measures are required to reduce the risks posed by antibiotic resistance genes that occur in the environment. These measures include the identification of critical points of control, the development of reliable surveillance and risk assessment procedures, and the implementation of technological solutions that can prevent environmental contamination with antibiotic resistant bacteria and genes. In this Opinion article, we discuss the main knowledge gaps, the future research needs and the policy and management options that should be prioritized to tackle antibiotic resistance in the environment

Response of the PCB-contaminated soil bacterial community to applied bioremediation treatments

International audienc

ECOFUN-MICROBIODIV: an FP7 European project to estimate the ecotoxicological impact of low dose pesticide application in agriculture on soil functional microbial diversity

International audienceSoil is hosting a tremendous microbial diversity playing a key-role in a number of soil ecosystemic services including nutrient cycling and filtering. ln the European Soil Framework Directive pesticides are clearly marked as one of the major threats for soil biodiversity and functioning. ln orcier to guarantee minimum effects of pesticide application on soil microbes, pesticicleregistration at EU level (Regulation 2006/388) consiclers the toxicity of pesticides ontci non targefsoil microbes by relying on carbon- and nitrcigen-mineralization tests (OECO 216, 217). However tnese tests do not provicle a comprehensive assessment of pesticides onto soil microbes.-ECOFUN-MICROBIODIV was a project cleclicated to cleveloping and evaluating innovativetools toestimate the ecotoxicological impact of sulphonylurea herbicide nicosulfuron on sail micrcibial diversity and functioning. ln orcier to gain full insights into the potential toxiCify of the targeted herbicide a research consortium was established comprised of teams with expertise in agronomy, soif and environmental chemistry, environmental microbiology, soif molecular biology and biochemistry. Two scenario of exposure were considered (i) Tier 1, the worst case scenario, consisting in an experiment conclucted in a greenhouse with up to xl000 of the nicosulfuron dose applied and (ii) Tier Il, the agronomical scenario, consisting in an experiment conducted in the field (1 x, 2x and Sx of nicosulfuron) Agronomical parameters were recorded for bath experiments (yield of crop, weeds development, root and shoot biomass of corn). Sail and corn root sampling was carried out ali along the experiment. The fate of nicosulfuron was monitored in soil by HPLC-UV.The impact of herbicide was estimated using standard methods aimed at studying the abundance (IS014240:2), diversity (ISO/TS29843-1), and the activity (TS29843-1) of the soil microflora. ln addition, new methods based on direct soil DNA extraction (ISO 11 063) were appliecl to determine herbicide impact on structure and abundance of fungal and bacterial communities, structure, abundance, and activity of the functional communities involved in C and N cycling and on the formation of endomycorhizal ; symbiosis. Results suggested that for the good understanding of the impact of low-dose herbicide, such as nicosulfuron, on the abundance, structure, diversity, and activity of sail microbial community it is necessary to use tools of different resolution levels. Application of such multidisciplinary approach relying on biochemistry and molecular biology gives a good tl estimation of the pesticide impact. Results suggested thalif the impact of law-close pesticide wouId beonlyconsidered using the dominant microbial populations it could be underestimated. The consideration of liner approaches allowing to target specifically a functional community or togo deeper in the phylogeny was proven to give a more accurate estimation of the impact of low dose pesticide onto sail microflora

Processes involved in the adaptation of soil microbiota to enhance biodegradation of pesticides: atrazine-degrading community as a study case

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Taxonomic and functional diversity of atrazine-degrading bacterial communities enriched from agrochemical factory soil

International audienceAims: To characterize atrazine-degrading potential of bacterial communities enriched from agrochemical factory soil by analysing diversity and organization of catabolic genes. Methods and Results: The bacterial communities enriched from three different sites of varying atrazine contamination mineralized 65–80% of 14C ring-labelled atrazine. The presence of trzN-atzBC-trzD, trzN-atzABC-trzD and trzN-atzABCDEF-trzD gene combinations was determined by PCR. In all enriched communities, trzN-atzBC genes were located on a 165-kb plasmid, while atzBC or atzC genes were located on separated plasmids. Quantitative PCR revealed that catabolic genes were present in up to 4% of the community. Restriction analysis of 16S rDNA clone libraries of the three enrichments revealed marked differences in microbial community structure and diversity. Sequencing of selected clones identified members belonging to Proteobacteria (α-, β- and γ-subclasses), the Actinobacteria, Bacteroidetes and TM7 division. Several 16S rRNA gene sequences were closely related to atrazine-degrading community members previously isolated from the same contaminated site. Conclusions: The enriched communities represent a complex and diverse bacterial associations displaying heterogeneity of catabolic genes and their functional redundancies at the first steps of the upper and lower atrazine-catabolic pathway. The presence of catabolic genes in small proportion suggests that only a subset of the community has the capacity to catabolize atrazine. Significance and Impact of the Study: This study provides insights into the genetic specificity and the repertoire of catabolic genes within bacterial communities originating from soils exposed to long-term contamination by s-triazine compounds

Nicosulfuron application in agricultural soils drives the selection towards NS-tolerant microorganisms harboring various levels of sensitivity to nicosulfuron

The action mode of sulfonylurea herbicides is the inhibition of the acetohydroxyacid synthase (AHAS) required for the biosynthesis of amino acids valine and isoleucine in plants. However, this enzyme is also present in a range of non-targeted organisms, among which soil microorganisms are known for their pivotal role in ecosystem functioning. In order to assess microbial toxicity of sulfonylurea herbicide nicosulfuron (NS), a tiered microcosm (Tier I) to field (Tier II) experiment was designed. Soil bacteria harboring AHAS enzyme tolerant to the herbicide nicosulfuron were enumerated, isolated, taxonomically identified, and physiologically characterized. Results suggested that application of nicosulfuron drives the selection towards NS-tolerant bacteria, with increasing levels of exposure inducing an increase in their abundance and diversity in soil. Tolerance to nicosulfuron was shown to be widespread among the microbial community with various bacteria belonging to Firmicutes (Bacillus) and Actinobacteria (Arthrobacter) phyla representing most abundant and diverse clusters. While Arthrobacter bacterial population dominated community evolved under lower (Tier II) nicosulfuron selection pressure, it turns out that Bacillus dominated community evolved under higher (Tier I) nicosulfuron selection pressure. Different NS-tolerant bacteria likewise showed different levels of sensitivity to the nicosulfuron estimated by growth kinetics on nicosulfuron. As evident, Tier I exposure allowed selection of populations able to better cope with nicosulfuron. One could propose that sulfonylureas-tolerant bacterial community could constitute a useful bioindicator of exposure to these herbicides for assessing their ecotoxicity towards soil microorganisms. © 2015, Springer-Verlag Berlin Heidelberg