Optimizing the final rest period of sludge treatment wetlands: Assessment of biosolids quality.

Wastewater Treatment Plants (WWTPs) generate a substantial amount of sludge as a residue of the wastewater treatment process. The management of this sludge requires the adoption of cost-effective and environmentally friendly techniques. Sludge Treatment Wetlands (STW) have emerged as an effective means to manage and treat sludge, resulting in the production of biosolids suitable for agricultural purposes.

Biotransformation pathways of pharmaceuticals and personal care products (PPCPs) during acidogenesis and methanogenesis of anaerobic digestion.

Pharmaceuticals and personal care products (PPCPs) exhibit varying biodegradability during the acidogenic and methanogenic phases of anaerobic digestion. However, there is limited information regarding the end products generated during these processes. This work investigates the biotransformation products (BTPs) generated in a two-phase (TP) acidogenic-methanogenic (Ac-Mt) bioreactor using advanced suspect and nontarget strategies.

Modeling Antibiotic Concentrations in the Vicinity of Antibiotic-Producing Bacteria at the Micron Scale.

It is generally thought that antibiotics confer upon the producing bacteria the ability to inhibit or kill neighboring microorganisms, thereby providing the producer with a significant competitive advantage. Were this to be the case, the concentrations of emitted antibiotics in the vicinity of producing bacteria might be expected to fall within the ranges of MICs that are documented for a number of bacteria. Furthermore, antibiotic concentrations that bacteria are punctually or chronically exposed to in environments harboring antibiotic-producing bacteria might fall within the range of minimum selective concentrations (MSCs) that confer a fitness advantage to bacteria carrying acquired antibiotic resistance genes.

Does Environmental Exposure to Pharmaceutical and Personal Care Product Residues Result in the Selection of Antimicrobial-Resistant Microorganisms, and is this Important in Terms of Human Health Outcomes?

The environment plays a critical role in the development, dissemination, and transmission of antimicrobial resistance (AMR). Pharmaceuticals and personal care products (PPCPs) enter the environment through direct application to the environment and through anthropogenic pollution. Although there is a growing body of evidence defining minimal selective concentrations (MSCs) of antibiotics and the role antibiotics play in horizontal gene transfer (HGT), there is limited evidence on the role of non-antibiotic PPCPs.

Fate of Clostridia and other spore-forming Firmicute bacteria during feedstock anaerobic digestion and aerobic composting.

Pathogenic spore-forming Firmicutes are commonly present in animal and human wastes that are used as fertilizers in crop production. Pre-treatments of organic waste prior to land application offer the potential to abate enteric microorganisms, and therefore reduce the risk of contamination of crops or adjacent water resources with pathogens carried in these materials. The inactivation and reduction of gram-positive spore formers such as Clostridium spp.

Global dispersal and potential sources of antibiotic resistance genes in atmospheric remote depositions.

Antibiotic resistance has become a major Global Health concern and a better understanding on the global spread mechanisms of antibiotic resistant bacteria (ARB) and intercontinental ARB exchange is needed. We measured atmospheric depositions of antibiotic resistance genes (ARGs) by quantitative (q)PCR in rain/snow collected fortnightly along 4 y. at a remote high mountain LTER (Long-Term Ecological Research) site located above the atmospheric boundary layer (free troposphere).

Impact of chicken litter pre-application treatment on the abundance, field persistence, and transfer of antibiotic resistant bacteria and antibiotic resistance genes to vegetables.

Treatment of manures prior to land application can potentially reduce the abundance of antibiotic resistance genes and thus the risk of contaminating crops or water resources. In this study, raw and composted chicken litter were applied to field plots that were cropped to carrots, lettuce and radishes. Vegetables were washed per normal culinary practice before downstream analysis.

Composting of chicken litter from commercial broiler farms reduces the abundance of viable enteric bacteria, Firmicutes, and selected antibiotic resistance genes.

We examined the ability of composting to remove ARGs and enteric bacteria in litter obtained from broiler chickens fed with a diet supplemented with Bacitracin methylene disalicylate (BDM) (conventional chicken litter), or an antibiotic-free diet (raised without antibiotic (RWA) chicken litter). This was done by evaluating the litter before and after composting for the abundance of ten gene targets associated with antibiotic resistance or horizontal gene transfer, the composition of the bacterial communities, and the abundance of viable enteric bacteria. The abundance of gene targets was determined by qPCR and the microbial community composition of chicken litter determined by 16S rRNA gene amplicon sequencing.

High-quality treated wastewater causes remarkable changes in natural microbial communities and intI1 gene abundance.

We carry out a mesocosms experiment to assess the impact of high-quality treated wastewater intended for agricultural reuse (HQWR) on freshwater bacteria seldom exposed to anthropogenic pollution. Effects were assessed by comparing the abundance and composition of bacterial communities as well as their resistance profile under control (source water from an unpolluted lake) and treatment conditions (source water mixed 1:1 with HQWR, with and without 5 μg L of cefotaxime). We investigated the effect of the different conditions on the abundance of genes encoding resistance to β-lactams and carbapenems (bla, bla, bla and bla), fluoroquinolones (qnrS), tetracyclines (tetA), sulfonamides (sul2), macrolides (ermB), arsenic and cadmium (arsB and czcA, respectively), and on the gene encoding the Class 1 integron integrase (intI1).

Does Dietary Consumption of Antibiotics by Humans Promote Antibiotic Resistance in the Gut Microbiome?

Mandated authorities have developed principles for evaluating the safety of antimicrobial residues in food and have established microbiological acceptable daily intakes (ADIs) and recommended maximum residue limits (MRLs) for antibiotic residues in food products. The evaluation of the ADI is based in relevant scientific information such as MIC data of predominant human intestinal bacteria. However, it does not include data derived from minimal selective concentration (MSC) predictions that estimate the lowest concentration of an antibiotic that will provide resistant bacteria an advantage over susceptible bacteria.

Antibiotic resistance in urban and hospital wastewaters and their impact on a receiving freshwater ecosystem.

The main objective of this study was to investigate the antibiotic resistance (AR) levels in wastewater (WW) and the impact on the receiving river. Samples were collected once per season over one year in the WW of a hospital, in the raw and treated WW of two wastewater treatment plants (WWTPs), as well as upstream and downstream from the release of WWTPs effluents into the Zenne River (Belgium). Culture-dependent methods were used to quantify Escherichia coli and heterotrophic bacteria resistant to amoxicillin, sulfamethoxazole, nalidixic acid and tetracycline.

Emerging contaminants and nutrients synergistically affect the spread of class 1 integron-integrase (intI1) and sul1 genes within stable streambed bacterial communities.

Wastewater effluents increase the nutrient load of receiving streams while introducing a myriad of anthropogenic chemical pollutants that challenge the resident aquatic (micro)biota. Disentangling the effects of both kind of stressors and their potential interaction on the dissemination of antibiotic resistance genes in bacterial communities requires highly controlled manipulative experiments. In this work, we investigated the effects of a combined regime of nutrients (at low, medium and high concentrations) and a mixture of emerging contaminants (ciprofloxacin, erythromycin, sulfamethoxazole, diclofenac, and methylparaben) on the bacterial composition, abundance and antibiotic resistance profile of biofilms grown in artificial streams.

Antibiotic resistance along an urban river impacted by treated wastewaters.

Urban rivers are impacted ecosystems which may play an important role as reservoirs for antibiotic-resistant (AR) bacteria. The main objective of this study was to describe the prevalence of antibiotic resistance along a sewage-polluted urban river. Seven sites along the Zenne River (Belgium) were selected to study the prevalence of AR Escherichia coli and freshwater bacteria over a 1-year period.

Wastewater pollution differently affects the antibiotic resistance gene pool and biofilm bacterial communities across streambed compartments.

Wastewater discharges introduce antibiotic residues and antibiotic-resistant bacteria (ARB) into surface waters. Both inputs directly affect the streambed resistome, either by exerting a selective pressure that favour the proliferation of resistant phenotypes or by enriching the resident communities with wastewater-associated ARB. Here, we investigated the impact of raw and treated urban wastewater discharges on epilithic (growing on rocks) and epipsammic (growing on sandy substrata) streambed biofilms.

Abundance of carbapenemase genes (bla, bla and bla) in wastewater effluents from Tunisian hospitals.

Carbapenems are β-lactam antibiotics with a broad spectrum of activity and are usually considered the last resort for the treatment of severe infections caused by multidrug-resistant pathogens. The clinically most significant carbapenemases are KPC, NDM, and OXA-48-like enzymes, whose genes have been increasingly reported worldwide in members of the family Enterobacteriaceae. In this study, we quantified the abundance of these genes in wastewater effluents from different Tunisian hospitals.

Abundance and Co-Distribution of Widespread Marine Archaeal Lineages in Surface Sediments of Freshwater Water Bodies across the Iberian Peninsula.

Archaea inhabiting marine and freshwater sediments have a relevant role in organic carbon mineralization, affecting carbon fluxes at a global scale. Despite current evidences suggesting that freshwater sediments largely contribute to this process, few large-scale surveys have been addressed to uncover archaeal diversity and abundance in freshwater sedimentary habitats. In this work, we quantified and high-throughput sequenced the archaeal 16S rRNA gene from surficial sediments collected in 21 inland waterbodies across the Iberian Peninsula differing in typology and trophic status.

Real-time PCR assays for the detection and quantification of carbapenemase genes (bla , bla , and bla ) in environmental samples.

In this study, we have developed real-time PCR assays using SYBR Green chemistry to detect all known alleles of bla , bla , and bla -like carbapenemase genes in water, sediment, and biofilm samples collected from hospital and wastewater treatment plant (WWTP) effluents and rivers receiving chronic WWTP discharges. The amplification of bla , bla , and bla DNA was linear over 7 log dilutions (R between 0.995 and 0.

Exploring the contribution of bacteriophages to antibiotic resistance.

Bacteriophages (phages) are the most abundant and diverse biological entities in our planet. They infect susceptible bacterial hosts into which they either multiply or persist. In the latter case, phages can confer new functions to their hosts as a result of gene transfer, thus contributing to their adaptation (short-term) and evolution (long-term).

Metagenomic analysis reveals that bacteriophages are reservoirs of antibiotic resistance genes.

A metagenomics approach was applied to explore the presence of antibiotic resistance genes (ARGs) in bacteriophages from hospital wastewater. Metagenomic analysis showed that most phage sequences affiliated to the order Caudovirales, comprising the tailed phage families Podoviridae, Siphoviridae and Myoviridae. Moreover, the relative abundance of ARGs in the phage DNA fraction (0.

The role of biofilms as environmental reservoirs of antibiotic resistance.

Antibiotic resistance has become a significant and growing threat to public and environmental health. To face this problem both at local and global scales, a better understanding of the sources and mechanisms that contribute to the emergence and spread of antibiotic resistance is required. Recent studies demonstrate that aquatic ecosystems are reservoirs of resistant bacteria and antibiotic resistance genes as well as potential conduits for their transmission to human pathogens.