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Marti E.,Catalan Institute for Water Research | Balcazar J.L.,Catalan Institute for Water Research
Clinical Microbiology and Infection | Year: 2012

A plasmid (pP2G1), which confers multidrug resistance in an environmental Aeromonas species, was completely sequenced using a shotgun approach. Plasmid pP2G1 encoded resistance to aminoglycosides and quinolones [aac(6′)-Ib-cr], β-lactams (blaOXA-1), chloramphenicol (catB3), macrolides [mphA-mrx-mphR], quaternary ammonium compounds (qacEΔ1), quinolones (qnrS2), rifampicin (arr-3) and sulphonamides (sul1). These findings suggest that Aeromonas species may potentially act as reservoirs of antibiotic resistance genes. © 2012 European Society of Clinical Microbiology and Infectious Diseases.


Marti E.,Catalan Institute for Water Research | Balcazar J.L.,Catalan Institute for Water Research
Research in Microbiology | Year: 2014

In this study, we determined the diversity and composition of benthic bacterial communities collected in river sediments upstream and downstream from a wastewater treatment plant (WWTP). Pyrosequencing of bacterial 16S rRNA genes revealed notable differences between the communities from upstream and downstream sites. In particular, a higher relative abundance of Acidobacteria, Chloroflexi, Deltaproteobacteria and Firmicutes and a lower proportion of Gammaproteobacteria and Verrucomicrobia sequences were detected at the downstream site compared to the upstream site. These findings represent a first approximation of the impact of WWTP discharges on environmental microbial communities. © 2014 Institut Pasteur.


Marti E.,Catalan Institute for Water Research | Variatza E.,Catalan Institute for Water Research | Balcazar J.L.,Catalan Institute for Water Research
Clinical Microbiology and Infection | Year: 2014

Six antibiotic resistance genes (blaCTX-M, blaSHV, blaTEM, qnrA, qnrB and qnrS) were quantified by qPCR in both phage and bacterial DNA fractions of environmental water samples in order to determine the contribution of phages to the dissemination of antibiotic resistance genes (ARGs) in the environment. Although the highest copy numbers (p <0.05) of ARGs were detected in the bacterial DNA fraction, qnrS and blaSHV genes were found in the phage DNA from all samples analysed, reaching up to 4 log10 copy numbers/mL in hospital samples. These results indicate that bacteriophages are a potential reservoir of resistance genes and may act as efficient vehicles for horizontal gene transfer. Clinical Microbiology and Infection © 2013 European Society of Clinical Microbiology and Infectious Diseases.


Petrovic M.,Catalan Institute for Water Research | Petrovic M.,Catalan Institution for Research and Advanced Studies
Trends in Environmental Analytical Chemistry | Year: 2014

In the last five years dozens of papers are published on the development, optimization and validation of analytical methodologies for the analysis of pharmaceuticals in aqueous and solid environmental samples, and several hundreds of papers reported on the application of those methods in monitoring studies or studies on the fate and behavior of pharmaceuticals in the environment and during water treatment. In spite of apparent maturity of methods and protocols for the monitoring of pharmaceuticals in the environment, methodological challenges are still numerous. This paper discusses the potential pitfalls in the quantitative multiresidue target analysis of pharmaceuticals in environmental samples, such as preservation of samples, stability of analytes in the sample and in standard solutions, possible losses of analytes due to sorption on the glassware and/or filter materials and matrix effects in MS detection. Recommendations how to avoid or at least minimize the errors and wrong interpretation of data are given. © 2013 Elsevier B.V.


Farre M.,CSIC - Institute of Environmental Assessment And Water Research | Barcelo D.,CSIC - Institute of Environmental Assessment And Water Research | Barcelo D.,Catalan Institute for Water Research
TrAC - Trends in Analytical Chemistry | Year: 2013

Governments all over the world are intensifying their efforts to improve food safety, which are coming in response to an increasing number of food-safety problems and rising consumer concerns. In addition, the variety of toxicant residues in food is increasing continuously as a consequence of industrial development, new agricultural practices, environmental pollution and climate change.This article reviews the new analytical approaches [e.g., coupled chromatography techniques, the use of new extraction materials, multi-dimensional liquid chromatography and novel mass spectrometric methods (e.g., ambient ionization techniques for food analysis)]. We pay special emphasis to reviewing recent literature on analysis of emerging contaminants in food. © 2012.


Gros M.,Catalan Institute for Water Research | Rodriguez-Mozaz S.,Catalan Institute for Water Research | Barcelo D.,Catalan Institute for Water Research | Barcelo D.,CSIC - Institute of Environmental Assessment And Water Research
Journal of Chromatography A | Year: 2012

The present work describes the development of an analytical method, based on automated off-line solid phase extraction (SPE) followed by ultra-high-performance liquid chromatography coupled to quadrupole linear ion trap tandem mass spectrometry (UPLC-QqLIT) for the determination of 81 pharmaceutical residues, covering various therapeutic groups, and some of their main metabolites, in surface and treated waters (influent and effluent wastewaters, river, reservoir, sea and drinking water). For unequivocal identification and confirmation, two selected reaction monitoring (SRM) transitions per compound are monitored. Quantification is performed by the internal standard approach, indispensable to correct matrix effects. Moreover, to obtain an extra tool for confirmation of positive findings, an information dependent acquisition (IDA) experiment was performed, with SRM as survey scan and an enhanced product ion (EPI) scan as dependent scan. Compound identification was carried out by library search, matching the EPI spectra achieved at one fixed collision energy with those present in a library. The main advantages of the method are automation and speed-up of sample preparation by the reduction of extraction volumes for some matrices, the fast separation of a big number of pharmaceuticals, its high sensitivity (limits of detection in the low ng/L range), selectivity, due to the use of tandem mass spectrometry, reliability since a significant number of isotopically labeled compounds are used as internal standards for quantification and finally, the analysis of tap, reservoir and sea waters, since information about occurrence of pharmaceuticals in these matrices is still sparse. As part of the validation procedure, the method developed was applied to the analysis of pharmaceutical residues in waste and surface waters from different sites in Catalonia (North East of Spain). © 2012 Elsevier B.V.


Marti E.,Catalan Institute for Water Research | Jofre J.,University of Barcelona | Balcazar J.L.,Catalan Institute for Water Research
PLoS ONE | Year: 2013

Antibiotic resistance represents a global health problem, requiring better understanding of the ecology of antibiotic resistance genes (ARGs), their selection and their spread in the environment. Antibiotics are constantly released to the environment through wastewater treatment plant (WWTP) effluents. We investigated, therefore, the effect of these discharges on the prevalence of ARGs and bacterial community composition in biofilm and sediment samples of a receiving river. We used culture-independent approaches such as quantitative PCR to determine the prevalence of eleven ARGs and 16S rRNA gene-based pyrosequencing to examine the composition of bacterial communities. Concentration of antibiotics in WWTP influent and effluent were also determined. ARGs such as qnrS, blaTEM, blaCTX-M, blaSHV, erm(B), sul(I), sul(II), tet(O) and tet(W) were detected in all biofilm and sediment samples analyzed. Moreover, we observed a significant increase in the relative abundance of ARGs in biofilm samples collected downstream of the WWTP discharge. We also found significant differences with respect to community structure and composition between upstream and downstream samples. Therefore, our results indicate that WWTP discharges may contribute to the spread of ARGs into the environment and may also impact on the bacterial communities of the receiving river. © 2013 Marti et al.


Marti E.,Catalan Institute for Water Research | Variatza E.,Catalan Institute for Water Research | Balcazar J.L.,Catalan Institute for Water Research
Trends in Microbiology | Year: 2014

Although antibiotic resistance has become a major threat to human health worldwide, this phenomenon has been largely overlooked in studies in environmental settings. Aquatic environments may provide an ideal setting for the acquisition and dissemination of antibiotic resistance, because they are frequently impacted by anthropogenic activities. This review focuses primarily on the emergence and dissemination of antibiotic resistance in the aquatic environment, with a special emphasis on the role of antibiotic resistance genes. © 2013 Elsevier Ltd.


Rodriguez-Caballero A.,Catalan Institute for Water Research | Pijuan M.,Catalan Institute for Water Research
Water Research | Year: 2013

A sequencing batch reactor (SBR) was enriched with ammonia oxidizing bacteria (AOB) in order to treat synthetic reject wastewater (1g NH4 +-N/L). Partial nitrification was successfully achieved at a NH4 +-N to NO2 --N conversion rate of 98%. The emission dynamics of nitrous oxide (N2O) and nitric oxide (NO) were monitored during normal operation and under 3 different cycle configurations. An N2O peak was detected during the first 5min of the cycle in all cases which corresponded to 60-80% of the total N2O emitted. When anoxic phases were introduced, N2O emissions were minimized but NO increased. Factors affecting the initial N2O peak were studied in a set of individual experiments. It was concluded that most of this N2O originated during settling due to biological reactions. Complete oxidation of NH4 + (or most likely hydroxylamine) as a result of sufficient aeration time can be a minimization strategy for N2O emissions in partial nitrification systems. © 2013 Elsevier Ltd.


Marti E.,Catalan Institute for Water Research | Balcazar J.L.,Catalan Institute for Water Research
Applied and Environmental Microbiology | Year: 2013

Real-time PCR assays were developed for the enumeration of plasmid-mediated quinolone resistance (PMQR) determinants,such as the qnrA, qnrB, and qnrS genes, in different water samples and chicken feces. The results indicate that the developedassays are specific and sensitive for the quantification of qnr genes in complex samples. © 2013, American Society for Microbiology.

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