title: Occurrence of antibiotics and antibiotic resistance genes in hospital and urban wastewaters and their impact on the receiving river.
abstract: Antibiotic resistance has become a major health concern; thus, there is a growing interest in exploring the occurrence of antibiotic resistance genes (ARGs) in the environment as well as the factors that contribute to their emergence. Aquatic ecosystems provide an ideal setting for the acquisition and spread of ARGs due to the continuous pollution by antimicrobial compounds derived from anthropogenic activities. We investigated, therefore, the pollution level of a broad range of antibiotics and ARGs released from hospital and urban wastewaters, their removal through a wastewater treatment plant (WWTP) and their presence in the receiving river. Several antimicrobial compounds were detected in all water samples collected. Among antibiotic families, fluoroquinolones were detected at the highest concentration, especially in hospital effluent samples. Although good removal efficiency by treatment processes was observed for several antimicrobial compounds, most antibiotics were still present in WWTP effluents. The results also revealed that copy numbers of ARGs, such as blaTEM (resistance to β-lactams), qnrS (reduced susceptibility to fluoroquinolones), ermB (resistance to macrolides), sulI (resistance to sulfonamides) and tetW (resistance to tetracyclines), were detected at the highest concentrations in hospital effluent and WWTP influent samples. Although there was a significant reduction in copy numbers of these ARGs in WWTP effluent samples, this reduction was not uniform across analyzed ARGs. Relative concentration of ermB and tetW genes decreased as a result of wastewater treatment, whereas increased in the case of blaTEM, sulI and qnrS genes. The incomplete removal of antibiotics and ARGs in WWTP severely affected the receiving river, where both types of emerging pollutants were found at higher concentration in downstream waters than in samples collected upstream from the discharge point. Taken together, our findings demonstrate a widespread occurrence of antibiotics and ARGs in urban and hospital wastewater and how these effluents, even after treatment, contribute to the spread of these emerging pollutants in the aquatic environment.
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Rodriguez-Mozaz
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Chamorro
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Marti
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
authors.forename: Belinda
authors.initials: B
authors.lastname: Huerta
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Gros
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Sànchez-Melsió
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain; Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, Girona, Spain.
authors.forename: Carles M
authors.initials: CM
authors.lastname: Borrego
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain; Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Spain.
authors.forename: Damià
authors.initials: D
authors.lastname: Barceló
authors.affiliation: Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain. Electronic address: jlbalcazar@icra.cat.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Balcázar
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002947:Cities; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005798:Genes, Bacterial; D005843:Geography; D006761:Hospitals; D045483:Rivers / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D062065:Wastewater
keywords: Antibiotic resistance; Antibiotics; Aquatic ecosystem; Urban and hospital wastewater