title: Impact of wastewater treatment processes on antimicrobial resistance genes and their co-occurrence with virulence genes in Escherichia coli.
abstract: An increase in the frequency of antimicrobial resistance genes (ARGs) in bacteria including Escherichia coli could be a threat to public health. This study investigated the impact of activated sludge and physicochemical wastewater treatment processes on the prevalence of ARGs in E. coli isolates. In total, 719 E. coli were isolated from the influent and effluent (prior to disinfection) of two activated sludge and two physicochemical municipal treatment plants, and genotyped using DNA microarrays. Changes in the abundance of ARGs in the E. coli population were different for the two treatment processes. Activated sludge treatment did not change the prevalence of ARG-possessing E. coli but increased the abundance of ARGs in the E. coli genome while physicochemical treatment reduced both the prevalence of ARG-carrying E. coli as well as the frequency of ARGs in the E. coli genome. Most E. coli isolates from the four treatment plants possessed ARGs of multiple antimicrobial classes, mainly aminoglycoside, β-lactams, quinolone and tetracyclines. In addition these isolates harboured DNA insertion sequence elements including integrase and transposase. A significant positive association was found between the occurrence of ARGs and virulence genotypes.
authors.affiliation: Department of Civil Engineering and Applied Mechanics, McGill University, Montréal, Québec H3A 0C3, Canada.
authors.forename: Basanta Kumar
authors.initials: BK
authors.lastname: Biswal
authors.affiliation: National Research Council of Canada, Montréal, Québec H4P 2R2, Canada.
authors.forename: Alberto
authors.initials: A
authors.lastname: Mazza
authors.affiliation: National Research Council of Canada, Montréal, Québec H4P 2R2, Canada.
authors.forename: Luke
authors.initials: L
authors.lastname: Masson
authors.affiliation: Department of Civil Engineering and Applied Mechanics, McGill University, Montréal, Québec H3A 0C3, Canada.
authors.forename: Ronald
authors.initials: R
authors.lastname: Gehr
authors.affiliation: Department of Civil Engineering and Applied Mechanics, McGill University, Montréal, Québec H3A 0C3, Canada. Electronic address: dominic.frigon@mcgill.ca.
authors.forename: Dominic
authors.initials: D
authors.lastname: Frigon
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016000:Cluster Analysis; D004251:DNA Transposable Elements / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000187:drug effects / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D005798:Genes, Bacterial / Q000235:genetics*; D005838:Genotype; D032023:Integrons / Q000235:genetics; D010802:Phylogeny; D014774:Virulence / Q000187:drug effects / Q000235:genetics*; D062065:Wastewater / Q000382:microbiology*; D018508:Water Purification / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D062065:Wastewater
keywords: Activated sludge; Antimicrobial resistance genes; DNA microarray; Escherichia coli; Insertion sequence elements; Physicochemical