title: Tertiary-treated municipal wastewater is a significant point source of antibiotic resistance genes into Duluth-Superior Harbor.
abstract: In this study, the impact of tertiary-treated municipal wastewater on the quantity of several antibiotic resistance determinants in Duluth-Superior Harbor was investigated by collecting surface water and sediment samples from 13 locations in Duluth-Superior Harbor, the St. Louis River, and Lake Superior. Quantitative PCR (qPCR) was used to target three different genes encoding resistance to tetracycline (tet(A), tet(X), and tet(W)), the gene encoding the integrase of class 1 integrons (intI1), and total bacterial abundance (16S rRNA genes) as well as total and human fecal contamination levels (16S rRNA genes specific to the genus  Bacteroides ). The quantities of tet(A), tet(X), tet(W), intI1, total  Bacteroides , and human-specific  Bacteroides  were typically 20-fold higher in the tertiary-treated wastewater than in nearby surface water samples. In contrast, the quantities of these genes in the St. Louis River and Lake Superior were typically below detection. Analysis of sequences of tet(W) gene fragments from four different samples collected throughout the study site supported the conclusion that tertiary-treated municipal wastewater is a point source of resistance genes into Duluth-Superior Harbor. This study demonstrates that the discharge of exceptionally treated municipal wastewater can have a statistically significant effect on the quantities of antibiotic resistance genes in otherwise pristine surface waters.
authors: Department of Civil Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States. lapar001@umn.edu
authors: Timothy M
authors: TM
authors: LaPara
authors: Tucker R
authors: TR
authors: Burch
authors: Patrick J
authors: PJ
authors: McNamara
authors: David T
authors: DT
authors: Tan
authors: Mi
authors: M
authors: Yan
authors: Jessica J
authors: JJ
authors: Eichmiller
mesh_terms: D001439:Bacteroides / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D005618:Fresh Water / Q000382:microbiology*; D005798:Genes, Bacterial; D006801:Humans; D060888:Real-Time Polymerase Chain Reaction; D013753:Tetracycline Resistance; D014865:Waste Disposal, Fluid / Q000379:methods; D018508:Water Purification / Q000379:methods