Effects of industrial effluents containing moderate levels of antibiotic mixtures on the abundance of antibiotic resistance genes and bacterial community composition in exposed creek sediments

Milaković, Milena; Vestergaard, Gisle; González-Plaza, Juan José; Petrić, Ines; Kosić-Vukšić, Josipa; Senta, Ivan; Kublik, Susanne; Schloter, Michael; Udiković-Kolić, Nikolina (2020) Effects of industrial effluents containing moderate levels of antibiotic mixtures on the abundance of antibiotic resistance genes and bacterial community composition in exposed creek sediments. Science of the Total Environment, 706 . ISSN 0048-9697

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Abstract

Environmental discharges of very high (mg/L) antibiotic levels from pharmaceutical production contributed to the selection, spread and persistence of antibiotic resistance. However, the effects of less antibiotic-polluted effluents (μg/L) from drug-formulation on exposed aquatic microbial communities are still scarce. Here we analyzed formulation effluents and sediments from the receiving creek collected at the discharge site (DW0), upstream (UP) and 3000 m downstream of discharge (DW3000) during winter and summer season. Chemical analyses indicated the largest amounts of trimethoprim (up to 5.08 mg/kg) and azithromycin (up to 0.39 mg/kg) at DW0, but sulfonamides accumulated at DW3000 (total up to 1.17 mg/kg). Quantitative PCR revealed significantly increased relative abundance of various antibiotic resistance genes (ARGs) against β-lactams, macrolides, sulfonamides, trimethoprim and tetracyclines in sediments from DW0, despite relatively high background levels of some ARGs already at UP site. However, only sulfonamide (sul2) and macrolide ARG subtypes (mphG and msrE) were still elevated at DW3000 compared to UP. Sequencing of 16S rRNA genes revealed pronounced changes in the sediment bacterial community composition from both DW sites compared to UP site, regardless of the season. Numerous taxa with increased relative abundance at DW0 decreased to background levels at DW3000, suggesting die-off or lack of transport of effluent-originating bacteria. In contrast, various taxa that were more abundant in sediments than in effluents increased in relative abundance at DW3000 but not at DW0, possibly due to selection imposed by high sulfonamide levels. Network analysis revealed strong correlation between some clinically relevant ARGs (e.g. blaGES, blaOXA, ermB, tet39, sul2) and taxa with elevated abundance at DW sites, and known to harbour opportunistic pathogens, such as Acinetobacter, Arcobacter, Aeromonas and Shewanella. Our results demonstrate the necessity for improved management of pharmaceutical and rural waste disposal for mitigating the increasing problems with antibiotic resistance.

Item Type:	Article
Additional Information:	This work has been supported by the Croatian Science Foundation under the project number UIP-2014-09-9350. Dr. Gisle Vestergaard was supported by a Humboldt Research Fellowship for postdoctoral researchers. We thank Dr. Ana Bielen and Dr. Ana Simatovi for assistance in sample collection and processing and to Nenad Muhin for the technical assistance.
Uncontrolled Keywords:	antibiotic manufacturing; sediment; pollution; bacterial community; antibiotic resistance genes
Subjects:	NATURAL SCIENCES > Interdisciplinary Natural Sciences NATURAL SCIENCES > Interdisciplinary Natural Sciences > Environmental Science
Divisions:	Division for Marine and Enviromental Research
Projects:	Project title Project leader Project code Project type Istraživanje utjecaja otpadnih voda iz farmaceutskih industrija na sastav i profil antibiotičke rezistencije izloženih mirkobnih zajednica u slatkovodnim sedimentima-WINAR Nikolina Udiković Kolić UIP-2014-09-9350 HRZZ
Depositing User:	Milena Milaković Obradović
Date Deposited:	29 Apr 2020 12:07
URI:	http://fulir.irb.hr/id/eprint/5461
DOI:	10.1016/j.scitotenv.2019.136001

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