| 1. |
- Bengtsson-Palme, Johan, 1985, et al.
(författare)
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Elucidating selection processes for antibiotic resistance in sewage treatment plants using metagenomics
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 572, s. 697-712
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Tidskriftsartikel (refereegranskat)abstract
- Sewage treatment plants (STPs) have repeatedly been suggested as “hotspots” for the emergence and dissemination of antibiotic-resistant bacteria. A critical question still unanswered is if selection pressures within STPs, caused by residual antibiotics or other co-selective agents, are sufficient to specifically promote resistance. To address this, we employed shotgun metagenomic sequencing of samples from different steps of the treatment process in three Swedish STPs. In parallel, concentrations of selected antibiotics, biocides and metals were analyzed. We found that concentrations of tetracycline and ciprofloxacin in the influent were above predicted concentrations for resistance selection, however, there was no consistent enrichment of resistance genes to any particular class of antibiotics in the STPs, neither for biocide and metal resistance genes. The most substantial change of the bacterial communities compared to human feces occurred already in the sewage pipes, manifested by a strong shift from obligate to facultative anaerobes. Through the treatment process, resistance genes against antibiotics, biocides and metals were not reduced to the same extent as fecal bacteria. The OXA-48 gene was consistently enriched in surplus and digested sludge. We find this worrying as OXA-48, still rare in Swedish clinical isolates, provides resistance to carbapenems, one of our most critically important classes of antibiotics. Taken together, metagenomics analyses did not provide clear support for specific antibiotic resistance selection. However, stronger selective forces affecting gross taxonomic composition, and with that resistance gene abundances, limit interpretability. Comprehensive analyses of resistant/non-resistant strains within relevant species are therefore warranted.
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| 2. |
- Flach, Carl-Fredrik, 1977, et al.
(författare)
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Does antifouling paint select for antibiotic resistance?
- 2017
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 590, s. 461-468
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Tidskriftsartikel (refereegranskat)abstract
- There is concern that heavy metals and biocides contribute to the development of antibiotic resistance via co-selection. Most antifouling paints contain high amounts of such substances, which risks turning painted ship hulls into highly mobile refuges and breeding grounds for antibiotic-resistant bacteria. The objectives of this study were to start investigate if heavy-metal based antifouling paints can pose a risk for co-selection of antibiotic-resistant bacteria and, if so, identify the underlying genetic basis. Plastic panels with one side painted with copper and zinc-containing antifouling paint were submerged in a Swedish marina and biofilms from both sides of the panels were harvested after 2.5-4 weeks. DNA was isolated from the biofilms and subjected to metagenomic sequencing. Biofilm bacteria were cultured on marine agar supplemented with tetracycline, gentamicin, copper sulfate or zinc sulfate. Biofilm communities from painted surfaces displayed lower taxonomic diversity and enrichment of Gammaproteobacteria. Bacteria from these communities showed increased resistance to both heavy metals and tetracycline but not to gentamicin. Significantly higher abundance of metal and biocide resistance genes was observed, whereas mobile antibiotic resistance genes were not enriched in these communities. In contrast, we found an enrichment of chromosomal RND efflux system genes, including such with documented ability to confer decreased susceptibility to both antibiotics and biocides/heavy metals. This was paralleled by increased abundances of integron-associated integrase and ISCR transposase genes. The results show that the heavy metal-based antifouling paint exerts a strong selection pressure on marine bacterial communities and can co-select for certain antibiotic-resistant bacteria, likely by favoring species and strains carrying genes that provide cross-resistance. Although this does not indicate an immediate risk for promotion of mobile antibiotic resistance, the clear increase of genes involved in mobilizing DNA provides a foundation for increased opportunities for gene transfer in such communities, which might also involve yet unknown resistance mechanisms.
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| 3. |
- Grabicova, K, et al.
(författare)
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Tissue-specific bioconcentration of antidepressants in fish exposed to effluent from a municipal sewage treatment plant
- 2014
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 488-489, s. 46-50
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Tidskriftsartikel (refereegranskat)abstract
- Tissue-specific bioconcentration of selected antidepressants was studied in rainbow trout (Oncorhynchus mykiss) exposed to undiluted effluent from a Swedish municipal sewage treatment plant for 13 days. Citalopram, sertraline and venlafaxine were found in the brains and livers of most fish, but not in blood plasma or muscle. Venlafaxine was the only drug found in plasma (3/20 fish). Fluoxetine was not detected in any fish tissue, in accordance with a low concentration in the effluent and a comparably high limit of quantification in tissues. Concentrations of citalopram, sertraline and venlafaxine in fish brain were up to 1/12, 1/8 and 1/26, respectively, of the lowest concentrations found in the brains of mammals treated with therapeutic doses. Thus, given co-exposure to several antidepressants and an assumed similar potency in fish, the margin of safety for target-related effects in fish residing in effluent-dominated streams is relatively low. Furthermore, the non-detectable levels of these drugs in blood plasma suggest that analyses of concentrations in target tissues (brain) would be more informative in field studies and other studies with environmentally realistic exposure concentrations.
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| 4. |
- Lundström, Sara, 1981, et al.
(författare)
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Minimal selective concentrations of tetracycline in complex aquatic bacterial biofilms
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 553, s. 587-95
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Tidskriftsartikel (refereegranskat)abstract
- Selection pressure generated by antibiotics released into the environment could enrich for antibiotic resistance genes and antibiotic resistant bacteria, thereby increasing the risk for transmission to humans and animals. Tetracyclines comprise an antibiotic class of great importance to both human and animal health. Accordingly, residues of tetracycline are commonly detected in aquatic environments. To assess if tetracycline pollution in aquatic environments promotes development of resistance, we determined minimal selective concentrations (MSCs) in biofilms of complex aquatic bacterial communities using both phenotypic and genotypic assays. Tetracycline significantly increased the relative abundance of resistant bacteria at 10 μg/L, while specific tet genes (tetA and tetG) increased significantly at the lowest concentration tested (1 μg/L). Taxonomic composition of the biofilm communities was altered with increasing tetracycline concentrations. Metagenomic analysis revealed a concurrent increase of several tet genes and a range of other genes providing resistance to different classes of antibiotics (e.g. cmlA, floR, sul1, and mphA), indicating potential for co-selection. Consequently, MSCs for the tet genes of ≤ 1 μg/L suggests that current exposure levels in e.g. sewage treatment plants could be sufficient to promote resistance. The methodology used here to assess MSCs could be applied in risk assessment of other antibiotics as well.
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| 5. |
- Mustafa, Majid, et al.
(författare)
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Regeneration of saturated activated carbon by electro-peroxone and ozonation: Fate of micropollutants and their transformation products
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 776
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Tidskriftsartikel (refereegranskat)abstract
- Many micropollutants (MPs) that may adversely affect aquatic life when released into the environment are common in modern societies. The presence of MPs in the environment is frequently connected to release from wastewater treatment plants. Therefore, advanced treatments are needed to remove these MPs. Powdered activated carbon (PAC) efficiently removes MPs in both laboratory experiments and full-scale applications. However, its single-use nature and the difficulty of handling spent PAC have limited the popularity of this approach. Therefore, various methods for PAC regeneration have been investigated. The current study compares two methods for regenerating spent PAC saturated with MPs: ozonation and the electro-peroxone (E-peroxone) process. Six MPs were tested: benzotriazole, carbamazepine, ciprofloxacin, diclofenac, perfluorooctanoic acid (PFOA), and trimethoprim. Both methods achieved regeneration efficiencies (REs) of >100% for four of the MPs. However, the REs for diclofenac (95–102%) and PFOA (67–69%) were below 100%. Surface characterization showed that PAC regeneration did not restore the micro- and mesopores that are mainly responsible for MPs sorption by virgin PAC. Instead, MPs sorption onto regenerated PAC was determined to be related to different interactions between PAC surface and MPs' ionic states including electrostatic, H-bonding, and electron donor-acceptor interactions. Transformation products of adsorbed MPs typically remained sorbed on the regenerated PAC rather than being transferred to the regeneration effluent.
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| 6. |
- Östman, Marcus, 1987-, et al.
(författare)
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A snapshot of illicit drug use in Sweden acquired through sewage water analysis
- 2014
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 472, s. 862-871
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Tidskriftsartikel (refereegranskat)abstract
- Analytical measurements of sewage water have been used many times to estimate the consumption of specific drugs in an area. This study measured a large number of illicit drugs and metabolites (>30) at a large number of sewage treatment plants (STPs) distributed across Sweden. Twenty-four illicit and prescription drugs, classified as narcotic substances in Sweden, and seven selected metabolites were included in the study. A 24 hour composite sample of incoming sewage water was collected from 33 different municipalities at various geographic locations across Sweden. Species were analyzed using an on-line solid-phase extraction-liquid chromatography electrospray tandem mass spectrometry method. The method proved to be rapid with minimum need for sample work up and was able to detect 13 compounds above their respective limits of quantification. The results for all compounds were presented as per capita loads. Multivariate data analysis was used to relate drug consumption to geographical location and/or population of cities. The results showed that geographical differences in drug consumption were apparent across the country. For the narcotic pharmaceuticals, the geographical differences suggested by the multivariate model were supported by prescription statistics. (C) 2013 Elsevier B.V. All rights reserved.
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| 7. |
- Östman, Marcus, et al.
(författare)
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Detailed mass flows and removal efficiencies for biocides and antibiotics in Swedish sewage treatment plants
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 640, s. 327-336
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial compounds, such as biocides and antibiotics, are widely used in society with significant quantities of these chemicals ending up in sewage treatment plants (STPs). In this study, mass flows and removal efficiency in different treatment steps at three Swedish STPs were evaluated for eleven different biocides and antibiotics. Mass flows were calculated at eight different locations (incoming wastewater, water after the first sedimentation step, treated effluent, primary sludge, surplus sludge, digested sludge, dewatered digested sludge and reject water). Samples were collected for a total of nine days over three weeks. The STPs were able to remove 53-> 99% of the antimicrobial compounds and 0-64% were biodegraded on average in the three STPs. Quaternary ammonium compounds were removed from the wastewater N99%, partly through biodegradation, but 38-96% remained in the digested sludge. Chlorhexidine was not biodegraded but was efficiently removed from the wastewater to the sludge. The biological treatment step was the most important step for the degradation of the studied compounds, but also removed several compounds through the surplus sludge. Compounds that were inefficiently removed included benzotriazoles, trimethoprim and fluconazole. The study provides mass flows and removal efficiencies for several compounds that have been seldom studied.
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| 8. |
- Östman, Marcus, et al.
(författare)
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Effect of full-scale ozonation and pilot-scale granular activated carbon on the removal of biocides, antimycotics and antibiotics in a sewage treatment plant
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 649, s. 1117-1123
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Tidskriftsartikel (refereegranskat)abstract
- Several micropollutants show low removal efficiencies in conventional sewage treatment plants, and therefore enter the aquatic environment. To reduce the levels of micropollutants in sewage effluent, and thereby the effects on biota, a number of extra treatment steps are currently being evaluated. Two such techniques are ozonation and adsorption onto activated carbon. In this study, we investigated the efficiency of Sweden's first full-scale ozonation treatment plant at removing a number of antibiotics, antimycotics and biocides. The effect of adding granular activated carbon (GAC) on a pilot scale and pilot-scale ozonation were also evaluated. The conventional treatment (13,000 PE) with the add-on of full-scale ozonation (0.55 g O-3/g Total organic carbon (TOC)) was able to remove most of the studied compounds (>90%), except for benzotriazoles and fluconazole (<50%). Adsorption on GAC on a pilot scale showed a higher removal efficiency than ozonation (>80% for all studied compounds). Three types of GAC were evaluated and shown to have different removal efficiencies. In particular, the GAC with the smallest particle sizes exhibited the highest removal efficiency. The results demonstrate that it is important to select an appropriate type of carbon to achieve the removal goal for specific target compounds.
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