| 1. |
- Locke, Adam E, et al.
(author)
-
Genetic studies of body mass index yield new insights for obesity biology.
- 2015
-
In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 518:7538, s. 197-401
-
Journal article (peer-reviewed)abstract
- Obesity is heritable and predisposes to many diseases. To understand the genetic basis of obesity better, here we conduct a genome-wide association study and Metabochip meta-analysis of body mass index (BMI), a measure commonly used to define obesity and assess adiposity, in up to 339,224 individuals. This analysis identifies 97 BMI-associated loci (P < 5 × 10(-8)), 56 of which are novel. Five loci demonstrate clear evidence of several independent association signals, and many loci have significant effects on other metabolic phenotypes. The 97 loci account for ∼2.7% of BMI variation, and genome-wide estimates suggest that common variation accounts for >20% of BMI variation. Pathway analyses provide strong support for a role of the central nervous system in obesity susceptibility and implicate new genes and pathways, including those related to synaptic function, glutamate signalling, insulin secretion/action, energy metabolism, lipid biology and adipogenesis.
|
|
| 2. |
- Berglund, Björn, et al.
(author)
-
Efficient removal of antibiotics in surface-flow constructed wetlands, with no observed impact on antibiotic resistance genes
- 2014
-
In: Science of the Total Environment. - Amsterdam : Elsevier. - 0048-9697 .- 1879-1026. ; 476-477, s. 29-37
-
Journal article (peer-reviewed)abstract
- Recently, there have been growing concerns about pharmaceuticals including antibiotics as environmental contaminants. Antibiotics of concentrations commonly encountered in wastewater have been suggested to affect bacterial population dynamics and to promote dissemination of antibiotic resistance. Conventional wastewater treatment processes do not always adequately remove pharmaceuticals causing environmental dissemination of low levels of these compounds. Using constructed wetlands as an additional treatment step after sewage treatment plants have been proposed as a cheap alternative to increase reduction of wastewater contaminants, however this means that the natural microbial community of the wetlands becomes exposed to elevated levels of antibiotics. In this study, experimental surface-flow wetlands in Sweden were continuously exposed to antibiotics of concentrations commonly encountered in wastewater. The aim was to assess the antibiotic removal efficiency of constructed wetlands and to evaluate the impact of low levels of antibiotics on bacterial diversity, resistance development and expression in the wetland bacterial community. Antibiotic concentrations were measured using liquid chromatography-mass spectrometry and the effect on the bacterial diversity was assessed with 16S rRNA-based denaturing gradient gel electrophoresis. Real-time PCR was used to detect and quantify antibiotic resistance genes and integrons in the wetlands, during and after the exposure period. The results indicated that the antibiotic removal efficiency of constructed wetlands was comparable to conventional wastewater treatment schemes. Furthermore, short-term treatment of the constructed wetlands with environmentally relevant concentrations (i.e. 100-2000 ng x 1(-1)) of antibiotics did not significantly affect resistance gene concentrations, suggesting that surface-flow constructed wetlands are well-suited for wastewater treatment purposes. (c) 2014 Elsevier B.V. All rights reserved.
|
|
| 3. |
|
|
| 4. |
- Berndt, Sonja I., et al.
(author)
-
Genome-wide meta-analysis identifies 11 new loci for anthropometric traits and provides insights into genetic architecture
- 2013
-
In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 45:5, s. 501-U69
-
Journal article (peer-reviewed)abstract
- Approaches exploiting trait distribution extremes may be used to identify loci associated with common traits, but it is unknown whether these loci are generalizable to the broader population. In a genome-wide search for loci associated with the upper versus the lower 5th percentiles of body mass index, height and waist-to-hip ratio, as well as clinical classes of obesity, including up to 263,407 individuals of European ancestry, we identified 4 new loci (IGFBP4, H6PD, RSRC1 and PPP2R2A) influencing height detected in the distribution tails and 7 new loci (HNF4G, RPTOR, GNAT2, MRPS33P4, ADCY9, HS6ST3 and ZZZ3) for clinical classes of obesity. Further, we find a large overlap in genetic structure and the distribution of variants between traits based on extremes and the general population and little etiological heterogeneity between obesity subgroups.
|
|
| 5. |
- Börjesson, Stefan, et al.
(author)
-
Quantification of genes encoding resistance to aminoglycosides, beta-lactams and tetracyclines in wastewater environments by real-time PCR
- 2009
-
In: International Journal of Environmental Health Research. - : Informa UK Limited. - 0960-3123 .- 1369-1619. ; 19:3, s. 219-30
-
Journal article (peer-reviewed)abstract
- In this study real-time PCR assays, based on the LUX-technique, were developed for quantification of genes mediating resistance to aminoglycosides [aac(6 ')-Ie + aph(2 ' ')], beta-lactams (mecA), and tetracyclines (tetA and tetB), for use in wastewater environments. The developed assays were applied on DNA extracted from three wastewater-associated environments: soil from an overland flow area treating landfill leachates, biofilm from a municipal wastewater treatment plant, and sludge from a hospital wastewater pipeline. The highest concentration of all genes was observed in the hospital pipeline and the lowest in the overland flow system. TetA and aac(6 ')-Ie + aph(2 ' ') could be detected in all environments. The tetB gene was detected in the overland flow area and the hospital wastewater pipeline and mecA was detected in the wastewater treatment plant and the hospital pipeline. The developed LUX real-time PCR assays were shown to be fast and reproducible tools for detection and quantification of the four genes encoding antibiotic resistance in wastewater.
|
|
| 6. |
- Börjesson, Stefan, 1979-, et al.
(author)
-
Quantification of genes encoding resistance to aminoglycosides, β-lactams and tetracyclines in wastewater environments by real-time PCR
- 2009
-
In: International Journal of Environmental Health Research. - : Taylor & Francis. - 0960-3123 .- 1369-1619. ; 19:3, s. 219-230
-
Journal article (peer-reviewed)abstract
- In this study real-time PCR assays, based on the LUX™-technique, were developed for quantification of genes mediating resistance to aminoglycosides [aac(6´′)-Ie + aph(2´′´′)], β-lactams (mecA), and tetracyclines (tetA and tetB), for use in wastewater environments. The developed assays were applied on DNA extracted from three wastewater-associated environments: soil from an overland flow area treating landfill leachates, biofilm from a municipal wastewater treatment plant, and sludge from a hospital wastewater pipeline. The highest concentration of all genes was observed in the hospital pipeline and the lowest in the overland flow system. TetA and aac(6´′)-Ie + aph(2´′´′) could be detected in all environments. The tetB gene was detected in the overland flow area and the hospital wastewater pipeline and mecA was detected in the wastewater treatment plant and the hospital pipeline. The developed LUX™ real-time PCR assays were shown to be fast and reproducible tools for detection and quantification of the four genes encoding antibiotic resistance in wastewater.
|
|
| 7. |
|
|
| 8. |
- Lango Allen, Hana, et al.
(author)
-
Hundreds of variants clustered in genomic loci and biological pathways affect human height.
- 2010
-
In: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 467:7317, s. 832-8
-
Journal article (peer-reviewed)abstract
- Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P<0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.
|
|
| 9. |
- Lindgren, Johan, et al.
(author)
-
Fossil insect eyes shed light on trilobite optics and the arthropod pigment screen
- 2019
-
In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 573:7772, s. 122-125
-
Journal article (peer-reviewed)abstract
- Fossilized eyes permit inferences of the visual capacity of extinct arthropods1–3. However, structural and/or chemical modifications as a result of taphonomic and diagenetic processes can alter the original features, thereby necessitating comparisons with modern species. Here we report the detailed molecular composition and microanatomy of the eyes of 54-million-year-old crane-flies, which together provide a proxy for the interpretation of optical systems in some other ancient arthropods. These well-preserved visual organs comprise calcified corneal lenses that are separated by intervening spaces containing eumelanin pigment. We also show that eumelanin is present in the facet walls of living crane-flies, in which it forms the outermost ommatidial pigment shield in compound eyes incorporating a chitinous cornea. To our knowledge, this is the first record of melanic screening pigments in arthropods, and reveals a fossilization mode in insect eyes that involves a decay-resistant biochrome coupled with early diagenetic mineralization of the ommatidial lenses. The demonstrable secondary calcification of lens cuticle that was initially chitinous has implications for the proposed calcitic corneas of trilobites, which we posit are artefacts of preservation rather than a product of in vivo biomineralization4–7. Although trilobite eyes might have been partly mineralized for mechanical strength, a (more likely) organic composition would have enhanced function via gradient-index optics and increased control of lens shape.
|
|
| 10. |
- Speliotes, Elizabeth K., et al.
(author)
-
Association analyses of 249,796 individuals reveal 18 new loci associated with body mass index
- 2010
-
In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:11, s. 937-948
-
Journal article (peer-reviewed)abstract
- Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ~2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10−8), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation.
|
|
| 11. |
- Wuttke, Matthias, et al.
(author)
-
A catalog of genetic loci associated with kidney function from analyses of a million individuals
- 2019
-
In: Nature Genetics. - : NATURE PUBLISHING GROUP. - 1061-4036 .- 1546-1718. ; 51:6, s. 957-972
-
Journal article (peer-reviewed)abstract
- Chronic kidney disease (CKD) is responsible for a public health burden with multi-systemic complications. Through transancestry meta-analysis of genome-wide association studies of estimated glomerular filtration rate (eGFR) and independent replication (n = 1,046,070), we identified 264 associated loci (166 new). Of these,147 were likely to be relevant for kidney function on the basis of associations with the alternative kidney function marker blood urea nitrogen (n = 416,178). Pathway and enrichment analyses, including mouse models with renal phenotypes, support the kidney as the main target organ. A genetic risk score for lower eGFR was associated with clinically diagnosed CKD in 452,264 independent individuals. Colocalization analyses of associations with eGFR among 783,978 European-ancestry individuals and gene expression across 46 human tissues, including tubulo-interstitial and glomerular kidney compartments, identified 17 genes differentially expressed in kidney. Fine-mapping highlighted missense driver variants in 11 genes and kidney-specific regulatory variants. These results provide a comprehensive priority list of molecular targets for translational research.
|
|
| 12. |
- Aase, Audun, et al.
(author)
-
Validate or falsify: Lessons learned from a microscopy method claimed to be useful for detecting Borrelia and Babesia organisms in human blood
- 2016
-
In: INFECTIOUS DISEASES. - : TAYLOR & FRANCIS LTD. - 2374-4235 .- 2374-4243. ; 48:6, s. 411-419
-
Journal article (peer-reviewed)abstract
- Background A modified microscopy protocol (the LM-method) was used to demonstrate what was interpreted as Borrelia spirochetes and later also Babesia sp., in peripheral blood from patients. The method gained much publicity, but was not validated prior to publication, which became the purpose of this study using appropriate scientific methodology, including a control group. Methods Blood from 21 patients previously interpreted as positive for Borrelia and/or Babesia infection by the LM-method and 41 healthy controls without known history of tick bite were collected, blinded and analysed for these pathogens by microscopy in two laboratories by the LM-method and conventional method, respectively, by PCR methods in five laboratories and by serology in one laboratory. Results Microscopy by the LM-method identified structures claimed to be Borrelia- and/or Babesia in 66% of the blood samples of the patient group and in 85% in the healthy control group. Microscopy by the conventional method for Babesia only did not identify Babesia in any samples. PCR analysis detected Borrelia DNA in one sample of the patient group and in eight samples of the control group; whereas Babesia DNA was not detected in any of the blood samples using molecular methods. Conclusions The structures interpreted as Borrelia and Babesia by the LM-method could not be verified by PCR. The method was, thus, falsified. This study underlines the importance of doing proper test validation before new or modified assays are introduced.
|
|
| 13. |
- Adams, Yvonne, et al.
(author)
-
3D blood-brain barrier-organoids as a model for Lyme neuroborreliosis highlighting genospecies dependent organotropism
- 2023
-
In: ISCIENCE. - : CELL PRESS. - 2589-0042. ; 26:1
-
Journal article (peer-reviewed)abstract
- Lyme neuroborreliosis (LNB), a tick-borne infection caused by spirochetes within the Borrelia burgdorferi sensu lato (s.L.) complex, is among the most prevalent bacterial central nervous system (CNS) infections in Europe and the US. Here we have screened a panel of low- passage B. burgdorferi s.l. isolates using a novel, human-derived 3D blood-brain barrier (BBB)-organoid model. We show that human-derived BBB-organoids support the entry of Borrelia spirochetes, leading to swelling of the organoids and a loss of their structural integrity. The use of the BBB-organoid model highlights the organotropism between B. burgdorferi s.l. genospecies and their ability to cross the BBB contributing to CNS infection.
|
|
| 14. |
- Almstrand, Robert, et al.
(author)
-
Dynamics of specific ammonia-oxidizing bacterial populations and nitrification in response to controlled shifts of ammonium concentrations in wastewater
- 2013
-
In: Applied Microbiology and Biotechnology. - : Springer Verlag (Germany). - 0175-7598 .- 1432-0614. ; 97:5, s. 2183-2191
-
Journal article (peer-reviewed)abstract
- Ammonia-oxidizing bacteria (AOB) are essential for the nitrification process in wastewater treatment. To retain these slow-growing bacteria in wastewater treatment plants (WWTPs), they are often grown as biofilms, e.g., on nitrifying trickling filters (NTFs) or on carriers in moving bed biofilm reactors (MBBRs). On NTFs, a decreasing ammonium gradient is formed because of the AOB activity, resulting in low ammonium concentrations at the bottom and reduced biomass with depth. To optimize the NTF process, different ammonium feed strategies may be designed. This, however, requires knowledge about AOB population dynamics. Using fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy, we followed biomass changes during 6 months, of three AOB populations on biofilm carriers. These were immersed in aerated MBBR tanks in a pilot plant receiving full-scale wastewater. Tanks were arranged in series, forming a wastewater ammonium gradient mimicking an NTF ammonium gradient. The biomass of one of the dominating Nitrosomonas oligotropha-like populations increased after an ammonium upshift, reaching levels comparable to the high ammonium control in 28 days, whereas a Nitrosomonas europaea-like population increased relatively slowly. The MBBR results, together with competition studies in NTF systems fed with wastewater under controlled ammonium regimes, suggest a differentiation between the two N. oligotropha populations, which may be important for WWTP nitrification.
|
|
| 15. |
- Andersson, Martin O., et al.
(author)
-
Molecular detection of Babesia capreoli and Babesia venatorum in wild Swedish roe deer, Capreolus capreolus
- 2016
-
In: Parasites & Vectors. - : Springer Science and Business Media LLC. - 1756-3305. ; 9:1
-
Journal article (peer-reviewed)abstract
- Background: The epidemiology of the zoonotic tick-transmitted parasite Babesia spp. and its occurrence in wild reservoir hosts in Sweden is unclear. In European deer, several parasite species, including Babesia capreoli and the zoonotic B. venatorum and B. divergens has been reported previously. The European roe deer, Capreolus capreolus, is an important and common part of the indigenous fauna in Europe, as well as an important host for Ixodes ricinus ticks, the vector of several Babesia spp. in Europe. Here, we aimed to investigate the occurrence of Babesia spp. in roe deer in Sweden. Findings: Roe deer (n = 77) were caught and sampled for blood. Babesia spp. was detected with a PCR assay targeting the 18S rRNA gene. The prevalence of Babesia spp. was 52 %, and two species were detected; B. capreoli and B. venatorum in 44 and 7.8 % of the individuals, respectively. Infection occurred both in summer and winter. Conclusions: We showed that roe deer in Sweden, close to the edge of their northern inland distributional range, are infected with Babesia spp. The occurrence of B. venatorum in roe deer imply that it is established in Sweden and the zoonotic implication of this finding should be regarded to a greater extent in future.
|
|
| 16. |
- Asghar, Naveed, et al.
(author)
-
Tick-borne encephalitis virus sequenced directly from questing and blood-feeding ticks reveals quasispecies variance.
- 2014
-
In: PLOS ONE. - San Francisco, USA : Public Library of Science (PLoS). - 1932-6203. ; 9:7
-
Journal article (peer-reviewed)abstract
- The increased distribution of the tick-borne encephalitis virus (TBEV) in Scandinavia highlights the importance of characterizing novel sequences within the natural foci. In this study, two TBEV strains: the Norwegian Mandal 2009 (questing nymphs pool) and the Swedish Saringe 2009 (blood-fed nymph) were sequenced and phylogenetically characterized. Interestingly, the sequence of Mandal 2009 revealed the shorter form of the TBEV genome, similar to the highly virulent Hypr strain, within the 3' non-coding region (3'NCR). A different genomic structure was found in the 3'NCR of Saringe 2009, as in-depth analysis demonstrated TBEV variants with different lengths within the poly(A) tract. This shows that TBEV quasispecies exists in nature and indicates a putative shift in the quasispecies pool when the virus switches between invertebrate and vertebrate environments. This prompted us to further sequence and analyze the 3'NCRs of additional Scandinavian TBEV strains and control strains, Hypr and Neudoerfl. Toro 2003 and Habo 2011 contained mainly a short (A)3C(A)6 poly(A) tract. A similar pattern was observed for the human TBEV isolates 1993/783 and 1991/4944; however, one clone of 1991/4944 contained an (A)3C(A)11 poly(A) sequence, demonstrating that quasispecies with longer poly(A) could be present in human isolates. Neudoerfl has previously been reported to contain a poly(A) region, but to our surprise the re-sequenced genome contained two major quasispecies variants, both lacking the poly(A) tract. We speculate that the observed differences are important factors for the understanding of virulence, spread, and control of the TBEV.
|
|
| 17. |
- Augustinsson (Nilsdotter-Augustinsson), Åsa, 1962-, et al.
(author)
-
Interaction of staphylococcus epidermidis from infected hip prostheses with neutrophil granulocytes
- 2001
-
In: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 33:6, s. 408-412
-
Journal article (peer-reviewed)abstract
- This study focuses on the interaction of Staphylococcus epidermis isolated from granulation tissue covering infected hip prostheses and neutrophil granulocytes. Bacterial strains isolated from normal flora were used as controls. The bacteria were well characterized with routine methods and further characterized with random amplified polymorphic DNA analyses and slime tests. Phagocytosis and chemiluminescence (CL) assays were used in the neutrophil interaction studies. The prostheses strains were ingested to a lesser extent than strains from normal flora (p ≤ 0.001). There was no significant difference between the prostheses strains and the normal flora strains in terms of total CL response. However, the extracellular CL response from the neutrophils was lower in comparison with the normal flora when interacting with the prostheses strains. The results of this study support the notion that S. epidermidis strains isolated from infected hip prostheses have an enhanced capacity to resist phagocytosis and that most of these strains elicit a reduced inflammatory response, measured as the production of extracellular oxidative metabolites from the neutrophils, compared to normal flora.
|
|
| 18. |
- Berglund, Björn, et al.
(author)
-
Abundance and dynamics of antibiotic resistance genes and integrons in lake sediment microcosms
- 2014
-
In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9
-
Journal article (peer-reviewed)abstract
- Antibiotic resistance in bacteria causing disease is an ever growing threat to the world. Recently, environmental bacteria have become established as important both as sources of antibiotic resistance genes and in disseminating resistance genes. Low levels of antibiotics and other pharmaceuticals are regularly released into water environments via wastewater, and the concern is that such environmental contamination may serve to create hotspots for antibiotic resistance gene selection and dissemination. In this study, microcosms were created from water and sediments gathered from a lake in Sweden only lightly affected by human activities. The microcosms were exposed to a mixture of antibiotics of varying environmentally relevant concentrations (i.e., concentrations commonly encountered in wastewaters) in order to investigate the effect of low levels of antibiotics on antibiotic resistance gene abundances and dynamics in a previously uncontaminated environment. Antibiotic concentrations were measured using liquid chromatography-tandem mass spectrometry. Abundances of seven antibiotic resistance genes and the class 1 integron integrase gene, intL1, were quantified using real-time PCR. Resistance genes sulI and ermB were quantified in the microcosm sediments with mean abundances 5 and 15 gene copies/10(6) 16S rRNA gene copies, respectively. Class 1 integrons were determined in the sediments with a mean concentration of 3.86x10(4) copies/10(6) 16S rRNA gene copies. The antibiotic treatment had no observable effect on antibiotic resistance gene or integron abundances.
|
|
| 19. |
- Berglund, Björn, 1983-
(author)
-
Deliberations on the impact of antibiotic contamination on dissemination of antibiotic resistance genes in aquatic environments
- 2014
-
Doctoral thesis (other academic/artistic)abstract
- The great success of antibiotics in treating bacterial infectious diseases has been hampered by the increasing prevalence of antibiotic resistant bacteria. Not only does antibiotic resistance threaten to increase the difficulty in treating bacterial infectious diseases, but it could also make medical procedures such as routine surgery and organ transplantations very dangerous to perform. Traditionally, antibiotic resistance has been regarded as a strictly clinical problem and studies of the problem have mostly been restricted to a clinical milieu. Recently, non-clinical environments, and in particular aquatic environments, have been recognised as important factors in development and dissemination of antibiotic resistance. Elevated concentrations of antibiotics in an environment are likely to drive a selection pressure which favours resistant bacteria, and are also believed to promote horizontal gene transfer among the indigenous bacteria. Antibiotic resistance genes are often located on mobile genetic elements such as plasmids and integrons, which have the ability to disseminate among taxonomically unrelated species. The environmental bacteria can thus serve as both reservoirs for resistance and hot spots for the development of new antibiotic resistance determinants.There is still a lack of data pertaining to how high antibiotic concentrations are necessary to drive a selection pressure in aquatic environments. The aim of this thesis is to determine the effect of high and low concentrations of antibiotics on environmental bacterial communities from different aquatic environments. In the studies performed, antibiotics were measured using liquid chromatography-mass spectrometry. Bacterial diversity and evenness were assessed using molecular fingerprints obtained with 16S rRNA gene-based denaturing gradient gel electrophoresis, and antibiotic resistance genes and class 1 integrons were quantified using real-time PCR.Water and sediment samples were collected from different rivers and canals in Pakistan. The environments differed in anthropogenic exposure from undisturbed to heavily contaminated. A general trend could be observed of high concentrations of antibiotics correlating to elevated concentrations of antibiotic resistance genes and integrons. Extremely high concentrations of antibiotic resistance genes and integrons were found in the sediments downstream of an industrial drug formulation site, which likely correlated to the high load of antibiotics found in the water. Antibiotic and antibiotic resistance gene concentrations were also shown to increase downstream of Ravi river, which flows through Lahore, a city of more than 10 million inhabitants. Rivers not impacted by anthropogenic contamination were found to contain antibiotics and resistance gene concentrations of similar levels as in Europe and the U.S. Similar measurements were performed in the Swedish river Stångån. The concentrations of antibiotic resistance genes and class 1 integrons were shown to increase in the river after it had passed, and received urban wastewater effluent from the city of Linköping.A series of constructed wetlands were exposed to a mixture of different antibiotics at environmentally relevant concentrations over a few weeks. The antibiotic exposure did not observably affect the bacterial diversity or integron concentrations. Antibiotic resistance genes were found at low background concentrations, but the antibiotic exposure did not observably affect the concentrations. The constructed wetlands were also found to reduce most antibiotics at levels comparable to conventional wastewater treatment schemes, suggesting that constructed wetlands may be useful supplementary alternatives to conventional wastewater treatment.To investigate the effect of antibiotics on an uncontaminated aquatic environment in a more controlled setting, microcosms were constructed from lake water and sediments and subsequently exposed to varying concentrations of antibiotics (ranging from wastewater-like concentrations to 1,000 times higher). The water and sediments were gathered from the lake Nydalasjön, near Umeå, which is not exposed to urban waste. While antibiotic resistance genes and class 1 integrons were found in the lake sediments, no increase in the concentrations of these genes could be observed due to the antibiotic additions.In conclusion, although antibiotic resistance genes and integrons are part of the environmental gene pool, low concentrations of antibiotics do not seem to immediately impact their prevalence. However, aquatic environments exposed to anthropogenic waste do exhibit elevated levels of antibiotic resistance genes and integrons. Aquatic environments heavily polluted with antibiotics also clearly display correspondingly high concentrations of antibiotic resistance genes and integrons. These results clearly indicate the necessity to keep down pollution levels as well as the need to establish the range of antibiotic concentrations which do promote resistance. This must be done in order to enable risk assessments and to establish acceptable levels of antibiotic pollution. It should also be stressed that more research is required to elucidate what effect low levels of antibiotic exposure has on environmental bacterial communities.
|
|
| 20. |
- Berglund, Björn, et al.
(author)
-
Detection and Quantification of Antibiotic Resistance Genes in Stångån River, Sweden
- 2014
-
Other publication (other academic/artistic)abstract
- Antibiotic resistant bacteria are an emerging global problem which threatens to undermine important advances in modern medicine. It is becoming increasingly clear that the dynamics of antibiotic resistance are not confined to clinical settings. The environment is likely to play an important role in dissemination of antibiotic resistance genes from and to both environmental and pathogenic bacteria. Wastewater treatment plants accumulate both chemical and biological waste from the surrounding urban milieu and have therefore been viewed as potential hotspots for dissemination and development of antibiotic resistance. To assess the effect of wastewater effluent on a river which flows through a Swedish city, sediment and water samples were collected from Stångån River, both upstream and downstream of an adjacent wastewater treatment plant over three months. Seven antibiotic resistance genes and the integrase gene on class 1 integrons were quantified in the collected sediment using realtime PCR. Furthermore, liquid chromatography-mass spectrometry was used to assess the abundance of ten different antibiotics in the water phase of the samples. The results showed an increase in ARGs and integrons downstream of the wastewater treatment plant as compared to upstream. The measured concentrations of antibiotics were low in the water samples from Stångån River, suggesting that selection for antibiotic resistance genes did not occur in the surface water. Instead, the downstream increase in antibiotic resistance genes is likely to be due to accumulation of genes present in the treated effluent discharged from the wastewater treatment plant.
|
|
| 21. |
- Berglund, Björn, et al.
(author)
-
Occurrence and removal efficiency of parasitic protozoa in Swedish wastewater treatment plants
- 2017
-
In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 598, s. 821-827
-
Journal article (peer-reviewed)abstract
- Giardia intestinalis, Cryptosporidium spp., Entamoeba histolytica and Dientamoeba fragilis are parasitic protozoa and causative agents of gastroenteritis in humans. G. intestinalis and Cryptosporidium spp. in particular are the most common protozoa associated with waterborne outbreaks in high-income countries. Surveillance of protozoan prevalence in wastewater and evaluation of wastewater treatment removal efficiencies of protozoan pathogens is therefore imperative for assessment of human health risk. In this study, influent and effluent wastewater samples from three wastewater treatment plants in Sweden were collected over nearly one year and assessed for prevalence of parasitic protozoa. Quantitative real-time PCR using primers specific for the selected protozoa Cryptosporidium spp., G. intestinalis, E. histolytica, Entamoeba dispar and D. fragilis was used for protozoan DNA detection and assessment of wastewater treatment removal efficiencies. Occurrence of G. intestinalis, E. dispar and D. fragilis DNA was assessed in both influent (44, 30 and 39 out of 51 samples respectively) and effluent wastewater (14, 9 and 33 out of 51 samples respectively) in all three wastewater treatment plants. Mean removal efficiencies of G. intestinalis, E. dispar and D. fragilis DNA quantities, based on all three wastewater treatment plants studied varied between 67 and 87%, 37–75% and 20–34% respectively. Neither E. histolytica nor Cryptosporidium spp. were detected in any samples. Overall, higher quantities of protozoan DNA were observed from February to June 2012. The high prevalence of protozoa in influent wastewater indicates the need for continued monitoring of these pathogens in wastewater-associated aquatic environments to minimise the potential risk for human infection.
|
|
| 22. |
- Berglund, Björn, et al.
(author)
-
Urban wastewater effluent increases antibiotic resistance gene concentrations in a receiving northern european river
- 2015
-
In: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 34:1, s. 192-196
-
Journal article (peer-reviewed)abstract
- Antibiotic-resistant bacteria are an emerging global problem that threatens to undermine important advances in modern medicine. The environment is likely to play an important role in the dissemination of antibiotic-resistance genes (ARGs) among both environmental and pathogenic bacteria. Wastewater treatment plants (WWTPs) accumulate both chemical and biological waste from the surrounding urban milieu and have therefore been viewed as potential hotspots for dissemination and development of antibiotic resistance. To assess the effect of wastewater effluent on a river that flows through a Swedish city, sediment and water samples were collected from Stangan River, both upstream and downstream of an adjacent WWTP over 3 mo. Seven ARGs and the integrase gene on class 1 integrons were quantified in the collected sediment using real-time polymerase chain reaction (PCR). Liquid chromatography-mass spectrometry was used to assess the abundance of 10 different antibiotics in the water phase of the samples. The results showed an increase in ARGs and integrons downstream of the WWTP. The measured concentrations of antibiotics were low in the water samples from the Stangan River, suggesting that selection for ARGs did not occur in the surface water. Instead, the downstream increase in ARGs is likely to be attributable to accumulation of genes present in the treated effluent discharged from the WWTP. Environ Toxicol Chem 2015;34:192-196. (c) 2014 SETAC
|
|
| 23. |
- Borg, O., et al.
(author)
-
Expansion of spatial and host range of Puumala virus in Sweden : an increasing threat for humans?
- 2017
-
In: Epidemiology and Infection. - : Cambridge University Press. - 0950-2688 .- 1469-4409. ; 145:8, s. 1642-1648
-
Journal article (peer-reviewed)abstract
- Hantaviruses are globally distributed and cause severe human disease. Puumala hantavirus (PUUV) is the most common species in Northern Europe, and the only hantavirus confirmed to circulate in Sweden, restricted to the northern regions of the country. In this study, we aimed to further add to the natural ecology of PUUV in Sweden by investigating prevalence, and spatial and host species infection patterns. Specifically, we wanted to ascertain whether PUUV was present in the natural reservoir, the bank vole (Myodes glareolus) further south than Dalälven river, in south-central Sweden, and whether PUUV can be detected in other rodent species in addition to the natural reservoir. In total, 559 animals were collected at Grimsö (59°43'N; 15°28'E), Sala (59°55'N; 16°36'E) and Bogesund (59°24'N; 18°14'E) in south-central Sweden between May 2013 and November 2014. PUUV ELISA-reactive antibodies were found both in 2013 (22/295) and in 2014 (18/264), and nine samples were confirmed as PUUV-specific by focus reduction neutralization test. Most of the PUUV-specific samples were from the natural host, the bank vole, but also from other rodent hosts, indicating viral spill-over. Finally, we showed that PUUV is present in more highly populated central Sweden.
|
|
| 24. |
- Borjesson, Stefan, et al.
(author)
-
Methicillin-resistant Staphylococcus aureus (MRSA) in municipal wastewater: an uncharted threat?
- 2010
-
In: JOURNAL OF APPLIED MICROBIOLOGY. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 108:4, s. 1244-1251
-
Journal article (peer-reviewed)abstract
- Aims: (i) To cultivate methicillin-resistant Staphylococcus aureus (MRSA) from a full-scale wastewater treatment plant (WWTP), (ii) To characterize the indigenous MRSA-flora, (iii) To investigate how the treatment process affects clonal distribution and (iv) To examine the genetic relation between MRSA from wastewater and clinical MRSA. Methods: Wastewater samples were collected during 2 months at four key sites in the WWTP. MRSA isolates were characterized using spa typing, antibiograms, SSCmec typing and detection of Panton-Valentine leukocidin (PVL). Conclusions: MRSA could be isolated on all sampling occasions, but only from inlet and activated sludge. The number of isolates and diversity of MRSA were reduced by the treatment process, but there are indications that the process was selected for strains with more extensive antibiotic resistance and PVL+ strains. The wastewater MRSA-flora had a close genetic relationship to clinical isolates, most likely reflecting carriage in the community. Significance and Impact of the Study: This study shows that MRSA survives in wastewater and that the WWTP may be a potential reservoir for MRSA.
|
|
| 25. |
|
|
