| 11. |
- Jernberg, Cecilia, et al.
(författare)
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Long-term ecological impacts of antibiotic administration on the human intestinal microbiota
- 2007
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Ingår i: The ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 1:1, s. 56-66
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Tidskriftsartikel (refereegranskat)abstract
- Antibiotic administration is known to cause short-term disturbances in the microbiota of the human gastrointestinal tract, but the potential long-term consequences have not been well studied. The aims of this study were to analyse the long-term impact of a 7-day clindamycin treatment on the faecal microbiota and to simultaneously monitor the ecological stability of the microbiota in a control group as a baseline for reference. Faecal samples from four clindamycin-exposed and four control subjects were collected at nine different time points over 2 years. Using a polyphasic approach, we observed highly significant disturbances in the bacterial community that persisted throughout the sampling period. In particular, a sharp decline in the clonal diversity of Bacteroides isolates, as assessed by repetitive sequence-based PCR (rep-PCR) and long-term persistence of highly resistant clones were found as a direct response to the antibiotic exposure. The Bacteroides community never returned to its original composition during the study period as assessed using the molecular fingerprinting technique, terminal restriction fragment length polymorphism (T-RFLP). Furthermore, using real-time PCR we found a dramatic and persistent increase in levels of specific resistance genes in DNA extracted from the faeces after clindamycin administration. The temporal variations in the microbiota of the control group were minor compared to the large and persistent shift seen in the exposed group. These results demonstrate that long after the selection pressure from a short antibiotic exposure has been removed, there are still persistent long term impacts on the human intestinal microbiota that remain for up to 2 years post-treatment.
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| 12. |
- Jernberg, Cecilia, et al.
(författare)
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Long-term impacts of antibiotic exposure on the human intestinal microbiota
- 2010
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Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 156, s. 3216-3223
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Forskningsöversikt (refereegranskat)abstract
- Although it is known that antibiotics have short-term impacts on the human microbiome, recent evidence demonstrates that the impacts of some antibiotics remain for extended periods of time. In addition, antibiotic-resistant strains can persist in the human host environment in the absence of selective pressure. Both molecular- and cultivation-based approaches have revealed ecological disturbances in the microbiota after antibiotic administration, in particular for specific members of the bacterial community that are susceptible or alternatively resistant to the antibiotic in question. A disturbing consequence of antibiotic treatment has been the long-term persistence of antibiotic resistance genes, for example in the human gut. These data warrant use of prudence in the administration of antibiotics that could aggravate the growing battle with emerging antibiotic-resistant pathogenic strains.
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| 13. |
- Jernberg, Cecilia, et al.
(författare)
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Monitoring of antibiotic-induced alterations in the human intestinal microflora and detection of probiotic strains by use of terminal restriction fragment length polymorphism
- 2005
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 71:1, s. 501-506
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Tidskriftsartikel (refereegranskat)abstract
- Terminal restriction fragment length polymorphism (T-RFLP) was investigated as a tool for monitoring the human intestinal microflora during antibiotic treatment and during ingestion of a probiotic product. Fecal samples from eight healthy volunteers were taken before, during, and after administration of clindamycin. During treatment, four subjects were given a probiotic, and four subjects were given a placebo. Changes in the microbial intestinal community composition and relative abundance of specific microbial populations in each subject were monitored by using viable counts and T-RFLP fingerprints. T-RFLP was also used to monitor specific bacterial populations that were either positively or negatively affected by clindamycin. Some dominant bacterial groups, such as Eubacterium spp., were easily monitored by T-RFLP, while they were hard to recover by cultivation. Furthermore, the two probiotic Lactobacillus strains were easily tracked by T-RFLP and were shown to be the dominant Lactobacillus community members in the intestinal microflora of subjects who received the probiotic.
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| 14. |
- Jernberg, Cecilia
(författare)
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Use of microbiomics to study human impacts on complex microbial communities
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of bacterial communities in nature is currently a challenge. The majority of bacteria in clinical and environmental samples have not yet been cultured and therefore we cannot fully understand their roles in nature and how the ecological balance in a specific microbial ecosystem can be disrupted. For example, exposure to pollutants in soil and antibiotics in the human gut can have large consequences on microbial populations but the magnitude of these impacts is difficult to assess. In this thesis, a combination of molecular techniques, microbiomics, were used to assess complex microbial communities in soil and the human gut. One goal of this thesis was to study the impact of the toxic compound, 4-chlorophenol, on the soil microbiota. In addition, a specific 4-chlorophenol degrading bacterium, Arthrobacter chlorophenolicus, was monitored in soil. In order to monitor the cells they were chromosomally tagged with marker genes encoding either the green fluorescent protein (the gfp gene) or firefly luciferase (the luc gene). During degradation of high levels of 4-chlorophenol in soil, total cells counts of A. chlorophenolicus cells could be measured by flow cytometry (GFP protein) and the metabolic activity could be measured by lurninometry (luciferase activity). In addition, the relative abundance of A. chlorophenolicus in soil could be measured by terminal restriction fragment length polymorphism (T-RFLP) and a higher relative abundance was detected in soil contaminated with 4chlorophenol compared with non-treated soil. The impacts of 4-chlorophenol and A. chlorophenolicus on the dominant members of the soil microbiota were also assessed by T-RFLP. Another goal of this thesis was to study the impact of a short term antibiotic administration in a long term perspective, using either clindamycin, in a two year study or a triple therapy for eradication of Helicobacter pylori containing clarithromycin and metronidazole, in a four year study, on the human fecal microbiota. Both the total bacterial community and specific populations, i.e. Bacteroides spp. and Enterococcus spp., were monitored by T-RFLP. The Bacteroides populations never returned to their pre-treatment composition after clindamycin exposure during the two year study period. Selection and persistence of resistant Bacteroides clones up to two years after treatment was furthermore detected. In the four year study, Enterococcus populations increased as a response to the clarithromycin and metronidazole treatment. An increase in the levels of antibiotic resistance genes, specific erm genes, conferring resistance to macrolides and lincosamides were detected for up to 2 and 4 years after both types of antibiotic treatments in the respective studies. It was also possible to specifically monitor two probiotic Lactobacillus strains and their transient colonization by T-RFLP. In conclusion, the use of a polyphasic approach with complementary analytical tools made it possible to obtain a comprehensive picture of complex microbial communities. In addition, specific bacteria of interest in complex soil and fecal samples could be monitored using microbiomics approaches.
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| 15. |
- Karlsson, Philip A., et al.
(författare)
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Molecular Characterization of Multidrug-Resistant Yersinia enterocolitica From Foodborne Outbreaks in Sweden
- 2021
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The foodborne pathogen Yersinia enterocolitica causes gastrointestinal infections worldwide. In the spring of 2019, the Swedish Public Health Agency and Statens Serum Institut in Denmark independently identified an outbreak caused by Yersinia enterocolitica 4/O:3 that after sequence comparison turned out to be a cross-border outbreak. A trace-back investigation suggested shipments of fresh prewashed spinach from Italy as a common source for the outbreak. Here, we determined the genome sequences of five Y. enterocolitica clinical isolates during the Swedish outbreak using a combination of Illumina HiSeq short-read and Nanopore Technologies’ MinION long-read whole-genome sequencing. WGS results showed that all clinical strains have a fully assembled chromosome of approximately 4.6 Mbp in size and a 72-kbp virulence plasmid; one of the strains was carrying an additional 5.7-kbp plasmid, pYE-tet. All strains showed a high pathogen probability score (87.5%) with associated genes for virulence, all of which are closely related to an earlier clinical strain Y11 from Germany. In addition, we identified a chromosomally encoded multidrug-resistance cassette carrying resistance genes against chloramphenicol (catA1), streptomycin (aadA1), sulfonamides (sul1), and a mercury resistance module. This chromosomally encoded Tn2670 transposon has previously been reported associated with IncFII plasmids in Enterobacteriaceae: a Shigella flexneri clinical isolate from Japan in 1950s, a Klebsiella pneumoniae outbreak from Australia in 1997, and Salmonella enterica serovar Typhimurium. Interestingly, we identified an additional 5.7-kbp plasmid with tetB (encoding an ABC transporter), Rep, and its own ORI and ORIt sites, sharing high homology with small tetB-Rep plasmids from Pasteurellaceae. This is the first time that Tn2670 and Pasteurellaceae plasmids have been reported in Y. enterocolitica. Taken together, our study showed that the Swedish Y. enterocolitica outbreak strains acquired multi-antibiotic and metal-resistance genes through horizontal gene transfer, suggesting a potential reservoir of intraspecies dissemination of multidrug-resistance genes among foodborne pathogens. This study also highlights the concern of food-chain contamination of prewashed vegetables as a perpetual hazard against public health.
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| 16. |
- Karlsson, Philip, et al.
(författare)
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Complete Genome Assembly of Multidrug-Resistant Yersinia enterocolitica Y72, Isolated in Sweden
- 2021
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Ingår i: Microbiology Resource Announcements. - : American Society for Microbiology. - 2576-098X. ; 10:19
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Tidskriftsartikel (refereegranskat)abstract
- Here, we report the complete genome sequence of a Swedish clinicalstrain of Yersinia enterocolitica, Y72. With emerging Yersinia outbreaks circulating inNordic countries, the Y72 genome will provide more insights on the genetic relatedness and antibiotic resistance dissemination in future studies.
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| 17. |
- Löfmark, Sonja, et al.
(författare)
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Clindamycin-induced enrichment and long-term persistence of resistant Bacteroides spp. and resistance genes
- 2006
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 58:6, s. 1160-1167
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim was to study the long-term consequences of 1 week clindamycin administration regarding selection and persistence of resistance, resistance determinants and diversity of the Bacteroides spp. in the intestinal microflora. Methods: A total of 1306 Bacteroides isolates were collected from constitutively cultured faecal samples during a 2 year period from eight healthy volunteers. The strains were identified by biochemical and genotyping methods. MIC values were determined by the agar dilution method and presence of resistance genes was screened by real-time PCR. Results: Ecological changes in the intestinal microflora persisting up to 24 months were recorded after a 7 day clindamycin administration to four healthy volunteers. Compared to a control group, not exposed to clindamycin, an enrichment and stabilization of resistant Bacteroides strains and resistance determinants were discovered up to 2 years after clindamycin exposure. Conclusions: The results indicate that even a short-term antibiotic administration can cause long-term alterations in the commensal microbiota of individual subjects, detectable 2 years after dosing. The recorded selection and persistence of resistant strains and resistance genes, illustrates the importance of increasing our knowledge of the role of the abundant intestinal microbial community as a reservoir for spread of resistance.
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| 18. |
- Löfmark, Sonja, et al.
(författare)
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Restored fitness leads to long-term persistence of resistant Bacteroides strains in the human intestine
- 2008
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Ingår i: Anaerobe. - : Elsevier BV. - 1075-9964 .- 1095-8274. ; 14:3, s. 157-160
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Tidskriftsartikel (refereegranskat)abstract
- Acquired antibiotic resistance typically confers a cost to the bacteria, but these costs can be reduced by genetic compensation over time. The fitness of two Bacteroides thetaiotaomicron clones consecutively isolated in vivo was studied using an in vitro pair-wise competition method. The isolates derived from faecal samples of two clindamycin-exposed healthy volunteers and the two B. thetaiotaomicron clone types could be followed up to 18 months in these two subjects. The two clones were originally susceptible to clindamycin and lacked erm genes; however, after 7 days of clindamycin administration they carried the erm (erythromycin methylase)(G) or (F) gene, respectively, and expressed phenotypic clindamycin resistance. The initial cost of acquired resistance was high as seen in the in vitro pair-wise competition experiments. At 2 weeks post-administration, no growth disadvantage was detected for isolates of either of the two clones in the in vitro experiments and this regained fitness remained for isolates collected up to 18 months. Competition analysis of an in vitro isolated erm(G) positive transconjugant also demonstrated an initial reduction of fitness that was restored over time. The results indicate that the biological cost associated with a resistance gene can rapidly be compensated during in vivo growth. Thus, once the resistant clone has gained its resistance determinant it will be difficult to eliminate.
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| 19. |
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| 20. |
- Schönning, Caroline, et al.
(författare)
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Legionellosis acquired through a dental unit : a case study
- 2017
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Ingår i: Journal of Hospital Infection. - : Elsevier BV. - 0195-6701 .- 1532-2939. ; 96:1, s. 89-92
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Tidskriftsartikel (refereegranskat)abstract
- In 2012, an elderly immunocompromised man died from legionellosis at a hospital in Uppsala, Sweden. The patient had visited a dental ward at the hospital during the incubation period. Legionella spp. at a concentration of 2000 colony-forming units/L were isolated from the cupfiller outlet providing water for oral rinsing. Isolates from the patient and the dental unit were Legionella pneumophila serogroup 1, subgroup Knoxville and ST9. Pulsed-field gel electrophoresis and whole-genome sequencing strongly suggested that the isolates were of common origin. This report presents one of few documented cases of legionellosis acquired through a dental unit.
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