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| 2. |
- Agerhäll, Martin, et al.
(författare)
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High prevalence of pharyngeal bacterial pathogens among healthy adolescents and young adults
- 2021
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Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : John Wiley & Sons. - 0903-4641 .- 1600-0463. ; 129:12, s. 711-716
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Tidskriftsartikel (refereegranskat)abstract
- The pharyngeal mucosa can be colonized with bacteria that have potential to cause pharyngotonsillitis. By the use of culturing techniques and PCR, we aimed to assess the prevalence of bacterial pharyngeal pathogens among healthy adolescents and young adults. We performed a cross-sectional study in a community-based cohort of 217 healthy individuals between 16 and 25 years of age. Samples were analyzed for Group A streptococci (GAS), Group C/G streptococci (SDSE), Fusobacterium necrophorum, and Arcanobacterium haemolyticum. Compared to culturing, the PCR method resulted in more frequent detection, albeit in most cases with low levels of DNA, of GAS (20/217 vs. 5/217; p < 0.01) and F. necrophorum (20/217 vs. 8/217; p < 0.01). Culturing and PCR yielded similar rates of SDSE detection (14/217 vs. 12/217; p = 0.73). Arcanobacterium haemolyticum was rarely detected (3/217), and only by PCR. Overall, in 25.3% (55/217) of these healthy adolescents and young adults at least one of these pathogens was detected, a rate that is higher than previously described. Further studies are needed before clinical adoption of PCR-based detection methods for pharyngeal bacterial pathogens, as our findings suggest a high incidence of asymptomatic carriage among adolescents and young adults without throat infections.
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| 5. |
- Bruzzi, M, et al.
(författare)
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Radiation-hard semiconductor detectors for SuperLHC
- 2005
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 541:1-2, s. 189-201
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Tidskriftsartikel (refereegranskat)abstract
- An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016cm-2. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.
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| 6. |
- Hoffner, S, et al.
(författare)
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Proficiency of drug susceptibility testing of Mycobacterium tuberculosis against pyrazinamide: the Swedish experience
- 2013
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Ingår i: The International Journal of Tuberculosis and Lung Disease. - : International Union Against Tuberculosis and Lung Disease. - 1027-3719 .- 1815-7920. ; 17:11, s. 1486-1490
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Pyrazinamide (PZA) is a key drug in the treatment of tuberculosis (TB), including multidrug-resistant TB. Drug susceptibility testing (DST) of Mycobacterium tuberculosis against PZA is not included in the World Health Organizations yearly proficiency testing. There is an increasing need to establish quality control of PZA DST. less thanbrgreater than less thanbrgreater thanOBJECTIVE: To evaluate the performance of PZA DST and to introduce a quality assurance system for the test in Sweden. less thanbrgreater than less thanbrgreater thanMETHOD: Panels with PZA-susceptible and -resistant isolates were used in three rounds of proficiency testing in all five Swedish clinical TB laboratories and our reference laboratory. All laboratories used the MGIT 960 system. Minimum inhibitory concentrations (MICs) were determined and the pncA gene was sequenced to further characterise the 52 panel strains. less thanbrgreater than less thanbrgreater thanRESULTS: Good agreement was seen between the phenotypic PZA DST and pncA sequence data, and MIC determination confirmed high levels of resistance. However, in contrast to other drugs, for which correct proficiency test results were observed, specificity problems occurred for PZA DST in some laboratories. less thanbrgreater than less thanbrgreater thanCONCLUSIONS: In Sweden, using panel testing, differences were seen in the proficiency of TB laboratories in correctly identifying PZA susceptibility. Improved results were noted in the third round; PZA has therefore been included in yearly proficiency testing.
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| 7. |
- Hulterström, Anna Karin, et al.
(författare)
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Bacterial flora and the epidemiology of staphylococcus aureus in the nose among patients with symptomatic nasal septal perforations
- 2016
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 0001-6489 .- 1651-2251. ; 136:6, s. 620-625
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Tidskriftsartikel (refereegranskat)abstract
- Conclusions Patients with symptomatic perforations of the nasal septum had a high prevalence of S. aureus in the nasal mucosa. Pulsed field gel electrophoresis (PFGE) analysis revealed a high genetic heterogeneity of S. aureus among both patients and controls. This indicates that presence of different strains of S. aureus can maintain a chronic inflammation in symptomatic nasal septal perforations. Objective The purpose of this study was to investigate the microbial flora around nasal septal perforations in patients having severe symptoms regarding bleeding, obstruction, and crustation associated with their perforation. Methods Twenty-five patients with untreated symptomatic nasal septal perforations were included. For culture, swabs around the perforations were collected. Bacteria were identified with standard laboratory techniques including a MALDI-TOF mass spectrometer. Epidemiological analysis was done using PFGE protocols. Bacteriological data were compared with data from a healthy control group. Results Staphylococcus aureus was present in the mucosa surrounding the nasal perforation significantly more often (p < 0.0001) in the patients (88%) compared to a control group (13%). Corynebacterium spp. and Propionibacterium spp. were significantly more frequently identified in the control group. The PFGE analysis of S. aureus strains revealed a high genetic heterogeneity and no specific S. aureus genotypes were associated with septal perforation.
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| 10. |
- Hulterström, Anna Karin, 1952-, et al.
(författare)
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The microbial flora in the nasal septum area prone to perforation
- 2012
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Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - : Wiley. - 0903-4641 .- 1600-0463. ; 120:3, s. 210-214
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Tidskriftsartikel (refereegranskat)abstract
- To explore the colonizing bacterial flora of the nasal septum area, that is mostly afflicted by perforations, 101 healthy police students had swab samples taken from that location. The described culture strategy recovered positive cultures from 95% of the test subjects and from 60% with more than one organism. In total, 191 bacterial isolates were classified according to colony morphology, Gram-stain and a panel of standard laboratory techniques. A part of the bacteria was identified to species-level by biochemical methods and by sequencing of the 16S rRNA gene. The predominant finding was Gram-positive irregular rods - 65 presumptive Corynebacterium isolates, both lipophilic and non-lipophilic, and 37 anaerobic Propionibacterium isolates. The second largest bacterial group was Gram-positive catalase-positive cocci, of which 13 isolates were identified as Staphylococcus aureus and 53 as coagulase-negative staphylococci. The few potential airway pathogens included Streptococcus pneumonia (n = 1) and Moraxella catarrhalis (n = 3) isolates. The bacterial flora colonizing the nasal septum mainly consists of Gram-positive bacteria. Although of low virulence, the microbial flora may impact on occlusion treatment of nasal septum perforations with silicone obturators.
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| 11. |
- Johansson Kostenniemi, Urban, 1987-, et al.
(författare)
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Sustained reductions of invasive infectious disease following general infant Haemophilus influenzae type b and pneumococcal vaccination in a Swedish Arctic region
- 2019
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Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 108:10, s. 1871-1878
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Vaccine‐preventable pathogens causing severe childhood infections include Haemophilus influenzae type b (Hib), Streptococcus pneumoniae and Neisseria meningitidis. In this study conducted in a Swedish Arctic region, we evaluated the effects of general infant Hib and pneumococcal vaccination on invasive infectious diseases among children and assessed the need of meningococcal vaccination.Methods: We identified cases of bacterial meningitis and sepsis from diagnosis and laboratory registers in the Västerbotten Region, Sweden, during 1986–2015. We then reviewed medical records to confirm the diagnosis and extract data for assessing incidence changes, using an exploratory data analysis and a time‐series analysis.Results: Invasive Haemophilus disease declined by 89.1% (p < 0.01), Haemophilus meningitis by 95.3% (p < 0.01) and all‐cause bacterial meningitis by 82.3% (p < 0.01) in children aged 0 to four years following general infant Hib vaccination. Following pneumococcal vaccination, invasive pneumococcal disease declined by 84.7% (p < 0.01), pneumococcal meningitis by 67.5% (p = 0.16) and all‐cause bacterial meningitis by 48.0% (p = 0.23). Incidence of invasive meningococcal disease remained low during the study period.Conclusion: Remarkable sustained long‐term declines of invasive infectious diseases in younger children occurred following infant Hib and pneumococcal vaccinations in this Swedish Arctic region. Despite not offering general infant meningococcal vaccination, incidence of invasive meningococcal disease remained low.
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| 12. |
- Luan, Shi-Lu, et al.
(författare)
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Multilocus sequence typing of Swedish invasive group B streptococcus isolates indicates a neonatally associated genetic lineage and capsule switching.
- 2005
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Ingår i: Journal of clinical microbiology. - 0095-1137 .- 1098-660X. ; 43:8, s. 3727-33
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus agalactiae, also designated group B streptococcus (GBS), is an important pathogen in neonates, pregnant women, and nonpregnant adults with predisposing conditions. We used multilocus sequence typing (MLST) to characterize 158 GBS isolates that were associated with neonatal and adult invasive disease and that were collected in northern and western Sweden from 1988 to 1997. Five major genetic lineages (sequence type [ST] 19, ST-17, ST-1, ST-23, and ST-9 complexes) were identified among the isolates, including serotype Ia, Ib, and II to V isolates, indicating a highly clonal population structure among invasive GBS isolates. A number of STs were found to contain isolates of different serotypes, which indicates that capsule switching occurred rather frequently. Two distantly related genetic lineages were identified among isolates of serotype III, namely, clonal complex 19 (CC19), and CC17. CC19 was equally common among isolates from adult and neonatal disease (accounting for 10.3% of GBS isolates from adult disease and 18.7% from neonatal disease), whereas CC17 significantly appeared to be associated with neonatal invasive disease (isolated from 21.9% of neonatal isolates but only 2.6% of adult isolates). The distribution of the mobile elements GBSi1 and IS1548 reveals that they can act as genetic markers for lineages CC17 and CC19, respectively.
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| 15. |
- Olsson, Jan, et al.
(författare)
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Antibiotic susceptibility in prostate-derived Propionibacterium acnes isolates
- 2012
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Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - HOBOKEN, NJ USA : Wiley-Blackwell. - 0903-4641 .- 1600-0463. ; 120:10, s. 778-785
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine antibiotic susceptibility of Propionibacterium acnes isolates from prostate. Prostate-derived P. acnes isolates (n = 24, Umeå & Örebro, Sweden, 2007-2010) and a panel of control strains (n = 25, Sweden) collected from skin and deep infections were assessed for resistance to penicillin G, piperacillin-tazobactam, imipenem, gentamicin, azithromycin, erythromycin, vancomycin, ciprofloxacin, moxifloxacin, tetracycline, tigecycline, fusidic acid, clindamycin, rifampicin, linezolid, daptomycin, trimethoprim-sulfamethoxazole, and metronidazole. In addition, the isolates were tested for inducible clindamycin resistance. All prostate derived P. acnes isolates displayed wild-type distribution of MIC-values, without evidence of acquired resistance. In the reference panel, 5 of 25 isolates had acquired macrolide resistance with cross-resistance to azithromycin, clindamycin, and erythromycin. In addition, one of these isolates was resistant to tetracycline.
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| 17. |
- Palmgren, Helena, 1955-, et al.
(författare)
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Enteropathogenic Bacteria in Migrating Birds Arriving in Sweden
- 1997
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Scandinavian University Press. - 0036-5548 .- 1651-1980. ; 29:6, s. 565-568
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Tidskriftsartikel (refereegranskat)abstract
- Birds have been thought to play a role in transmitting infectious agents like influenza, Borrelia and Salmonella. To investigate the role of migrating birds in the dispersal of enteropathogenic bacteria, stool samples from 151 wild birds (50 gulls and 101 passerines) just entering Sweden from their winter grounds were analysed for Salmonella spp., Campylobacter spp. and EHEC O157:H7. The thermophilic isolated enteropathogens found were further analysed by antibiograms. Among the 50 gulls examined, we found 2 isolates of Salmonella typhimurium with multiple antibiotic resistance. Three isolates of C. jejuni were found in the 101 stool samples from passerines. We did not isolate EHEC O157:H7 in any of the bird stools examined.
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| 20. |
- Palmgren, Helena, 1955-, et al.
(författare)
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Salmonella in Black-headed gulls ( Larus ridibundus); prevalence, genotypes and influence on Salmonella epidemiology.
- 2006
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Ingår i: Epidemiology and Infection. - 0950-2688 .- 1469-4409. ; 134:3, s. 635-644
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Tidskriftsartikel (refereegranskat)abstract
- During a period of 3 years, 1998-2000, 1047 faecal swabs from Black-headed gulls were sampled at one location in Southern Sweden. Salmonella spp. was found in 28 individuals (2.7%) and the dominating serotype found was S. Typhimurium (83%). Twenty-five per cent of the Salmonella-infected gulls were later recaptured and re-sampled. We found that Salmonella infection in Black-headed gulls was of short duration, and that infection in this bird species was predominantly expressed as carriage without disease manifestations. All S. Typhimurium isolates were subjected to antibiotic resistance profiling and molecular characterization by pulsed-field gel electrophoresis and IS200 polymerase chain reaction. The S. Typhimurium gull isolates were compared to human and domestic animal isolates of the same serotype and phage type. We found genetic relatedness of S. Typhimurium DT195 isolates from gulls, domestic animals and humans, indicating that Black-headed gulls might play a role in the spread of S. Typhimurium in Sweden.
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| 21. |
- Palmgren, Helena, 1955-, et al.
(författare)
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Salmonella in sub-Antarctica : low heterogeneity in salmonella serotypes in South Georgian seals and birds
- 2000
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Ingår i: Epidemiology and Infection. - : Cambridge University Press. - 0950-2688 .- 1469-4409. ; 125:2, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- The number of human visitors to Antarctica is increasing rapidly, and with it a risk of introducing infectious organisms to native animals. To study the occurrence of salmonella serotypes in sub- Antarctic wildlife, faecal samples were collected from gentoo penguins, macaroni penguins, gray-headed albatrosses, black-browed albatrosses and Antarctic fur seals on Bird Island in the South Georgian archipelago during the austral summer of 1996 and 1998. In 1996, S. havana, S. typhimurium and S. enteritidis were isolated from 7% of gentoo penguins and 4% of fur seals. In 1998, however, 22% of fur seals were found to be infected with S. havana, S. enteritidis and S. newport. All isolates, except one, showed identical pulsed-field gel electrophoresis-patterns within each serotype, irrespective of sampling year and animal reservoir. No significant antibiotic resistance was found. The very low heterogeneity in the salmonella isolates found could either indicate a high genetic adaptation of the bacteria to the environment or a recent introduction of salmonella into the area.
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| 24. |
- Wilkens, Carl, 1968-
(författare)
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Auri sacra fames : Interest Rates -- Prediction, Jumps and the Market Price of Risk
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of three essays investigating different aspects of interest rates."Prediction of Future Risk-Neutral Short-Term Interest Rate Densities: Can the Black, Derman and Toy Model Assist?" (Co-authored with David Vestin.) This essay evaluates two different approaches to inferring expectations of future interest rates from asset prices. One is based on bond data and builds on the Black, Derman and Toy model, the other is based on option prices. We compare the outcome with a specified assumed benchmark data generating process. The main conclusion is that the option based model works well, whereas the bond based model has difficulties in capturing aspects of the true distribution."Natura non facit saltum – Or Are Jumps an Inherent Feature in European Interest Rate Markets?" A jump-enhanced diffusion model for the instantaneous interest rate is estimated on the EURIBOR, LIBOR and STIBOR one-week interest rates via the characteristic function and a Fourier transform to recover the density function. This is compared with an estimated non-jump diffusion model. Both continuous-time and discrete-time versions of the model are estimated. For all three interest rate series, likelihood ratio tests favor the jump-enhanced model at a statistically significant level. This result holds for both the continuous-time and the discrete-time versions of the model."Estimating the Market Price of Risk in European Interest Rate Markets Using Spectral GMM." The market price of risk in European interest rate markets, constituted by the market price of diffusion risk and the market price of jump risk, is estimated for a jump diffusion model, using the characteristic function and the Generalized Method of Moments. Utilized data is the EURIBOR twelve-month interest rate during 1999-2003. The results are in line with earlier studies on US interest rate markets. The estimation technique appears promising in its technical simplicity, but entails practical estimation difficulties such as start-value sensitivity and lack of efficiency.
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