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- Berglund, Eva C., et al.
(author)
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Genome dynamics of Bartonella grahamii in micro-populations of woodland rodents
- 2010
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In: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 11, s. 152-
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Journal article (peer-reviewed)abstract
- Background: Rodents represent a high-risk reservoir for the emergence of new human pathogens. The recent completion of the 2.3 Mb genome of Bartonella grahamii, one of the most prevalent blood-borne bacteria in wild rodents, revealed a higher abundance of genes for host-cell interaction systems than in the genomes of closely related human pathogens. The sequence variability within the global B. grahamii population was recently investigated by multi locus sequence typing, but no study on the variability of putative host-cell interaction systems has been performed. Results: To study the population dynamics of B. grahamii, we analyzed the genomic diversity on a whole-genome scale of 27 B. grahamii strains isolated from four different species of wild rodents in three geographic locations separated by less than 30 km. Even using highly variable spacer regions, only 3 sequence types were identified. This low sequence diversity contrasted with a high variability in genome content. Microarray comparative genome hybridizations identified genes for outer surface proteins, including a repeated region containing the fha gene for filamentous hemaggluttinin and a plasmid that encodes a type IV secretion system, as the most variable. The estimated generation times in liquid culture medium for a subset of strains ranged from 5 to 22 hours, but did not correlate with sequence type or presence/absence patterns of the fha gene or the plasmid. Conclusion: Our study has revealed a geographic microstructure of B. grahamii in wild rodents. Despite near-identity in nucleotide sequence, major differences were observed in gene presence/absence patterns that did not segregate with host species. This suggests that genetically similar strains can infect a range of different hosts.
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| 3. |
- Ehrenborg, Christian, 1970-
(author)
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Bartonella Infections in Sweden: : Clinical Investigations and Molecular Epidemiology
- 2007
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Doctoral thesis (other academic/artistic)abstract
- Characteristically, in infections that are caused by the zoonotic pathogen Bartonella naturally infected reservoir hosts are asymptomatic, where infected incidental, non-natural, hosts develop symptomatic disease. Cat-scratch disease (CSD) is a well known example. Bartonella infections in humans may be self-limiting or fulminant and affect different organ systems. The objectives of the present thesis were to (1) identify and characterise Bartonella infection cases in Sweden, (2) to investigate certain human populations regarding Bartonella infections, and (3) compare natural populations of different Bartonella species. Cases with typical and atypical CSD were recognised by using a combination of PCR and serology. Gene sequence comparisons of different genes in B. henselae isolates from the United States and Europe showed that ftsZ gene variation is a useful tool for Bartonella genotyping. Myocarditis was a common finding among Swedish elite orienteers succumbing to sudden unexpected cardiac death (SUCD). The natural cycle of Bartonella spp., the life style of orienteers, elevated antibody titres to Bartonella antigens, Bartonella DNA amplified from myocardium and the lack of another feasible explanation make Bartonella a plausible aetiological factor. The first reported case of Bartonella endocarditis (B. quintana) was identified in an immunocompromised patient who underwent heart valve replacement. The patient had been body louse-infested during his childhood. It is hypothesised that a chronic B. quintana infection was activated by the immunosuppression. There was no evidence of an ongoing trench fever (TF) epidemic in a Swedish homeless population, although an increased risk for exposure to Bartonella antigens was demonstrated. The lack of louse infestation might explain the absence of B. quintana bacteremia and low B. quintana antibody titres. Comparisons of genetic loci and the whole genomes of environmental B. grahamii isolates from the Uppsala region, Sweden displayed variants that were not related to specific host species but to geographic locality. Natural boundaries seemed to restrict gene flow.
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| 5. |
- Ehrenborg, Christian, et al.
(author)
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First known case of Bartonella quintana endocarditis in Sweden
- 2009
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In: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 41:1, s. 73-75
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Journal article (peer-reviewed)abstract
- In this report, we present the first known case of Bartonella endocarditis in Sweden. IgG antibody titres to Bartonella spp. were elevated but blood cultures remained negative. Sequencing of a gltA fragment from DNA extracted from heart valve tissue specimens revealed sequence homology with B. quintana.
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| 6. |
- Ehrenborg, Christian, et al.
(author)
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High Bartonella spp. seroprevalence in a Swedish homeless population but no evidence of trench fever
- 2008
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In: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 40:3, s. 208-215
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Journal article (peer-reviewed)abstract
- Blood samples and epidemiological data were collected from 50 homeless patients in central Stockholm, Sweden. Sera were analysed for antibodies to B. henselae, B. quintana, B. elizabethae and B. grahamii. Whole blood was cultured and used as substrate for a newly developed quantitative real time polymerase chain reaction (QPCR) specifically targeting Bartonella spp. DNA. 61 matched blood donor sera were used as controls. Homeless patients were significantly more often seropositive to Bartonella spp. than controls (OR 7.58 (3.30-17.39), p<0.05). Reactivity to the B. elizabethae antigen was dominating, although the difference between patients and controls was most significant in seroreactivity to the B. henselae antigen. There was no evidence of an ongoing B. quintana epidemic. The absence of louse infestation could explain the lack of B. quintana bacteraemia and the failure to amplify Bartonella DNA.
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| 8. |
- Hagman, Karl, et al.
(author)
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On the potential roles of ticks and migrating birds in the ecology of West Nile virus
- 2014
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In: Infection Ecology & Epidemiology. - : Informa UK Limited. - 2000-8686. ; 4
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Journal article (peer-reviewed)abstract
- BACKGROUND: Mosquitoes are the primary vectors of West Nile virus (WNV). Ticks have, however, been suggested to be potential reservoirs of WNV. In order to investigate their role in the spread of the virus, ticks, which had been collected from birds migrating northwards from Africa to Europe, were analyzed for the potential presence of WNV-RNA.METHODS: On the Mediterranean islands Capri and Antikythira a total of 14,824 birds were captured and investigated from which 747 ticks were collected.RESULTS AND CONCLUSION: Most of the identified ticks (93%) were nymphs and larvae of Hyalomma marginatum sensu lato, most of which were or appear to be Hyalomma rufipes. Of these ticks 729 were individually screened for WNV-RNA. None of the ticks was found to be WNV positive. Thus, there was no evidence that Hyalomma marginatum s.l. ticks play a role in the spread of WNV from Africa to Europe.
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| 9. |
- Haris, Kostas, et al.
(author)
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Free-breathing fetal cardiac MRI with doppler ultrasound gating, compressed sensing, and motion compensation
- 2020
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In: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 51:1, s. 260-272
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Journal article (peer-reviewed)abstract
- BACKGROUND: Fetal cardiovascular MRI complements ultrasound to assess fetal cardiovascular pathophysiology.PURPOSE: To develop a free-breathing method for retrospective fetal cine MRI using Doppler ultrasound (DUS) cardiac gating and tiny golden angle radial sampling (tyGRASP) for accelerated acquisition capable of detecting fetal movements for motion compensation.STUDY TYPE: Feasibility study.SUBJECTS: Nine volunteers (gestational week 34-40). Short-axis and four-chamber views were acquired during maternal free-breathing and breath-hold.FIELD STRENGTH/SEQUENCE: 1.5T cine balanced steady-state free precession.ASSESSMENT: A self-gated reconstruction method was improved for clinical application by using 1) retrospective DUS gating, and 2) motion detection and rejection/correction algorithms for compensating for fetal motion. The free-breathing reconstructions were qualitatively and quantitatively assessed, and DUS-gating was compared with self-gating in breath-hold reconstructions. A scoring of 1-4 for overall image quality, cardiac, and extracardiac diagnostic quality was used.STATISTICAL TESTS: Friedman's test was used to assess differences in qualitative scoring between observers. A Wilcoxon matched-pairs signed rank test was used to assess differences between breath-hold and free-breathing acquisitions and between observers' quantitative measurements.RESULTS: In all cases, 111 free-breathing and 145 breath-hold acquisitions, the automatically calculated DUS-based cardiac gating signal provided reconstructions of diagnostic quality (median score 4, range 1-4). Free-breathing did not affect the DUS-based cardiac gated retrospective radial reconstruction with respect to image or diagnostic quality (all P > 0.06). Motion detection with rejection/correction in k-space produced high-quality free-breathing DUS-based reconstructions [median 3, range (2-4)], whereas free-breathing self-gated methods failed in 80 out of 88 cases to produce a stable gating signal.DATA CONCLUSION: Free-breathing fetal cine cardiac MRI based on DUS gating and tyGRASP with motion compensation yields diagnostic images. This simplifies acquisition for the pregnant woman and thus could help increase fetal cardiac MRI acceptance in the clinic.LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019.
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| 10. |
- Holmberg, Martin, et al.
(author)
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Evaluation of human seroreactivity to Bartonella species in Sweden
- 1999
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In: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 37:5, s. 1381-1384
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Journal article (peer-reviewed)abstract
- Among the species that compose the expanding genus Bartonella, thus far only B. henselae and B. quintana have reportedly been isolated from humans in Europe. To evaluate the prevalence of Bartonella infection in Sweden,we conducted a retrospective serological examination of 126 human serum samples. These samples were analyzed for antibodies to B. henselae, B. quintana, and B. elizabethae, Serum samples from 100 blood donors, who spanned the ages of 20 to 60 and had no apparent clinical signs of illness, were also studied as a control group. An immunoglobulin G indirect fluorescence antibody assay revealed 4 and 8.3% Bartonella positivity rates for the blood donor and patient group, respectively, when a cutoff titer of greater than or equal to 64 was chosen. Among the blood donors, four were seropositive to B, elizabethae; one of these also had concordant positive titer to B. henselae, In the patient group, 14 serum samples were positive against Bartonella spp, These serum specimens represented nine patients. In three of these seropositive patients, paired serum samples displayed a fourfold increase in antibody titer to at least one of the three antigens, These three patients are discussed. In this report we also present a case study of a 60-year-old Swedish male with fatal myocarditis, Postmortem serological analysis revealed a high titer against B. elizabethae, PCR and nucleotide sequencing of the myocardial tissue from this patient, and of Liver tissue from one of the other three patients, showed sequences similar to B. quintana, The age, geographical origin, animal contacts, and serological response pattern to the different Bartonella antigens differed among the four patients. This study substantiates the presence of Bartonella spp, in Sweden, documents the seroreactivity to three Bartonella antigens in Swedish patients, and reports the first two cases of B. quintana-like infections in Sweden.
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