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- Grankvist, A., et al.
(författare)
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Comparative Genomics of Clinical Isolates of the Emerging Tick-Borne Pathogen Neoehrlichia mikurensis
- 2021
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Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- Tick-borne 'Neoehrlichia (N.) mikurensis' is the cause of neoehrlichiosis, an infectious vasculitis of humans. This strict intracellular pathogen is a member of the family Anaplasmataceae and has been unculturable until recently. The only available genetic data on this new pathogen are six partially sequenced housekeeping genes. The aim of this study was to advance the knowledge regarding 'N. mikurensis' genomic relatedness with other Anaplasmataceae members, intra-species genotypic variability and potential virulence factors explaining its tropism for vascular endothelium. Here, we present the de novo whole-genome sequences of three 'N. mikurensis' strains derived from Swedish patients diagnosed with neoehrlichiosis. The genomes were obtained by extraction of DNA from patient plasma, library preparation using 10x Chromium technology, and sequencing by Illumina Hiseq-4500. 'N. mikurensis' was found to have the next smallest genome of the Anaplasmataceae family (1.1 Mbp with 27% GC contents) consisting of 845 protein-coding genes, every third of which with unknown function. Comparative genomic analyses revealed that 'N. mikurensis' was more closely related to Ehrlichia chaffeensis than to Ehrlichia ruminantium, the opposite of what 16SrRNA sequence-based phylogenetic analyses determined. The genetic variability of the three whole-genome-sequenced 'N. mikurensis' strains was extremely low, between 0.14 and 0.22 parts per thousand, a variation that was associated with geographic origin. No protein-coding genes exclusively shared by N. mikurensis and E. ruminantium were identified to explain their common tropism for vascular endothelium.
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| 2. |
- Höper, Linnea, et al.
(författare)
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Vasculitis due to Candidatus Neoehrlichia mikurensis : a cohort study of 40 Swedish patients
- 2021
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Ingår i: Clinical Infectious Diseases. - : Oxford University Press. - 1058-4838 .- 1537-6591. ; 73:7, s. e2372-e2378
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Candidatus (Ca.) Neoehrlichia (N.) mikurensis is an emerging tick-borne pathogen of humans that is closely related to Ehrlichia and Anaplasma species. This strict intracellular bacterium escapes detection by routine microbiologic diagnostic methods such as blood culture leading to considerable under-diagnosis of the infectious disease it causes, neoehrlichiosis.METHODS: Here, we describe the vascular and thromboembolic events afflicting a series of 40 patients diagnosed with neoehrlichiosis in Sweden during a 10-year period (2009-2019).RESULTS: The majority of the patients (60%) developed vascular events ranging from repeated thrombophlebitis, deep vein thrombosis, pulmonary embolism, transitory ischemic attacks to arteritis. Younger age was a risk factor for vascular complications. In contrast, there was no difference in the incidence of vascular events between immunosuppressed and immunocompetent patients. However, there were qualitative differences such that deep vein thrombosis exclusively afflicted the immunosuppressed patients whereas arteritis was restricted to the immunocompetent ones. We also present the case histories of two patients who developed vasculitis mimicking polyarteritis nodosa and giant cell arteritis. Both were cured by doxycycline treatment.CONCLUSIONS: Ca. N. mikurensis infection should be considered in patients living in tick-endemic areas of Europe and northern Asia who present with atypical vascular and/or thromboembolic events. Early diagnosis and antibiotics targeting this emerging infectious agent can eradicate the infection and prevent the development of new vascular events.
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