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  • 1
    Online Resource
    Online Resource
    American Society for Microbiology ; 2017
    In:  mSphere Vol. 2, No. 1 ( 2017-02-22)
    In: mSphere, American Society for Microbiology, Vol. 2, No. 1 ( 2017-02-22)
    Abstract: Aspergillus fumigatus is a ubiquitous opportunistic fungal pathogen capable of causing invasive aspergillosis, a globally distributed disease with a mortality rate of up to 90% in high-risk populations. Effective control and prevention of this disease require a thorough understanding of its epidemiology. However, despite significant efforts, the global molecular epidemiology of A. fumigatus remains poorly understood. In this study, we analyzed 2,026 A. fumigatus isolates from 13 countries in four continents using nine highly polymorphic microsatellite markers. Genetic cluster analyses suggest that our global sample of A. fumigatus isolates belonged to eight genetic clusters, with seven of the eight clusters showing broad geographic distributions. We found common signatures of sexual recombination within individual genetic clusters and clear evidence of hybridization between several clusters. Limited but statistically significant genetic differentiations were found among geographic and ecological populations. However, there was abundant evidence for gene flow at the local, regional, and global scales. Interestingly, the triazole-susceptible and triazole-resistant populations showed different population structures, consistent with antifungal drug pressure playing a significant role in local adaptation. Our results suggest that global populations of A. fumigatus are shaped by historical differentiation, contemporary gene flow, sexual reproduction, and the localized antifungal drug selection that is driving clonal expansion of genotypes resistant to multiple triazole drugs. IMPORTANCE The genetic diversity and geographic structure of the human fungal pathogen A. fumigatus have been the subject of many studies. However, most previous studies had relatively limited sample ranges and sizes and/or used genetic markers with low-level polymorphisms. In this paper, we characterize a global collection of strains of A. fumigatus using a panel of 9 highly polymorphic microsatellite markers. Using these markers, we analyze 2,026 isolates, which is ~3 times the number of isolates reported so far in previous studies. Our analyses suggest that A. fumigatus contains historically differentiated genetic populations but that its evolution is significantly impacted by contemporary forces such as widespread gene flow and local antifungal drug pressure. In the wake of a global rise in resistance to azoles in fungal pathogens, our findings should aid in developing management strategies to mitigate current increases to azole resistance.
    Type of Medium: Online Resource
    ISSN: 2379-5042
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 2844248-9
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  • 2
    In: Canadian Journal of Microbiology, Canadian Science Publishing, Vol. 64, No. 2 ( 2018-02), p. 119-130
    Abstract: Aspergillus fumigatus is a ubiquitous opportunistic fungal pathogen that can cause aspergillosis in humans. Over the last decade there have been increasing global reports of treatment failure due to triazole resistance. An emerging hypothesis states that agricultural triazole fungicide use causes clinical triazole resistance. Here we test this hypothesis in Hamilton, Ontario, Canada, by examining a total of 195 agricultural, urban, and clinical isolates using 9 highly polymorphic microsatellite markers. For each isolate, the in vitro susceptibilities to itraconazole and voriconazole, 2 triazole drugs commonly used in the management of patients, were also determined. Our analyses suggested frequent gene flow among the agricultural, urban environmental, and clinical populations of A. fumigatus and found evidence for widespread sexual recombination within and among the different populations. Interestingly, all 195 isolates analyzed in this study were susceptible to both triazoles tested. However, compared with the urban population, agricultural and clinical populations showed significantly reduced susceptibility to itraconazole and voriconazole, consistent with ecological niche-specific selective pressures on A. fumigatus populations in Hamilton. Frequent gene flow and genetic recombination among these populations suggest greater attention should be paid to monitor A. fumigatus populations in Hamilton and other similar jurisdictions.
    Type of Medium: Online Resource
    ISSN: 0008-4166 , 1480-3275
    RVK:
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2018
    detail.hit.zdb_id: 280534-0
    detail.hit.zdb_id: 1481972-7
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Elsevier BV ; 2015
    In:  Infection, Genetics and Evolution Vol. 36 ( 2015-12), p. 199-209
    In: Infection, Genetics and Evolution, Elsevier BV, Vol. 36 ( 2015-12), p. 199-209
    Type of Medium: Online Resource
    ISSN: 1567-1348
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2015
    detail.hit.zdb_id: 2057622-5
    SSG: 12
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