Evidence of unique genetic diversity in <i>Aspergillus fumigatus</i> isolates from Cameroon

Ashu, Eta Ebasi; Korfanty, Gregory A.; Xu, Jianping

doi:10.1111/myc.12655

Cited by 19 publications

(31 citation statements)

References 35 publications

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“…The statistical significance of yeast isolation rate differences and of species diversity differences between the locations were determined using a Chi-square test against the null hypothesis that there was no difference between different locations/regions. A Pearson correlation test was preformed between the isolation rate of yeasts obtained in this study and the isolation rate of Aspergillus fumigatus in the same locations 21 using Excel (software XLSTAT 365, 2017).…”

Section: Methodsmentioning

confidence: 99%

Diversity and relationships among strains of culturable yeasts in agricultural soils in Cameroon

Aljohani

Samarasinghe

Ashu

et al. 2018

Sci Rep

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Yeasts are unicellular fungi; they are found in a diverse range of natural habitats, including soil, aquatic environments, the surface of plants, and the skin and mucosal surfaces of animal hosts. A variety of yeasts have been found in the soil environment. However, most studies of soil yeasts have come from developed countries, and there is a dearth of research on soil yeasts in Africa. In this study, we analyzed 493 soil samples from nine geographical locations in Cameroon for yeasts, using a culture - based method. A total of 110 yeast isolates were obtained. Based on their sequences at the fungal barcode locus, the Internal Transcribed Spacer (ITS) regions of the nuclear ribosomal RNA gene cluster, the 110 yeast isolates were putatively identified as belonging to 16 yeast species, including 15 Ascomycetes and one Basidiomycete. Differences in yeast species distribution were observed among the analyzed geographic regions. PCR fingerprinting analyses identified a large number of genotypes among strains within each of the obtained yeast species. Significantly, there was little evidence of geographic clustering among yeast strains from any of the yeast species. Our results suggest that Cameroon contains significant yeast diversity and that gene flow is common among local and regional soil yeast populations.

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Section: Methodsmentioning

confidence: 99%

Diversity and relationships among strains of culturable yeasts in agricultural soils in Cameroon

Aljohani

Samarasinghe

Ashu

et al. 2018

Sci Rep

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“…Compared to the large global population of Aspergilli , relatively few isolates and genotypes have been analyzed to date, and our current understanding of the molecular variation between and within these populations may not be representative of the true global diversity. In regard to tracking Aspergilli , geographic sub-structuring can vary by country and region, hence tracking transmission patterns of clinically relevant Aspergilli within or between certain countries might prove to be easier than in others [ 39 , 66 ]. For example, little to no geographic population structuring has been reported in A. fumigatus samples from India and Netherlands, whereas Cameroonian A. fumigatus samples show significant evidence for geographic sub-structuring [ 66 ].…”

Section: Molecular Epidemiology In Aspergillus mentioning

confidence: 99%

“…In regard to tracking Aspergilli , geographic sub-structuring can vary by country and region, hence tracking transmission patterns of clinically relevant Aspergilli within or between certain countries might prove to be easier than in others [ 39 , 66 ]. For example, little to no geographic population structuring has been reported in A. fumigatus samples from India and Netherlands, whereas Cameroonian A. fumigatus samples show significant evidence for geographic sub-structuring [ 66 ]. As a result, tracking clinically relevant A. fumigatus strains would be a more feasible task in Cameroon than it would be in India or Netherlands.…”

Section: Molecular Epidemiology In Aspergillus mentioning

confidence: 99%

Strengthening the One Health Agenda: The Role of Molecular Epidemiology in Aspergillus Threat Management

Ashu

2018

Genes

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The United Nations’ One Health initiative advocates the collaboration of multiple sectors within the global and local health authorities toward the goal of better public health management outcomes. The emerging global health threat posed by Aspergillus species is an example of a management challenge that would benefit from the One Health approach. In this paper, we explore the potential role of molecular epidemiology in Aspergillus threat management and strengthening of the One Health initiative. Effective management of Aspergillus at a public health level requires the development of rapid and accurate diagnostic tools to not only identify the infecting pathogen to species level, but also to the level of individual genotype, including drug susceptibility patterns. While a variety of molecular methods have been developed for Aspergillus diagnosis, their use at below-species level in clinical settings has been very limited, especially in resource-poor countries and regions. Here we provide a framework for Aspergillus threat management and describe how molecular epidemiology and experimental evolution methods could be used for predicting resistance through drug exposure. Our analyses highlight the need for standardization of loci and methods used for molecular diagnostics, and surveillance across Aspergillus species and geographic regions. Such standardization will enable comparisons at national and global levels and through the One Health approach, strengthen Aspergillus threat management efforts.

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“…Multiple studies conducted in the past 30 years have used a range of molecular markers to help unravel the population genetics of A. fumigatus (14, 26–31). Findings have ranged from no genetic structure to multiple distinct clusters, with varying reproducibility being found across methodologies.…”

Section: Introductionmentioning

confidence: 99%

Nonrandom Distribution of Azole Resistance across the Global Population of Aspergillus fumigatus

Sewell

Zhu

Rhodes

et al. 2019

mBio

107

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The emergence of azole resistance in the pathogenic fungus Aspergillus fumigatus has continued to increase, with the dominant resistance mechanisms, consisting of a 34-nucleotide tandem repeat (TR34)/L98H and TR46/Y121F/T289A, now showing a structured global distribution. Using hierarchical clustering and multivariate analysis of 4,049 A. fumigatus isolates collected worldwide and genotyped at nine microsatellite loci using analysis of short tandem repeats of A. fumigatus (STRAf), we show that A. fumigatus can be subdivided into two broad clades and that cyp51A alleles TR34/L98H and TR46/Y121F/T289A are unevenly distributed across these two populations. Diversity indices show that azole-resistant isolates are genetically depauperate compared to their wild-type counterparts, compatible with selective sweeps accompanying the selection of beneficial mutations. Strikingly, we found that azole-resistant clones with identical microsatellite profiles were globally distributed and sourced from both clinical and environmental locations, confirming that azole resistance is an international public health concern. Our work provides a framework for the analysis of A. fumigatus isolates based on their microsatellite profile, which we have incorporated into a freely available, user-friendly R Shiny application (AfumID) that provides clinicians and researchers with a method for the fast, automated characterization of A. fumigatus genetic relatedness. Our study highlights the effect that azole drug resistance is having on the genetic diversity of A. fumigatus and emphasizes its global importance upon this medically important pathogenic fungus. IMPORTANCE Azole drug resistance in the human-pathogenic fungus Aspergillus fumigatus continues to emerge, potentially leading to untreatable aspergillosis in immunosuppressed hosts. Two dominant, environmentally associated resistance mechanisms, which are thought to have evolved through selection by the agricultural application of azole fungicides, are now distributed globally. Understanding the effect that azole resistance is having on the genetic diversity and global population of A. fumigatus will help mitigate drug-resistant aspergillosis and maintain the azole class of fungicides for future use in both medicine and crop protection.

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Evidence of unique genetic diversity in Aspergillus fumigatus isolates from Cameroon

Cited by 19 publications

References 35 publications

Diversity and relationships among strains of culturable yeasts in agricultural soils in Cameroon

Diversity and relationships among strains of culturable yeasts in agricultural soils in Cameroon

Strengthening the One Health Agenda: The Role of Molecular Epidemiology in Aspergillus Threat Management

Nonrandom Distribution of Azole Resistance across the Global Population of Aspergillus fumigatus

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