Dataset Information

Geographical and Ethnic Differences Influence Culturable Commensal Yeast Diversity on Healthy Skin.

ABSTRACT: Commensal fungi such as Malassezia, Candida, and Rhodotorula are common on healthy skin but are also associated with opportunistic invasive and superficial infections. Skin microbial community characterization has been extensively performed worldwide, with a focus on the 16S bacterial community. These studies have focused on geographically distinct or targeted cohorts with variable reported species distributions of commensal yeast species. To determine the effects of extrinsic environmental factors such as geography, climate, and ethnicity on detected healthy skin commensal yeast diversity, we compared cohorts from Singapore and Zürich, Switzerland, representative of two geographically and climatically distinct regions comprising multi-ethnic (Chinese, Malay, Indian, Caucasian) and predominantly white Caucasian cohorts, respectively, using identical skin sampling and culture methods. We chose to use a culture-based approach as cultures isolated from patients are still required for studies of pathogenicity and antifungal susceptibility. Detection of yeast species by culture-dependent and independent sequencing-based methods suggest healthy skin diversity reflects a species distribution representative of the geography, climate and ethnic background of their local populations. Culture success and species diversity was also found to be dependent on climate, with warm tropical climates favoring high positive culture rates and greater species diversity. Multilocus sequence typing data suggests some strains are geographically distinct and may be used to segregate potential disease-causing commensals. For accurate collection and characterization of skin microbial communities, it remains recommended to employ a combination of culture-dependent and sequence-based culture-independent methods. Characterization of healthy mycobiomes in geographically distinct local populations will be useful in defining the role of commensal fungi in health and disease.

SUBMITTER: Leong C

PROVIDER: S-EPMC6736582 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Geographical and Ethnic Differences Influence Culturable Commensal Yeast Diversity on Healthy Skin.

Leong Cheryl C Schmid Bettina B Toi Min Jet MJ Wang Joyce J Irudayaswamy Antony Sagayaraj AS Goh Joleen Peh Zhen JPZ Bosshard Philipp P PP Glatz Martin M Dawson Thomas L TL

Frontiers in microbiology 20190827

Commensal fungi such as Malassezia, Candida, and Rhodotorula are common on healthy skin but are also associated with opportunistic invasive and superficial infections. Skin microbial community characterization has been extensively performed worldwide, with a focus on the 16S bacterial community. These studies have focused on geographically distinct or targeted cohorts with variable reported species distributions of commensal yeast species. To determine the effects of extrins ...[more]

PMID: 31551938

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Project description:UNLABELLED:Malassezia commensal yeasts are associated with a number of skin disorders, such as atopic eczema/dermatitis and dandruff, and they also can cause systemic infections. Here we describe the 7.67-Mbp genome of Malassezia sympodialis, a species associated with atopic eczema, and contrast its genome repertoire with that of Malassezia globosa, associated with dandruff, as well as those of other closely related fungi. Ninety percent of the predicted M. sympodialis protein coding genes were experimentally verified by mass spectrometry at the protein level. We identified a relatively limited number of genes related to lipid biosynthesis, and both species lack the fatty acid synthase gene, in line with the known requirement of these yeasts to assimilate lipids from the host. Malassezia species do not appear to have many cell wall-localized glycosylphosphatidylinositol (GPI) proteins and lack other cell wall proteins previously identified in other fungi. This is surprising given that in other fungi these proteins have been shown to mediate interactions (e.g., adhesion and biofilm formation) with the host. The genome revealed a complex evolutionary history for an allergen of unknown function, Mala s 7, shown to be encoded by a member of an amplified gene family of secreted proteins. Based on genetic and biochemical studies with the basidiomycete human fungal pathogen Cryptococcus neoformans, we characterized the allergen Mala s 6 as the cytoplasmic cyclophilin A. We further present evidence that M. sympodialis may have the capacity to undergo sexual reproduction and present a model for a pseudobipolar mating system that allows limited recombination between two linked MAT loci. IMPORTANCE:Malassezia commensal yeasts are associated with a number of skin disorders. The previously published genome of M. globosa provided some of the first insights into Malassezia biology and its involvement in dandruff. Here, we present the genome of M. sympodialis, frequently isolated from patients with atopic eczema and healthy individuals. We combined comparative genomics with sequencing and functional characterization of specific genes in a population of clinical isolates and in closely related model systems. Our analyses provide insights into the evolution of allergens related to atopic eczema and the evolutionary trajectory of the machinery for sexual reproduction and meiosis. We hypothesize that M. sympodialis may undergo sexual reproduction, which has important implications for the understanding of the life cycle and virulence potential of this medically important yeast. Our findings provide a foundation for the development of genetic and genomic tools to elucidate host-microbe interactions that occur on the skin and to identify potential therapeutic targets.

Project description:Next-generation sequencing (NGS) and metagenomics revolutionized our capacity for analysis and identification of the microbial communities in complex samples. The existence of a blood microbiome in healthy individuals has been confirmed by sequencing, but some researchers suspect that this is a cell-free circulating DNA in blood, while others have had isolated a limited number of bacterial and fungal species by culture. It is not clear what part of the blood microbiota could be resuscitated and cultured. Here, we quantitatively measured the culturable part of blood microbiota of healthy individuals by testing a medium supplemented with a high concentration of vitamin K (1 mg/mL) and culturing at 43 °C for 24 h. We applied targeted sequencing of 16S rDNA and internal transcribed spacer (ITS) markers on cultured and non-cultured blood samples from 28 healthy individuals. Dominant bacterial phyla among non-cultured samples were Proteobacteria 92.97%, Firmicutes 2.18%, Actinobacteria 1.74% and Planctomycetes 1.55%, while among cultured samples Proteobacteria were 47.83%, Firmicutes 25.85%, Actinobacteria 16.42%, Bacteroidetes 3.48%, Cyanobacteria 2.74%, and Fusobacteria 1.53%. Fungi phyla Basidiomycota, Ascomycota, and unidentified fungi were 65.08%, 17.72%, and 17.2% respectively among non-cultured samples, while among cultured samples they were 58.08%, 21.72%, and 20.2% respectively. In cultured and non-cultured samples we identified 241 OTUs belonging to 40 bacterial orders comprising 66 families and 105 genera. Fungal biodiversity accounted for 272 OTUs distributed in 61 orders, 105 families, and 133 genera. Bacterial orders that remained non-cultured, compared to blood microbiota isolated from fresh blood collection, were Sphingomonadales, Rhizobiales, and Rhodospirillales. Species of orders Bacillales, Lactobacillales, and Corynebacteriales showed the best cultivability. Fungi orders Tremellales, Polyporales, and Filobasidiales were mostly unculturable. Species of fungi orders Pleosporales, Saccharomycetales, and Helotiales were among the culturable ones. In this study, we quantified the capacity of a specific medium applied for culturing of blood microbiota in healthy individuals. Other culturing conditions and media should be tested for optimization and better characterization of blood microbiota in healthy and diseased individuals.

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Project description:BackgroundIn Ecuador eclampsia and preeclampsia were identified as the third cause of maternal death. Like other Latin-American countries, Ecuador has human settlements living from 0 to more than 4000 m of altitude and comprising a wide ethnic-diversity across all these altitude changes. These characteristics offer the possibility to study a wide variety of possible risk factors for preeclampsia and eclampsia.MethodsWe conducted a population-based retrospective study of all deliveries in Ecuador from 2015 through 2017. The main variables analyzed were: altitude, ethnic self-identification, geographic location, and maternal age. The data comes from the Ecuadorian National Institute of Statistics and Census (INEC) and the Ecuadorian Ministry of Health. Data information regarding maternal parity and socioeconomic status was not available from official records. Logistic regression analysis was used to study the relationship between preeclampsia and eclampsia with the variable of interest. Geospatial statistical analysis was done to identify statistically significant spatial clusters of preeclampsia and eclampsia cases.ResultsThe incidence of preeclampsia was estimated between 5.11 (5.05-5.18) and 6.23 (6.16-6.30), and 0.25 (0.23-0.26) for eclampsia. Native American have a lower incidence regarding preeclampsia compared to other ethnic groups. High altitude has a significant odds ratio (OR = 2.31, 1.93-2.78) of preeclampsia. Montubio residing in middle altitude (1500-3500 m) have the highest risk of preeclampsia (OR = 18.13, 9.53-34.50). Afro-Ecuadorians also have an increased risk of preeclampsia associated with altitude (OR = 2.36, 1.78-3.14). Ethnicity was not identified as a risk factor for eclampsia. Early and older maternal age was associated with an increased risk of preeclampsia and eclampsia. Women living more than 20 km from the obstetric unit have an OR = 2.61 (2.32-2.95, p-value< 0.01) and OR = 1.87 (1.82-1.92, p-value< 0.01) of developing eclampsia and preeclampsia respectively.ConclusionsPreeclampsia is widespread across low and high-altitude areas, while eclampsia is mostly located at lower altitudes. Montubios living at middle or high altitudes represents the ethnic group with a higher risk of preeclampsia. No ethnic effect was identified as a potential risk factor for eclampsia. Moreover, in eclampsia the associated risk of young women seems to be higher than in preeclampsia.

Dataset Information

Geographical and Ethnic Differences Influence Culturable Commensal Yeast Diversity on Healthy Skin.

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Geographical and Ethnic Differences Influence Culturable Commensal Yeast Diversity on Healthy Skin.

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