Dataset Information

Molecular Epidemiology of Blastomyces gilchristii Clusters, Minnesota, USA.

ABSTRACT: We characterized 2 clusters of blastomycosis cases in Minnesota, USA, using whole-genome sequencing and single-nucleotide polymorphism analyses. Blastomyces gilchristii was confirmed as the cause of infection. Genomic analyses corresponded with epidemiologic findings for cases of B. gilchristii infections, demonstrating the utility of genomic methods for future blastomycosis outbreak investigations.

SUBMITTER: Bagal UR

PROVIDER: S-EPMC9423935 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature

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Molecular Epidemiology of Blastomyces gilchristii Clusters, Minnesota, USA.

Bagal Ujwal R UR Ireland Malia M Gross Annastasia A Fischer Jill J Bentz Meghan M Berkow Elizabeth L EL Litvintseva Anastasia P AP Chow Nancy A NA

Emerging infectious diseases 20220901 9

We characterized 2 clusters of blastomycosis cases in Minnesota, USA, using whole-genome sequencing and single-nucleotide polymorphism analyses. Blastomyces gilchristii was confirmed as the cause of infection. Genomic analyses corresponded with epidemiologic findings for cases of B. gilchristii infections, demonstrating the utility of genomic methods for future blastomycosis outbreak investigations. ...[more]

PMID: 35997504

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Project description:Analysis of the population genetic structure of microbial species is of fundamental importance to many scientific disciplines because it can identify cryptic species, reveal reproductive mode, and elucidate processes that contribute to pathogen evolution. Here, we examined the population genetic structure and geographic differentiation of the sexual, dimorphic fungus Blastomyces dermatitidis, the causative agent of blastomycosis.Criteria for Genealogical Concordance Phylogenetic Species Recognition (GCPSR) applied to seven nuclear loci (arf6, chs2, drk1, fads, pyrF, tub1, and its-2) from 78 clinical and environmental isolates identified two previously unrecognized phylogenetic species. Four of seven single gene phylogenies examined (chs2, drk1, pyrF, and its-2) supported the separation of Phylogenetic Species 1 (PS1) and Phylogenetic Species 2 (PS2) which were also well differentiated in the concatenated chs2-drk1-fads-pyrF-tub1-arf6-its2 genealogy with all isolates falling into one of two evolutionarily independent lineages. Phylogenetic species were genetically distinct with interspecific divergence 4-fold greater than intraspecific divergence and a high Fst value (0.772, P<0.001) indicative of restricted gene flow between PS1 and PS2. Whereas panmixia expected of a single freely recombining population was not observed, recombination was detected when PS1 and PS2 were assessed separately, suggesting reproductive isolation. Random mating among PS1 isolates, which were distributed across North America, was only detected after partitioning isolates into six geographic regions. The PS2 population, found predominantly in the hyper-endemic regions of northwestern Ontario, Wisconsin, and Minnesota, contained a substantial clonal component with random mating detected only among unique genotypes in the population.These analyses provide evidence for a genetically divergent clade within Blastomyces dermatitidis, which we use to describe a novel species, Blastomyces gilchristii sp. nov. In addition, we discuss the value of population genetic and phylogenetic analyses as a foundation for disease surveillance, understanding pathogen evolution, and discerning phenotypic differences between phylogenetic species.

Project description:Blastomyces dermatitidis and Blastomyces gilchristii are dimorphic fungal pathogens that cause serious pulmonary and systemic infections in humans. Although their natural habitat is in the environment, little is known about their specific ecologic niche(s). Here, we analyzed 25 microsatellite loci from 169 strains collected from various regions throughout their known endemic range in North America, representing the largest and most geographically diverse collection of isolates studied to date. Genetic analysis of multilocus microsatellite data divided the strains into four populations of B. dermatitidis and four populations of B. gilchristii. B. dermatitidis isolates were recovered from areas throughout North America, while the B. gilchristii strains were restricted to Canada and some northern US states. Furthermore, the populations of both species were associated with major freshwater drainage basins. The four B. dermatitidis populations were partitioned among (1) the Nelson River drainage basin, (2) the St. Lawrence River and northeast Atlantic Ocean Seaboard drainage basins, (3) the Mississippi River System drainage basin, and (4) the Gulf of Mexico Seaboard and southeast Atlantic Ocean Seaboard drainage basins. A similar partitioning of the B. gilchristii populations was observed among the more northerly drainage basins only. These associations suggest that the ecologic niche where the sexual reproduction, growth, and dispersal of B. dermatitidis and B. gilchristii occur is intimately linked to freshwater systems. For most populations, sexual reproduction was rare enough to produce significant linkage disequilibrium among loci but frequent enough that mating-type idiomorphic ratios were not skewed from 1:1. Furthermore, the evolutionary divergence of B. dermatitidis and B. gilchristii was estimated at 1.9 MYA during the Pleistocene epoch. We suggest that repeated glaciations during the Pleistocene period and resulting biotic refugia may have provided the impetus for speciation as theorized for other species associated with temperate freshwater systems.

Project description:BackgroundAdrenal tumours are commonly encountered in clinical practice, but epidemiological data mainly originate from referral centres. We aimed to determine incidence, prevalence, and rates of malignancy and hormone excess in patients with adrenal tumours in a standardised geographically well defined population.MethodsIn this retrospective population-based cohort study we assessed the standardised incidence rate of adrenal tumours in all patients with tumours who lived in Olmsted County, MN, USA, from Jan 1, 1995, to Dec 31, 2017. The Rochester Epidemiology Project infrastructure, which links medical records across all health-care providers for the entire population of Olmsted County since 1966, was used to allow researchers to identify individuals with specific diagnoses, surgical interventions, and other procedures, and to locate their medical records, which were then used in the analysis. Incidence rates and prevalence were standardised for age and sex according to the 2010 US Population.FindingsAn adrenal tumour was diagnosed in 1287 patients (median age 62 years; 713 (55·4%) were women; and 13 (1·0%) were children). Standardised incidence rates increased from 4·4 (95% CI 0·3-8·6) per 100 000 person-years in 1995 to 47·8 (36·9-58·7) in 2017, mainly because of the incidental discovery of adenomas less than 40 mm in diameter in patients older than 40 years. Prevalence of adrenal tumours in 2017 was 532 per 100 000 inhabitants, ranging from 13 per 100 000 in children (aged <18 years) to 1900 per 100 000 in patients older than 65 years. 111 (8·6%) of 1287 patients were diagnosed with malignancy (96 [7·5%] of whom has metastases), 14 (1·1%) with phaeochromocytoma, and 53 (4·1%) with overt steroid hormone excess. Malignancy was more common in children (62%) versus those older than 18 years (8%; p<0·0001), tumours discovered during cancer-staging or follow-up (43% vs 3% for incidentalomas; p<0·0001), tumours more than 40 mm in diameter (34% vs 6% for tumours <20 mm; p<0·0001), tumours with unenhanced CT attenuation of 30 Hounsfield units or more (20% vs 1% for <20 Hounsfield units; p<·0001), and bilateral masses (16% vs 7% for unilateral, p=0·0004).InterpretationAdrenal tumour standardised incidence rates increased 10 times from 1995 to 2017. Population-based data revealed lower rates of malignancy, phaeochromocytoma, and overt steroid hormone excess than previously reported.FundingNational Institutes of Health.

Dataset Information

Molecular Epidemiology of Blastomyces gilchristii Clusters, Minnesota, USA.

Publications

Molecular Epidemiology of Blastomyces gilchristii Clusters, Minnesota, USA.

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