Environmental prospecting of black yeast-like agents of human disease using culture-independent methodology

Abstract

Melanized fungi and black yeasts in the family Herpotrichiellaceae (order chaetothyriales) are important agents of human and animal infectious diseases such as chromoblastomycosis and phaeohyphomycosis. the oligotrophic nature of these fungi enables them to survive in adverse environments where common saprobes are absent. Due to their slow growth, they lose competition with common saprobes, and therefore isolation studies yielded low frequencies of clinically relevant species in environmental habitats from which humans are thought to be infected. this problem can be solved with metagenomic techniques which allow recognition of microorganisms independent from culture. the present study aimed to identify species of the family Herpotrichiellaceae that are known to occur in Brazil by the use of molecular markers to screen public environmental metagenomic datasets from Brazil available in the Sequence Read Archive (SRA). Species characterization was performed with the BLASt comparison of previously described barcodes and padlock probe sequences. A total of 18,329 sequences was collected comprising the genera Cladophialophora, Exophiala, Fonsecaea, Rhinocladiella and Veronaea, with a focus on species related to the chromoblastomycosis. the data obtained in this study demonstrated presence of these opportunists in the investigated datasets. the used techniques contribute to our understanding of environmental occurrence and epidemiology of black fungi. A large number of species of black yeast-like fungi that belong to the ascomycetous order Chaetothyriales in the family Herpotrichiellaceae are renowned as opportunistic pathogens in immunocompetent vertebrate hosts 1,2. Agents are particularly involved in subcutaneous, and systemic or disseminated infections, known as chromoblastomycosis and phaeohyphomycosis, respectively 2-4. These infections are invariably chronic and can be severely mutilating or even fatal. Chromoblastomycosis is a relatively common disease in rural tropical climate zones around the world. This implantation disorder is characterized by the presence of a specialized tissue form of the fungus known as the muriform cell 2,5,6. Infection is hypothesized to take place via traumatic inoculation of environmental material such as plant thorns and/or wood fragments 7,8. Epidemiological data confirmed by studies using selective

Metagenomics reveals an abundance of black yeast‐like fungi in the skin microbiome

“…However, some groups have remained unexplored by conventional culture‐based methods. Our study systematically investigated in silico the presence of the Chaetothyriales sequences in metagenomic public datasets, using sequences of validated molecular markers following the methodologies proposed by Costa et al 25 …”

“…Chromoblastomycosis is a chronic, granulomatous mycosis of skin and subcutaneous tissue caused by the implantation of contaminated plant spines or wood fragments 19,21–23 . Epidemiological studies found that mycosis has an environmental origin 23–25 . Phaeohyphomycosis is a general term used to refer to opportunistic, cutaneous and systemic infections caused by melanized fungi involving immunocompromised and healthy individuals 26 .…”

“…19,[21][22][23] Epidemiological studies found that mycosis has an environmental origin. [23][24][25] Phaeohyphomycosis is a general term used to refer to opportunistic, cutaneous and systemic infections caused by melanized fungi involving immunocompromised and healthy individuals. 26 Cladophialophora bantiana and Rhinocladiella mackenziei are the most virulent species in the Chaetothyriales, causing fatal cerebral infections.…”

New possibilities for chromoblastomycosis and phaeohyphomycosis treatment: identification of two compounds from the MMV Pathogen Box® that present synergism with itraconazole

“…Many species of melanised filamentous fungi and black yeasts that belong to the Herpotrichiellaceae family are agents involved in subcutaneous, systemic or disseminated infections, known as chromoblastomycosis (CBM) or phaeohyphomycosis (PHM). 1 , 2 , 3 , 4 Some species of this family also cause eumycotic mycetoma. 5 …”

“…Many species of melanised filamentous fungi and black yeasts that belong to the Herpotrichiellaceae family are agents involved in subcutaneous, systemic or disseminated infections, known as chromoblastomycosis (CBM) or phaeohyphomycosis (PHM). (1,2,3,4) Some species of this family also cause eumycotic mycetoma. (5) CBM is an implantation neglected disease, caused by melanised fungi widely found in nature which infect mainly agricultural workers after transcutaneous inoculation, (2,6,7,8) thus constituting an occupational disease.…”