Dematiaceous fungal pathogens isolated from nature

Area of Science:

• Mycology
• Environmental Microbiology

Background:

• Dematiaceous fungi are a group of fungi characterized by dark-colored cell walls.
• Some species are known human pathogens, but their prevalence in natural environments requires further investigation.

Purpose of the Study:

• To identify and characterize pathogenic dematiaceous fungi present in natural environments.
• To assess the pathogenicity of environmental isolates in laboratory animals.

Main Methods:

• Samples of woody plant material and soil were collected from Virginia.
• Fungal isolates were obtained through inoculation of hamsters and mice.
• Species identification was performed using morphological characteristics and biochemical tests.

Main Results:

• Forty-three isolates of dematiaceous fungi were recovered from 39 environmental samples.
• Thirteen species were identified, including Phialophora spp., Cladosporium spp., Exophiala spp., Sporothrix sp., Wangiella dermatitidis, Bispora betulina, and Scytalidium lignicola.
• Cladosporium trichoides was isolated from nature in the U.S. for the first time and demonstrated pathogenicity in mice.

Conclusions:

• Pathogenic dematiaceous fungi are present in natural environments in Virginia.
• Environmental isolates of Phialophora verrucosa, Phialophora repens, Exophiala jeanselmei, and Wangiella dermatitidis are morphologically and biochemically similar to human clinical isolates.
• This study highlights the ecological presence of fungi with potential human health implications.