Pathogenic budding yeasts isolated outside of clinical settings

Area of Science:

• Mycology
• Environmental Microbiology
• Human Health

Background:

• Budding yeasts are common human commensals but can cause opportunistic infections.
• The environmental ecology of pathogenic yeasts is poorly understood, limiting knowledge of infection origins.
• Current knowledge primarily links pathogenic yeasts to mammals and clinical settings.

Purpose of the Study:

• To investigate the non-clinical ecological distribution of pathogenic budding yeasts in the USA.
• To identify potential environmental reservoirs for opportunistic yeast pathogens.
• To understand the ecological niches of key species causing candidiasis.

Main Methods:

• Survey of approximately 1000 non-clinical environmental samples across the USA.
• Isolation and identification of budding yeast strains, including common opportunistic pathogens.
• Statistical analysis to determine associations between yeast species and environmental sources.

Main Results:

• 54 strains of pathogenic budding yeasts were isolated, including Candida albicans and Candida (Nakaseomyces) glabrata.
• Pathogenic yeasts as a group showed positive associations with fruits and soil.
• Pichia kudriavzevii (syn. Candida krusei) was significantly associated with plants.
• The four main species causing candidiasis were positively associated with soil environments.

Conclusions:

• The ecology of pathogenic yeasts is more diverse than previously recognized.
• Fruits, soil, and plants represent potential environmental reservoirs for opportunistic pathogenic yeasts.
• These environments may serve as previously unrecognized sources for human infections, highlighting the need for further ecological research.