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

Area of Science:

• Medical Mycology
• Microbiome Research
• Environmental Microbiology

Background:

• Commensal fungi like Malassezia, Candida, and Rhodotorula inhabit healthy skin but can cause infections.
• Previous skin microbiome studies primarily focused on bacteria (16S rRNA), with limited understanding of yeast diversity variations.
• Geographic, climatic, and ethnic factors are hypothesized to influence skin commensal yeast populations.

Purpose of the Study:

• To investigate the impact of geography, climate, and ethnicity on healthy skin commensal yeast diversity.
• To compare yeast communities between Singapore (tropical, multi-ethnic) and Zürich (temperate, Caucasian) populations.
• To validate the utility of culture-based methods for pathogenicity and antifungal susceptibility studies.

Main Methods:

• Identical skin sampling and culture-based methods were used for cohorts in Singapore and Zürich.
• Culture-dependent methods were employed, supplemented by sequence-based culture-independent methods.
• Multilocus sequence typing was utilized for strain characterization.

Main Results:

• Healthy skin yeast diversity reflects geographic, climatic, and ethnic influences.
• Tropical climates showed higher positive culture rates and greater yeast species diversity.
• Geographically distinct yeast strains were identified, potentially aiding in segregating pathogenic commensals.

Conclusions:

• Skin mycobiome composition is significantly influenced by extrinsic environmental factors.
• Culture-dependent and independent methods are recommended for comprehensive skin microbial community analysis.
• Characterizing healthy skin mycobiomes globally is crucial for understanding fungal roles in health and disease.