Evaluation of opportunistic yeasts Candida parapsilosis and Candida tropicalis in topsoil of children's playgrounds

Yeasts are an obligate component of the microbial communities of both undisturbed natural soils and disturbed soils in urban ecosystems. In urban environments changes occur in the yeast complexes in the soil that largely depend on the intensity of the prevailing anthropogenic influences. Yeasts in urban topsoil in playgrounds have been little studied so far. However, even these studies show that opportunistic and pathogenic species of the genera Candida and Cryptococcus can occur there. The presence of such yeasts can pose a serious threat to children whose immune system is not yet sufficiently developed and to adults whose immunity is weakened. We analysed the topsoil (0-15 cm) of ten playgrounds in the city of Moscow throughout the year for the presence of opportunistic and pathogenic Candida yeasts included in the "WHO fungal priority pathogens list" in 2022 (WHO FPPL). In addition, the susceptibility profile of the isolated strains to three conventional antifungal agents was evaluated: Fluconazole, Voriconazole and Amphotericin B. Two opportunistic Candida species, C. parapsilosis and C. tropicalis, were observed during the study period. Resistance to fluconazole was detected in 41% of C. parapsilosis strains and in 54% of C. tropicalis strains; resistance to voriconazole was detected in 18% of C. parapsilosis strains and in 12% of C. tropicalis strains, and the lowest percentage of resistant strains was detected to amphotericin B, namely 3% and 1% of C. parapsilosis and C. tropicalis strains, respectively. Thus, urban topsoil in playgrounds can be considered as a reservoir for the maintenance and spread of yeasts with potential health risks for children and adults.