Culturable yeast diversity in urban topsoil influenced by various anthropogenic impacts.

In urban ecosystems, processes associated with anthropogenic influences almost always lead to changes in soil micromycete complexes. The taxonomic structure of soil micromycete complexes is an important informative parameter of soil bioindication in the ecological control of urban environments. Unicellular fungi, such as culturable yeasts, are a very suitable and promising object of microbiological research for monitoring urban topsoil. This review aims to give an overview of the yeast communities in urban topsoil in different areas of Moscow (heating main area, household waste storage and disposal area, highway area) and to discuss the changes in the taxonomic structure of culturable yeast complexes depending on the type and intensity of anthropogenic impact.

Changes in urban soil yeast communities after a reduction in household waste during the COVID-19 pandemic.

The soils of streets, urban parks and suburban areas were examined for yeasts in the summer of 2020 on the territory of the southern cities of Russia and the Republic of Crimea: Krasnodar, Maykop, Sochi and Simferopol. The results of this study are compared with the results of a previous study carried out in these cities in 2019. This study was conducted three months after the lockdown due to the COVID-19 pandemic, which led to a sustained decline in household waste deposition in these areas. The number of tourists visiting these southern cities decreased significantly, and the number of walkers and visitors to urban parks fell sharply. In 2020, after the decline of household waste loads, the yeast abundance was slightly but reliably higher than in 2019. A total of 30 yeast species were observed - 11 ascomycetes and 19 basidiomycetes. This was more than in 2019 and was caused by twice as many autochthonous basidiomycetous yeast species (natural core community), which were found in urban soils only after the reduction in household waste in the environment - Apiotrichum dulcitum, A. laibachii, Saitozyma podzolica Solicoccozyma terricola. And at the same time, the proportion of clinically significant (opportunistic) yeasts, Candida sake and Meyerozyma guilliermondii, was much lower in 2020 than in 2019. Thus, the observed changes in yeast communities in urban soils could be a short-time response of the microbial community to a reduction in household waste.

Fungemia due to rare opportunistic yeasts: data from a population-based surveillance in Spain.

Fungemia due to rare yeasts constitutes an emerging but poorly investigated condition. Data on risk factors, clinical features, therapy, and outcome of episodes of fungemia due to rare (non-Candida, non-Cryptococcus) yeasts were analyzed in a population-based surveillance program conducted in 29 Spanish hospitals between May 2010 and April 2011. Species identification (DNA sequencing) and antifungal susceptibility testing (EUCAST and CLSI methods) were centrally performed. Fourteen out of 767 episodes of fungemia (1.8%) were due to rare yeasts: Trichosporon asahii, Magnusiomyces capitatus (three cases each), Rhodotorula mucilaginosa, Wickerhamomyces anomalus (two cases each), and Pichia kudriavzevii, Cyberlindnera fabianii, Kodamaea ohmeri, and Lodderomyces elongisporus (one case each). Misidentification by local laboratories was observed in two isolates. Breakthrough fungemia occurred in two episodes due to M. capitatus MIC values for echinocandins were generally high (particularly for M. capitatus, T. asahii, and R. mucilaginosa isolates [≥2 mg/l]), whereas T. asahii isolates showed MICs ≥1 mg/l to amphotericin B. Patients with fungemia due to rare yeasts were more likely to have hematological malignancies (28.6% vs. 7.8%; P-value = .021), chronic lung disease (50.0% vs. 22.3%; P-value = .023), and prior immunosuppression (57.1% vs. 22.2%; P-value = .005) compared to those with candidemia. The rate of clinical failure (persistent fungemia and/or 30-day mortality) was 46.2% and did not significantly differ from that observed in episodes of candidemia. In conclusion, non-Candida, non-Cryptococcus yeasts are uncommon causes of fungemia, with immunosuppression and chronic lung disease as predisposing factors. Outcome does not appear to be worse than that of candidemia.

Incidence and anatomic localization of oral candidiasis in patients with AIDS hospitalized in a public hospital in Belo Horizonte, MG, Brazil

The objective of this study was to evaluate the incidence, anatomic localization and yeast species isolated from each clinical type of oral candidiasis. The clinical samples were obtained from 67 patients with AIDS with CD4 cell counts below 200 cells/mm³ and hospitalized in a public hospital (Eduardo de Menezes Hospital) in the city of Belo Horizonte, MG, Brazil. Yeasts were isolated using Chromagar® Candida. The results show that 50.7 percent of these patients had oral candidiasis. The pseudomembranous form was the most frequent clinical manifestation of oral candidiasis, followed by the erythematous and angular cheilite forms. The most common site of these clinical forms of oral candidiasis was the tongue. Candida albicans was the most common yeast species isolated from the lesions. However, other species were also found to be associated with these forms of oral candidiasis.