The human opportunistic fungal pathogen Candida tropicalis is widely distributed in natural environments. In recent decades, the prevalence of azole-resistant isolates has increased markedly in the Asia-Pacific and Latin America. This epidemiological change could be associated with the extensive application of azole fungicides in modern agriculture. In this study, we demonstrate that exposure to four widely used agricultural azoles (difenoconazole, diniconazole, flutriafol, and hexaconazole) induces cross-resistance to medical azoles in an initially susceptible C. tropicalis strain. The evolved azole-resistant strains exhibited altered cellular and colony morphologies, along with changes in growth rates. Genomic analyses revealed that all evolved strains were aneuploid, with either partial chromosomal segment amplifications or extra chromosomes. Global transcriptomic analysis showed that many azole resistance-associated genes located within these amplified regions were upregulated, potentially contributing to resistance against both clinical and agricultural azoles. These findings highlight the potential role of agricultural azoles as the environmental drivers of antifungal resistance in the medically important fungal pathogen C. tropicalis, underscoring the importance of a One Health approach to antifungal stewardship.

The cactophilic yeasts, Sporopachydermia species, are intrinsic resistance to echinocandins. We report the first case of fungemia caused by S. lactativora in China. Sporopachydermia lactativora could colonise and infect multiple animal tissues and could represent a new emerging fungal pathogen of humans and should not be ignored in clinical settings.

Candida albicans is able to switch between two epigenetic cell types, namely white and opaque. Multiple conserved signalling pathways control the switch between white and opaque cell types in response to environmental changes. Here, we report the regulatory roles of the endosomal Rab family GTPase Vps21 and associated key components of the Vps21 signalling pathway in whiteopaque switching and mating in C. albicans. Deletion of VPS21 promoted a switch from the white to the opaque phenotype in the presence of N-acetyl-glucosamine (GlcNAc). Consistently, inactivation of the guanine nucleotide exchange factor of Vps21 (Vps9) and downstream components in the Vps21 pathway (Vps3, Vac1, and Pep12) had similar promoting effects on phenotypic switching. The mating efficiency of opaque cells is much higher than that of white cells under standard laboratory culture conditions. However, compared to the wildtype strain, the vps21/vps21, vps9/ vps9, vps3/vps3, vac1/vac1, and pep12/pep12 mutant strains exhibited dramatically reduced mating efficiencies. Quantitative RT-PCR assays demonstrated that inactivation of the Vps21 signalling pathway led to downregulation of pheromone expression and mating response pathway associated genes. Taken together, our findings indicate that the conserved Vps21 signalling pathway plays critical roles in the regulation of cell-type switching and mating in C. albicans.

The recently emerged fungal pathogen Candida auris often displays resistance to one or more antifungal drugs. Its infections have been identified in at least 40 countries on six continents to date. Here we report a case of C. auris candidemia in a patient in Xiamen, a city in south China. We also review currently reported cases of C. auris infection in China and compare the genetic and biological features of C. auris strains isolated from this country. Our phylogenetic analysis indicates that there are at least two C. auris genetic clades present in China (the South African clade and the south Asian clade) that display opposite mating type loci (one is MTLa and the other is MTLα). We also found that there are several distinct features among the clinical isolates studied, including the expression of virulence factors, antifungal susceptibilities, and cellular morphologies, and that these features could be associated with the mating-type of the isolate. For example, C. auris MTLa isolates generally secreted higher levels of secreted aspartyl proteases (Saps) at ambient environmental temperatures. Taken together, this study demonstrates that C. auris clinical isolates from China exhibit diversity in both biological and genetic features.