Análises taxogenômicas e perfil de virulência de espécies do gênero Candidozyma isoladas de biomas brasileiros

Abstract

In recent years, the number of infections caused by emerging fungi has increased significantly, partly due to global warming, which allows these organisms to adapt to higher temperatures. Within this context, the Candidozyma haemuli-auris complex has gained prominence due to its thermotolerance, resistance to antifungals, and potential to cause human infections. However, there is a gap in knowledge about environmental isolates of these species, which reinforces the need for detailed investigations of their ecological characteristics, susceptibility to antifungals, and virulence factors. The main objective of this study was to analyze the resistance to antifungals and virulence factors of isolates of the Candidozyma haemuli-auris complex, originating from various substrates in Brazilian biomes, in order to understand how these factors may be related to their environmental adaptation and pathogenic potential. The isolates were obtained from the Fungi and Cells Collection of UFMG, and these had been isolated from niches such as flowers, soil, and decaying wood, representing biomes such as the Amazon and Cerrado. From these isolates, species identification studies were performed using molecular sequencing, antifungal susceptibility tests, virulence tests, such as thermotolerance, biofilm, efflux pump, cell adhesion, filamentation induction and genomic analyses. Rhodamine 6G was used to verify the activity of efflux pumps. The results showed that the isolates studied belonged to the species Candidozyma haemuli, Candidozyma duobushaemuli and Candidozyma heveicola. Among the yeasts studied, it was possible to find isolates (Y6065, Y7127, Y6408, Y7469 and Y7575) that were genetically distinct from the other species of the clade, and thus it was possible to find five new species belonging to the genus, named, in the present work, as Candidozyma sp. (1) – (2) – (3) – (4) – (5). Regarding virulence studies, we observed that all isolates were able to grow at 37°C, and seven isolates were also able to grow at 42°C. In addition, biofilm formation was observed in eleven isolates. One isolate from the Amazon (Y6408) and six isolates from Tocantins (Y6065, Y6066, Y7528, Y7529, Y7530 and Y7531) showed resistance to fluconazole and itraconazole, in addition to a dose dependence for amphotericin B and epoxiconazole. Regarding the new species identified in the present study, we observed that they presented a susceptibility profile to antifungals and virulence quite similar to the others studied. Candidozyma sp. (4) with high MIC for the azole class and amphotericin B, in addition to constitutive expression of the efflux pump in the presence and absence of fluconazole in isolate Y6066. The other species of the Candidozyma sp. group (2), (3) and (5) were dose-dependent for these classes, while Candidozyma sp. (1) was susceptible to all antifungals tested. In the present study, it was also possible, from the sequencing of the entire genome of the isolate UFMG-CM-Y6065, Y6408, Y7127 and Y7469, to perform genetic analyses to find genes related to antifungal resistance such as the ERG11 genes, genes related to biofilm formation and adhesion such as the ALSs, EFG1, SAPs, UPC2 genes and genes related to the efflux pump such as TAC1, CDR1, CDR2, CDR3, MDR1 and SNQ2. The results highlight the importance of continued investigations into the ecology and antifungal resistance of environmental yeasts, especially in a climate change scenario that favors the adaptation of these organisms and the emergence of new pathogens. It is concluded that the interaction between environmental factors and selective pressures, such as the use of antifungals, plays a crucial role in the evolution of the Candidozyma haemuli-auris complex, highlighting the need for integrated environmental surveillance to anticipate and mitigate the emergence of resistant strains with opportunistic potential.