Do ambiente ao hospedeiro: abordagem Saúde Única sobre a susceptibilidade e mecanismos de resistência em leveduras do gênero Trichosporon frente a antifúngicos clínicos, agroquímicos e sanitizantes in vitro e in vivo

Abstract

The Trichosporon genus comprises opportunistic yeasts widely distributed in the environment and present in the microbiota of humans and animals, capable of causing different types of infection. Invasive trichosporonosis is an emerging disease that primarily affects immunocompromised individuals, with clinical manifestations ranging from fungemia to meningitis. Within this genus, antifungal resistance has become increasingly common. However, the variability among species and the lack of standardized testing methods hinder accurate diagnosis and effective treatment, especially within the One Health context. In this study, antifungal resistance in Trichosporon spp. was investigated through a literature review combined with methodological analysis and standardization, using a collection of isolates obtained from clinical, animal, and environmental sources. First, a comprehensive review was conducted on intrinsic and acquired resistance in Trichosporon spp., including the mechanisms involved in resistance to major classes of clinical antifungals—polyenes, azoles, echinocandins, and flucytosine. The findings showed that these yeasts are intrinsically resistant to echinocandins and display low susceptibility to amphotericin B and azoles, with triazoles—particularly voriconazole—being the most effective drugs. Flucytosine, in turn, is not recommended for the treatment of trichosporonosis. Overall, resistance is primarily associated with mechanisms such as efflux pump activity, biofilm formation, and alterations in the cell wall and lipid membrane composition. Next, the broth microdilution methodology for Trichosporon spp. was investigated and standardized for amphotericin B and fluconazole. Based on this standardization, optimized conditions for determining the minimum inhibitory concentration (MIC) were established and applied in the experimental component of this study. Subsequently, susceptibility of the 33 isolates was assessed against clinical antifungals, disinfectants, and agrochemicals using the standardized method. Based on in vitro assays, twelve isolates were initially classified as resistant to clinical antifungals and potentially cross-resistant to agrochemicals and disinfectants. Additional assays, including growth evaluation and biofilm production, refined this selection, resulting in four isolates with more pronounced resistance profiles. These selected strains were then tested in a murine infection model, confirming resistance in vivo. Animals infected with the resistant isolates and treated with amphotericin B or fluconazole exhibited higher fungal burden, impaired recovery, and increased colonization of the central nervous system, suggesting a possible association between resistance, virulence, and treatment failure. Overall, this study provides a clearer understanding of resistance and its mechanisms within the Trichosporon genus, highlighting the emergence and impact of resistance and cross-resistance in the One Health context, and linking these findings with ineffective treatment and enhanced virulence.