Identificação molecular, caracterização dos fatores de virulência e perfil de susceptibilidade antifúngica de isolados de Trichosporon spp

Abstract

Yeasts belonging to the genus Trichosporon emerge as emerging pathogens with high mortality rates. Primarily, Trichosporon species are etiological agents of white piedra, a fungal infection characterized by nodules adhered to the extrafollicular region of the hair shaft. However, in recent decades, Trichosporon spp. have been considered opportunistic pathogens responsible for severe communities. The number of researches involving the genus Trichosporon is still scarce, with little information available on the profiles of sensitivity to antifungal agents, expression of virulence factors “in vitro” and the actual distribution of the species in the different sites of infection. The objectives of this study were to carry out a molecular identification (IGS1 region of the rDNA) of Trichosporon spp. transmitted from white “piedra”, as well as determining the expression of “in vitro” virulence factors, including: DNases, hemolysins and phospholipases activity, ability to adhere to epithelial cells, cell surface hydrophobicity, melanin and biofilm production, in addition to evaluating fungal growth in the presence of cellular stressors. Also determine the antifungal susceptibility profile of clinical isolates of Trichosporon spp. and the results were compared to systemic infection strains. We identified 4 T. asahii isolates, 17 T. inkin isolates, 2 T. faecale and 2 T. asteroides isolates. Phylogenetic analysis revealed a higher degree of genetic relatedness (high bootstrap value) between T. asahii, T. asteroides and T. faecale, with T. inkin being considered a less closely related species. T. inkin isolates were more prevalent in clinical samples from patients with white piedra, in addition to showing greater ability to adhere to epithelial cells. The T. asahii isolates showed higher capacity for biofilm formation, cell surface hydrophobicity and hemolytic index. All evaluated isolates were able to produce hemolysins and DNases, whereas melanin production in Niger Seed Agar was not detected. Phospholipase production was negative for all tested isolates, except for two strains of T. inkin, which showed a high Pz value (low enzyme production). Several isolates considered minimal inhibitory concentrations and high epidemiological cut-off values, with a tendency to multidrug resistance to azoles (ketoconazole, itraconazole and fluconazole) and amphotericin B. Although the present study included few T. asahii isolates, they were captured this species, in general, stands out in the expression of virulence factors and resistance to antifungal agents, reinforcing its importance in invasive trichosporonosis.