Trichosporon asahii is considered an opportunistic pathogen responsible for severe infections, mainly in immunocompromised patients. The aims of this study were to investigate the prevalent genotypes among 39 clinical isolates of this microorganism by sequencing the IGS1 region and to determine the in vitro production of DNAse, hemolysin, aspartyl proteinase, phospholipase and esterase, as well as the susceptibilities of the isolates to amphotericin B, anidulafungin, micafungin, caspofungin, voriconazole, posaconazole, fluconazole and 5-flucytosine. Our findings showed that genotype I was the most prevalent comprising 69.23% of the isolates. We confirmed the production of esterase for all our isolates, and report the production of DNAse and aspartyl proteinase in 84.62% and 23% of the isolates, respectively. Only one isolate of T. asahii produced hemolysin. None of the isolates showed phospholipase activity. Fifty-three percent of the T. asahii strains exhibited amphotericin B MICs ≥ 2 μg/ml. The three echinocandins evaluated yielded high MICs (≥2 μg/ml) in all isolates. Thirty-five percent of the isolates had high MICs for 5-flucytosine (≥32 μg/ml), and 97% of the isolates were susceptible to the evaluated triazoles.

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Candida bracarensis is an emerging cryptic species within the Candida glabrata clade. To date, little is known about its epidemiology, virulence, and antifungal susceptibility. This study documents the occurrence of C. bracarensis for the first time in Mexico and focuses on its in vitro production of hydrolytic enzymes, as well as antifungal susceptibility to echinocandins. This strain was isolated from a vaginal swab of a female with vulvovaginal candidosis; exhibited a very strong activity of aspartyl proteinase, phospholipase, and hemolysin; and was susceptible to caspofungin, anidulafungin, and micafungin (MIC = 0.031 μg/mL). Data obtained could contribute to the knowledge of the epidemiology and virulence attributes of this yeast as a fungal opportunistic human pathogen.

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Trichosporon asahii is an opportunistic yeastlike fungus that colonizes the gastrointestinal and respiratory tracts and human skin. Although it is an important cause of disseminated infections by non-Candida species, there are a few reports related to its virulence factors and their possible role in in vivo pathogenicity. We developed a murine model of disseminated trichosporonosis in immunocompetent mice for the evaluation of the in vivo pathogenicity of 6 T. asahii isolates with different in vitro virulence factor profiles. Tissue fungal burden was determined on days 1, 3, 7, 15, and 25 post-challenge. Overall, the largest fungal load was detected in the kidney on the 5 experimental days, while brain, spleen, and liver displayed a comparatively low fungal count. We observed a fungal burden decrease in most experimental groups from day 15. Histological analysis showed the presence of T. asahii in tissue and a generalized inflammatory infiltrate of polymorphonuclear cells in the kidney, liver, red pulp of the spleen, and the hippocampus. Even though our isolates showed different in vitro virulence factors profiles, we did not detect relevant differences when assayed in vivo, except for a higher persistence of a protease- and biofilm-producing strain in kidney, liver, and brain.