Genotyping, extracellular compounds, and antifungal susceptibility testing of Trichosporon asahii isolated from Mexican patients

Abstract

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.

Keywords: T. asahii; extracellular compound; genotype; in vitro susceptibility.