Correlation of Trichosporon asahii Genotypes with Anatomical Sites and Antifungal Susceptibility Profiles: Data Analyses from 284 Isolates Collected in the Last 22 Years across 24 Medical Centers.

Abstract

Trichosporon asahii is an opportunistic fungal pathogen that can cause severe infections with high mortality rates. Azole derivatives are the best-targeted therapy for T. asahii invasive infections, but azole-resistant isolates have been reported. To investigate peculiarities in the antifungal susceptibility profile (ASP) of T. asahii clinical isolates, we analyzed the genotype distribution, isolation sources, and ASP of 284 strains collected from 1997 to 2019 in different Brazilian medical centers. Species identification and genotype characterization were performed by analysis of the intergenic spacer (IGS1) region of the ribosomal DNA (rDNA). Antifungal susceptibility testing (AST) for amphotericin B and azoles was with the CLSI M27, 4th edition, microdilution broth method. Trends in the ASP of Brazilian T. asahii isolates were investigated using epidemiological cutoff values. Five different genotypes were found among the 284 isolates tested (G1, 76%; G3, 10%; G4, 3%; G5, 7%; and G7, 4%). The isolates were collected mainly from urine (55%) and blood/catheter tip samples (25%) where G1 was the most frequent genotype found (P < 0.05). The G7 isolates exhibited the highest MIC90 values for azoles compared to those for the other genotypes (P < 0.05). Genotype 7 isolates also contributed to the increasing rates of voriconazole non-wild-type isolates found in recent years (P = 0.02). No significant differences were found among the AST results generated by isolates cultured from different anatomical sites. Monitoring T. asahii genotype distributions and antifungal susceptibility profiles is warranted to prevent the spread of azole-resistant isolates.