Intergenic spacer (IGS-1) region sequence-based identification, genotypic analysis, and antifungal susceptibility of clinical Trichosporon species

Abstract

ObjectivesMolecular genotyping of Trichosporon species using intergenic spacer region (IGS-1) sequencing and antifungal drug susceptibility testing of T. asahii clinical isolates from Indian patients. Materials and methodsFifty-five Trichosporon strains were characterized using IGS-1 sequencing from 2006 to 2018 and tested against 5 antifungals using CLSI M27-A3 guidelines. ResultsIn this study, broad-spectrum antibiotics with steroids, catheters, and ICU stays were major underlying risk factors. These cases were most commonly associated with diabetes (type-2), chronic obstructive pulmonary disease, and hypertension. Out of fifty-five isolates, 47 (85%) were identified as T. asahii, and the remaining 6 were T. inkin (11%) and 2 were Cutaneotrichosporon dermatis (3.6%). The most common genotype of T. asahii was G3 (22; 49%) subsequently G4 (12; 23%), G1 (8; 17%), and G7 (2; 4%). One new genotype of T asahii was found in addition to the fifteen already known genotypes. Indian T. asahii isolates showed a low level of amphotericin B (range 0.06–4 ​mg/l) resistance but relatively higher in fluconazole (range 0.25–64 ​mg/l). Although, comparatively low MIC ranges were found in the case of voriconazole (0.03–1 ​mg/l), posaconazole (0.06–1 ​mg/l) and itraconazole (0.06–1 ​mg/l). Voriconazole appeared to be the most active drug in T. asahii isolates. The MICs for all the drugs were comparatively lower in the case of non-Trichosporon asahii strains. ConclusionT. asahii was the most common Trichosporon isolate. Speciation is necessary for optimal antifungal therapy. Voriconazole-based treatment, Steroids, removal of catheters and control of underlying conditions results in positive outcomes.