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

OBJECTIVES: Molecular 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 METHODS: Fifty-five Trichosporon strains were characterized using IGS-1 sequencing from 2006 to 2018 and tested against 5 antifungals using CLSI M27-A3 guidelines. RESULTS: In 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 â€‹mg/l) resistance but relatively higher in fluconazole (range 0.25-64 â€‹mg/l). Although, comparatively low MIC ranges were found in the case of voriconazole (0.03-1 â€‹mg/l), posaconazole (0.06-1 â€‹mg/l) and itraconazole (0.06-1 â€‹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. CONCLUSION: T. 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.

Faster and accurate identification of clinically important Trichosporon using MALDI TOF MS.

PURPOSE: Trichosporon species are emerging human pathogens, accounting for the second most common cause of non-candidal mycosis. Rapid and reliable identification of these agents allows a better understanding of their epidemiology and therapeutic management. The Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) technique has the potential to be precise, fast and cost-effective. However, the precision of identification totally depends upon the type of protein extraction method used and embedded database in the system. Our objectives were to standardize the protein extraction technique and expand the present Bruker database by creating an in-house database and validating it with diverse clinical Trichosporon species of Indian origin. METHODS: Two different protein extraction protocols (on-plate and off-plate) were evaluated. The off-plate protocol was finalized for the identification. MALDI TOF MS with the existing Bruker database was evaluated for its ability to identify a total of 79 intergenic spacer 1 (IGS1) gene sequence confirmed clinical isolates of 5 different Trichosporon species. RESULTS: As outcome, off plate protocol yielded higher accuracy (73% on the species level and 95% on the genus level) than on-plate (25% on the genus level) in terms of log scores. The existing database for Trichosporon species was enriched with 28 sequence confirmed isolates, which improved accuracy from 73% to 100% and were identified up to species level with a log score >2.3. CONCLUSIONS: Used with standardized protein-extraction protocol along with an expanded database, MALDI-TOF MS could be a rapid and reliable approach to identify clinical Trichosporon species routinely in the laboratory.

Molecular characterisation and antifungal susceptibility of clinical Trichosporon isolates in India.

In Asian countries, Trichosporon infection is a well-known disease in Japan. In India, the infection is increasingly recognised. The study was conducted to characterise the clinical Trichosporon isolates from India by phenotypic and molecular techniques. A total of 31 Trichosporon clinical isolates, recovered from patients of 14 hospitals across India were sequenced (ITS and IGS1 regions of rDNA). In vitro drug susceptibility testing of the isolates was performed against amphotericin-B, fluconazole, itraconazole, voriconazole and posaconazole. IGS1, rather than ITS sequences, correctly identified the isolates: Trichosporon asahii, 20; Trichosporon ovoides, 3; Trichosporon inkin, 2; Trichosporon asteroides, 1; Trichosporon mucoides, 1; Trichosporon loubieri, 1; Trichosporon debeurmannianum, 1; and Trichosporon dermatis, 1. Trichosporon asahii genotype III was the most common type, followed by genotype I and VII. Both these targets did not help to identify one Trichosporon to the species level. Trichosporon debeurmannianum, T. dermatis and T. asteroides were isolated for the first time from a human disease in India. The minimum inhibitory concentrations for voriconazole and posaconazole were within effective range. The study highlights the presence of wide range of Trichosporon species causing infection in India. Voriconazole or posaconazole may be the better drugs to treat such patients.

Non-healing ulcer due to Trichosporon loubieri in an immunocompetent host and review of published reports.

We report here a case of non-healing ulcer due to Trichosporon loubieri in an apparently immunocompetent female. The identity of isolate was confirmed by DNA sequencing of D1/D2 region of 26S rDNA. The minimum inhibitory concentrations of the isolate were amphotericin B-0.5 µg/ml; fluconazole-4 µg/ml; posaconazole-0.25 µg/ml; voriconazole-0.06 µg/ml. The patient was managed by extensive debridement and oral fluconazole 150 mg daily for 6 weeks. She responded to therapy. To the best of our knowledge, till date, this is the fourth report of human infection due to T. loubieri and the first of its kind in an immunocompetent host. A review of published literature on infections due to T. loubieri is also included.