Trichosporon identification methods for isolates obtained from different clinical specimens

Trichosporon is a medically important genus that includes the causative agents of both deep-seated, mucosa-associated infection and superficial infection. In this study, we aimed to present data on the phenotypic and molecular identification of Trichosporon species recovered from various clinical specimens representing both superficial and systemic infections. 397 samples ( 65 blood cultures, 192 nail scrapings, 140 skin scrapings) were included for isolation, phenotypic and genotypic identification of Trichosporon species. Cases of hematological malignancies, onychomycosis, and Tinea pedis were positive for yeast isolates with percentage of 10.7, 16.6, 20.7\%, respectively. Based on the morphologic characters of isolated colonies on Sabouraud dextrose agar (SDA), microscopic examination of colonies on rice agar, and stained smears, yeasts identified as Trichosporon were: 9(4.68\%) from nail samples, and 5(3.6\%) from skin samples and 0(0.0\%) from blood cultures. Polymerase chain reaction (PCR) using Trichosporon genus specific primers for 68 yeast isolates was positive in 16 samples (14 were previously identified by morphology and 2 nail scrapings were falsely diagnosed negative) at 170 bp. We subsequently performed 2 PCR runs on the identified 16 samples using specific primers for each of T. asahii and T. mucoides. Their sequences included ITS1, ITS2. They yielded specific amplification of a DNA fragment at 430 bp in 13(16) samples, which is specific for Trichosporon asahii, and 0(0.0\%) sample was positive for Trichosporon mucoides specific primers. Occurance of trichosporonosis is not rare in human. T. asahii species is common in our locality. Molecular methods for identification of Trichosporon are more precise. The standardization of laboratory methods for trichosporon identification and antifungal susceptibility tests are necessary to investigate for both superficial and systemic trichosporonosis.