Characterization of Trichosporon species isolated from clinical specimens in Kuwait

Abstract

Invasive trichosporonosis is an emerging infection of severely immunocompromised patients. It is principally caused by Trichosporon asahii, although some other species of the genus have also been implicated in the aetiology. In this work, 29 clinical isolates of Trichosporon species recovered from 29 different patients over a 6-year period were studied for phenotypic and genotypic characteristics. Two morphotypes were recognized on the basis of colony characteristics. The colonies of 25 isolates appeared flat and centrally wrinkled, while the other four isolates appeared dry and irregularly folded or verrucosed. Based on substrate assimilation profiles, all 29 isolates were identified as T. asahii using the Vitek 2 system. However, PCR amplification of rRNA gene sequences identified only 25 of the 29 isolates as T. asahii. The identity of the remaining four isolates was established as Trichosporon asteroides by direct DNA sequencing of the internally transcribed spacer (ITS)-1 and ITS-2 regions in the rRNA gene fragment amplified by PCR using panfungal primers. Fingerprinting carried out by randomly amplified polymorphic DNA analysis showed genotypic heterogeneity among the 25 T. asahii and four T. asteroides isolates. These data suggest that T. asahii is the major species associated with clinical specimens in Kuwait.