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.

Molecular Identification and Susceptibility ofTrichosporonSpecies Isolated from Clinical Specimens in Qatar: Isolation ofTrichosporon dohaenseTaj-Aldeen, Meis & Boekhout sp. nov

“…In the present study, T. inkin was isolated in cases of white piedra, balanitis, and urethral discharge. T. asteroides is known to have been isolated from skin (2,23) and from a patient with a nosocomial bloodstream infection (33). T. ovoides is not reported to cause systemic infections but is known to cause white piedra (14), and the species is isolated from the homes of patients with summertype hypersensitivity pneumonitis (67,68,72).…”

“…Trichosporon is considered an opportunistic agent, and therefore, recovery of Trichosporon species capable of growing at 37°C, especially from immunocompromised patients, should be regarded as potentially significant. Several reports have addressed the difficulty of identifying Trichosporon to the species level by physiological and biochemical characteristics (2,64); therefore, molecular methods based on the sequencing of the internal transcribed spacer (ITS) have been developed (15,69,71,72).…”

Bloodstream Infections Due to Trichosporon spp.: Species Distribution, Trichosporon asahii Genotypes Determined on the Basis of Ribosomal DNA Intergenic Spacer 1 Sequencing, and Antifungal Susceptibility Testing

“…For instance, it has been mentioned in the literature that an isolate identified by molecular methods as Trichosporon dermatis was mistakenly identified as Trichosporon mucoides when Vitek Systems 1 and 2 (BioMérieux, France) were used (16). Furthermore, Ahmad et al (1) reported that four isolates previously identified by Vitek 2 as Trichosporon asahii were identified as Trichosporon asteroides by molecular techniques. There is a consensus that molecular methods are required for accurate identification of this genus, but they are still costly and not suitable for most routine laboratories (38,42).…”

“…Phenotypic methods for Trichosporon species identification usually generate inconsistent results, and none of the commercial tests available include the whole new taxonomic categories in their databases (1,36,37). For instance, it has been mentioned in the literature that an isolate identified by molecular methods as Trichosporon dermatis was mistakenly identified as Trichosporon mucoides when Vitek Systems 1 and 2 (BioMérieux, France) were used (16).…”

A Trichosporon asahii Bloodstream Infection in a Preterm Newborn with a Successful Outcome: A Case Report

“…Trichosporon asahii (previously known as T. beigelii) is an emerging, opportunistic non-candida yeast pathogen that causes superficial dermatologic infections (white piedra and onychomycosis) in immunocompetent individuals, however, among immunocompromised patients, it causes severe complications, disseminated disease with poor prognosis and fatal infections for neonatal [3]. Prematurity is an important predisposing factors for invasive Trichosporon infections [4].…”