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Characterization of Trichosporon species isolated from clinical specimens in Kuwait
Suhail Ahmad1, Manal Al-Mahmeed1, Zia U Khan1
1Department of Microbiology, Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, 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.
Insights
Invasive trichosporonosis, often caused by Trichosporon asahii, affects immunocompromised patients. This study identified T. asahii in most clinical isolates, with Trichosporon asteroides also detected using molecular methods.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Molecular Biology
Background:
- Invasive trichosporonosis is an emerging opportunistic infection in severely immunocompromised individuals.
- Trichosporon asahii is the primary causative agent, though other species can be involved.
- Accurate identification of Trichosporon species is crucial for effective patient management.
Purpose of the Study:
- To characterize phenotypic and genotypic features of clinical Trichosporon isolates.
- To evaluate the accuracy of traditional identification methods versus molecular techniques.
- To determine the predominant Trichosporon species causing infections in Kuwait.
Main Methods:
- Phenotypic analysis of colony morphology and substrate assimilation.
- Vitek 2 automated system for initial species identification.
- Polymerase Chain Reaction (PCR) amplification of rRNA gene sequences.
- Direct DNA sequencing of Internal Transcribed Spacer (ITS) regions.
- Randomly Amplified Polymorphic DNA (RAPD) analysis for genotypic fingerprinting.
Main Results:
- Two distinct colony morphotypes were observed among the 29 clinical isolates.
- Vitek 2 identified all 29 isolates as T. asahii.
- Molecular methods confirmed 25 isolates as T. asahii and identified the remaining four as T. asteroides.
- RAPD analysis revealed genotypic heterogeneity within both identified species.
- T. asahii was confirmed as the major species associated with clinical specimens in Kuwait.
Conclusions:
- Molecular identification methods provide higher accuracy than phenotypic methods for Trichosporon species.
- T. asahii is the predominant species implicated in invasive infections in the studied population.
- Genotypic diversity exists within clinical isolates of T. asahii and T. asteroides.
- Further research is needed to understand the clinical implications of genotypic variations.
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