Epidemiology and Antifungal Susceptibility of Infections Caused by Trichosporon Species: An Emerging Non-Candida and Non-Cryptococcus Yeast Worldwide

Introduction: Over the past four decades, there has been an increase in the number of fatal opportunistic invasive trichosporonosis cases especially in immunocompromised hosts. Objective: The objective of the study is to evaluate the epidemiological, clinical details and antifungal susceptibility pattern of the patients with Trichosporon infections. Materials and Methods: Twenty-four clinical isolates of Trichosporon species isolated from blood, samples, pleural fluid and nail were included in this study, over a period of 12 years (2005-2016) in a tertiary hospital in North India. The isolates were characterised phenotypically and few representative isolates were sequenced also. The minimum inhibitory concentration (MIC) was determined as per Clinical and Laboratory Standards Institute, 2012. Results: Trichosporon spp. from blood culture (57.78%), nail (37.5%) and pleural fluid (4.17%). On phenotypic tests, 79.16% of the isolates were Trichosporon asahii, followed by Trichosporon dermatis (8.33%), Trichosporon japonicum (4.17%), Trichosporon ovoides (4.17%) and Trichosporon mucoides (4.17%). The MIC range of Trichosporon species from invasive infections were fluconazole (0.06-256 mu g/ml), amphotericin B (0.125-16 mu g/ml), voriconazole (0.0616-8 mu g/ml), posaconazole (0.0616-32 mu g/ml) and caspofungin (8-32 mu g/ml). The isolates from superficial infection were resistant to fluconazole (0.06-256 mu g/ml) and itraconazole (0.125-32 mu g/ml), all were susceptible to ketoconazole and while only two were resistant to voriconazole (0.25-4 mu g/ml). Conclusion: T. asahii was the most common isolate. Disseminated trichosporonosis is being increasingly reported worldwide including India and represents a challenge for both diagnosis and species identification. Prognosis is limited, and antifungal regimens containing triazoles appear to be the best therapeutic approach. In addition, accurate identification, removal of central venous lines and voriconazole-based treatment along with control of underlying conditions were associated with favourable outcomes.