Prevalence and Antifungal Susceptibility of the Emerging Fungal Species, Candida nivariensis, Isolated in a Teaching Hospital in Poland

The data on susceptibility to antifungals of new species within Candida glabrata complex are limited. Our study was to enrich a global knowledge of yeast epidemiology and drug resistance. The study was focused on the identification of species within clinical isolates of the C. glabrata complex and on the determination of their resistance to antifungals. Four hundred forty-five clinical C. glabrata sensu lato strains were isolated from different clinical samples at routine mycological exams at the Infant Jesus Teaching Hospital in Warsaw. The identification of the most of tested isolates to species complex level was performed using the ID 32 C system. The identification of C. nivariensis and C. bracarensis species within the C. glabrata complex was performed by DNA sequencing. The MICs of amphotericin B, fluconazole, itraconazole, posaconazole, voriconazole, caspofungin, anidulafungin, and micafungin were determined by E-test. Twenty-four isolates did not have an ITS-1 region, characteristic of C. glabrata sensu stricto and their D1/D2 regions of the 26S rRNA were 99% homologous to C. nivariensis 26S rRNA. No strains of C. bracarensis were recovered. C. nivariensis strains were very susceptible to amphotericin B, anidulafungin, micafungin, and caspofungin. Ninety-two percent of C. nivariensis were resistant to itraconazole. The halves of the strains was resistant to posaconazole. Eighty-three percent of C. nivariensis were susceptible to voriconazole. None of the tested strains were susceptible to fluconazole. In the present study, none of the C. nivariensis strains were simultaneously resistant to azoles and echinocandins. C. nivariensis should be recognized as an emerging pathogen, resistant to azoles.