Molecular investigation of azol resistance mechanism in candida strains isolated from blood culture

In our study, it was aimed to identify Candida species isolated from blood culture, to determine their antifungal susceptibility and molecular determination of azole resistance mechanisms. A total of 100 Candida strains isolated from blood culture were included in the study. As a result of species-level identification, 41 of the strains were C.albicans, 22 were C.parapsilosis, 14 were C.glabrata, 13 were C.tropicalis, 5 were C.lusitaniae, 3 were C.guillermondi, 1 was C.krusei, 1 was identified as C.kefyr. Of the strains included in the study, 78% were isolated from the intensive care unit, 16% from the internal services, and 6% from the surgical services Antifungal susceptibility testing was performed on C.albicans, C.parapsilosis, C.glabrata and C.tropicalis strains. In vitro antifungal susceptibilities of the strains for fluconazole, posaconazole, voriconazole, amphotericin B, kaspofungin and micafungin were determined. While 2% of the C.albicans strains were resistant to fluconazole and 15% to voriconazole, 5% of the strains were found intermediate resistant to voriconazole and 10% to micafungin. While 34% of C.albicans strains were found as non-wild type for amphotericin B, 7% for posaconazole; all strains were found susceptible to caspofungin. Twenty three percent of C.parapsilosis strains were resistant to fluconazole and 23% were dose-dependent susceptible. While 50% of the C.parapsilosis strains were found intermediate susceptible to voriconazole and 14% to micafungin, all strains were found susceptible to caspofungin. 59% of the strains were found non-wild type for amphotericin B and 5% for posaconazole. Twenty one percent of the C.glabrata strains were found fluconazole resistant, 79% were dose-dependent susceptible to fluconazole. While 7% of C.glabrata strains were micafungin resistant; 64% of the strains were found intermediate susceptible to micafungin and 7% to caspofungin. While 71% of the strains were found as non-wild type for amphotericin B, 57% for voriconazole, all of the strains were wild type for posaconazole. While all C.tropicalis strains were found susceptible to fluconazole and caspofungin; 15% of the strains were found intermediate susceptible to voriconazole and 15% to micafungin. 77% of the strains were found to be non-wild type for amphotericin B and 8% to posaconazole. According to the antifungal susceptibility test, expression levels of ERG11, CDR1, CDR2 and MDR1 genes were calculated in the fluconazole-resistant 3 C.glabrata, 5 C.parapsilosis, 1 C.albicans and fluconazole dose-dependent susceptible 11 C.glabrata, 5 C.parapsilosis strains. The number of folds the genes were expressed was calculated by comparing the results with the control ATCC strains. Accordingly, over expression of ERG11 and CDR1 was found in all fluconazole-resistant C.glabrata strains, and over expression of CDR2 was found in 67% of them. In all fluconazole dose dependent susceptible C.glabrata strains over expressed ERG11 and CDR1 genes, while 91% of them over expressed CDR2 genes. MDR1 genes were overexpressed in all fluconazole resistant C.parapsilosis strains, and ERG11 and CDR1 genes were overexpressed in 80% of them. ERG11, CDR1, MDR1 genes were overexpressed in 80% of fluconazole dose-dependent susceptible C.parapsilosis strains. In fluconazole resistant C.albicans strain, ERG11 and CDR1 genes were found overexpressed.