Objectives: We prospectively performed antifungal susceptibility testing using the E-test (ETdir) on direct blood samples from 163 patients (225 strains), and on 63 strains artificially inoculated in BACTEC. ETdir MICs (24 h of incubation) of amphotericin B, fluconazole, voriconazole, posaconazole, Isavuconazole, and caspofungin were compared with results using CLSI M27-A3.
Methods: Strains were from highly fluconazole-susceptible species (FLUCO-S: 93 C. albicans, 77 C. parapsilosis, 18 C. tropicalis, 6 C. dubliniensis, 1 C. neoformans, 1 C. kefyr), or less fluconazole-susceptible species (FLUCO R: 52 C. glabrata, 29 C. krusei, 8 C. guilliermondii, 2 R. mucilaginosa, 1 T. mucoides). Voriconazole breakpoints were used for posaconazole and Isavuconazole (R ≥ 4 μg/mL). Strains were classified as susceptible (S) or resistant (R) following the CLSI procedure. The percentage of strains correctly classified by ETdir was calculated.
Results: Major discrepancies (M: R by ETdir and S by CLSI) were found mostly for C. glabrata, C. krusei and the triazoles. Very major discrepancies (VM: S by ETdir and R by CLSI) were found for fluconazole in C. krusei (n=2), and for voriconazole in C. glabrata (n=1) and T. mucoides (n=1)
Conclusions: ETdir in yeast-positive blood cultures is rapid (24 h) and easy, and reliably determines the antifungal susceptibility to triazoles and caspofungin of yeasts (especially highly fluconazole-susceptible species) from fungemic patients.
- ECCMID 20th (2010)