In vitro susceptibility testing of amphotericin B for Cryptococcus neoformans variety grubii AFLP1/VNI and Cryptococcus gattii AFLP6/VGII by CLSI and flow cytometry

摘要

Cryptococcus neoformans var. grubii AFLP1/VNI is the main causative agent of cryptococcosis associated with AIDS in the world. Cryptococcus gattii AFLP6/VGII causes mainly endemic primary infection in immunocompetent hosts. To determine the minimum inhibitory concentrations (MICs) of C.neoformans var. grubii AFLP1/VNI and C.gattii AFLP6/VGII against amphotericin B (AMB) in a short period of time, flow cytometry (FCM) with FUN-1 fluorochrome was used to compare with broth microdilution method (CLSI M27-A3). The minimum incubation period was evaluated by minimum fungicidal concentration procedure. Seventeen clinical isolates of C.neoformans var. grubii AFLP1/VNI and 18 of C.gattii AFLP6/VGII were analysed. The time for the determination of MICs by FCM was 2h against 72h by CLSI M27-A3 and the comparison of MIC showed a positive significant correlation (P=0.048). It is important to highlight the role of the FCM as an alternative method to determine the MICs for AMB in within a day, with positive cost-benefit.