Evaluation of a flow cytofluorometric method for rapid determination of amphotericin B susceptibility of yeast isolates.
A rapid-flow cytofluorometric susceptibility test for in vitro amphotericin B testing of yeasts was evaluated and compared to the National Committee for Clinical Laboratory Standards (NCCLS) M27-T reference broth macrodilution method. The flow cytofluorometric method is based on the detection of decreased green fluorescence intensity of cells stained with DiOC5(3), a membrane potential-sensitive cationic dye, after drug treatment. Testing was performed on 134 clinical isolates (Candida spp. and Torulopsis glabrata). From the dose-response curve obtained for each isolate, three endpoints were calculated by computer analysis (the concentrations at which the fluorescence intensity was reduced by 50, 80, and 90%, i.e., 50% inhibitory concentration [IC50], IC80, and IC90, respectively). A regression analysis correlating these endpoints with the M27-T MICs showed that the best agreement was obtained with IC80. The flow cytofluorometric method showed good reproducibility with control strains. These initial results suggest that the flow cytofluorometric method is a valid alternative to the NCCLS reference method.
Peyron
F
F
Laboratoire de Botanique, Cryptogamie, et Biologie Cellulaire (PAON, EA 864), Faculté de Pharmacie, Université de la Méditerranée, Marseille, France.
Favel
A
A
Guiraud-Dauriac
H
H
El Mzibri
M
M
Chastin
C
C
Dumenil
G
G
Regli
P
P
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects*; D003201:Computers; D005069:Evaluation Studies as Topic; D005434:Flow Cytometry; D008826:Microbial Sensitivity Tests; D012044:Regression Analysis; D013997:Time Factors
D000935:Antifungal Agents; D000666:Amphotericin B