AMPHOTERICIN-B SUSCEPTIBILITY OF CANDIDA SPECIES ASSESSED BY RAPID FLOW CYTOMETRIC MEMBRANE-POTENTIAL ASSAY

A method for detection of the susceptibility of Candida species to amp hotericin B is described. The technique is a modification of a similar flow cytometric technique designed to detect antibiotic susceptibilit y of Staphylococcus aureus, Membrane potential changes caused by the a ntibiotic are measured flaw cytometrically by using the fluorescent me mbrane potential-sensitive dye 3,3'-dipentyloxacarbocyanine iodide. On e strain each of C. albicans and C. tropicalis (both sensitive to amph otericin B) and one strain of C. tropicalis (resistant to amphotericin B) were used to validate the method. Sensitivity or resistance was ea sily determined after 30 min of incubation in the presence of the anti biotic, and the drug effect was evident in a dose-dependent manner. (C ) 1995 Wiley-Liss, Inc.