Flow cytometric assay for estimating fungicidal activity of amphotericin B in human serum.
We describe a simple and rapid bioassay for estimating fungicidal activity of Amphotericin B in human serum using flow cytometry. The method exploits the fact that Candida albicans damaged by Amphotericin B show a decrease in size and take up propidium iodide to exhibit a red fluorescence after deoxycholate treatment. These phenomena display characteristic dose dependencies, and their assessment permits serum fungicidal activity to be broadly grouped into three categories: (1) subfungicidal; (2) fungicidal; and (3) strongly fungicidal. In normal human serum, these three categories correspond to Amphotericin B concentrations of 0 less than or equal to 0.5 micrograms/ml, 0.75-1.5 micrograms/ml, and greater than 2 micrograms/ml, respectively. Pilot analysis of serum samples obtained from four patients undergoing Amphotericin B therapy confirmed the feasibility of using the flow cytometric assay for estimating drug fungicidal activity ex vivo. The method is very simple, generates results within 5 h, and could prove useful for monitoring therapy with this effective but toxic drug.
Martin
E
E
Institute of Medical Microbiology, University of Mainz, Federal Republic of Germany.
Schlasius
U
U
Bhakdi
S
S
D000666:Amphotericin B / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects*; D002177:Candidiasis / Q000097:blood* / Q000382:microbiology; D015169:Colony Count, Microbial; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans
D000666:Amphotericin B