POSTANTIFUNGAL EFFECT AND EFFECTS OF LOW CONCENTRATIONS OF AMPHOTERICIN-B AND FLUCONAZOLE ON PREVIOUSLY TREATED CANDIDA-ALBICANS

The objective of the study was to assess (a) the postantifungal effect (PAFE) of amphotericin B (AmB) and fluconazole (Flu) an two Candida a lbicans strains, and (b) the effect of low concentrations of AmB or Fl u on yeasts previously exposed to AmB or Flu, respectively, in the pre sence or absence of 10% human serum. In the absence of serum, AmB exer ted a positive effect (at 0.5-5.0 h) depending on the concentration an d the strain used. Flu, however, produced negative effects (at -1.2 to -0.1 h), When the experiment was conducted in the presence of serum, the duration of all PAFEs increased significantly, especially those in duced by Flu that became positive, Pretreated yeasts were more suscept ible than untreated controls to the antifungal activity of low concent rations of the drugs. Growth delay was more pronounced with Flu (up to 5.2 h), whereas the greatest decrease in log,, at 12 h was slightly m ore pronounced for AmB, A knowledge of PAFEs and the effects of low dr ug concentrations on pretreated yeasts and the effects of serum on the se is important in order to gain more insight into the in vivo activit y of the study drugs.