Quantitative screening for fluconazole-amphotericin B antagonism in several Candida albicans strains by a comparative agar diffusion assay.

Antagonism between fluconazole (FCZ) and amphotericin B (AMB) was determined with an agar diffusion technique using series of agar plates containing no or 10 mgl-1 FCZ (comparative diffusion assay). Serial dilutions of AMB produced concentration-dependent inhibition zones that varied between the two agar plate series. This technique served as screening method to determine FCZ-AMB interactions in 18 Candida albicans strains. The critical concentrations of AMB were enhanced 1.33- to 7.0-fold by FCZ. The critical time, T0, was reduced by half by FCZ.