[Post-antibiotic effect and post-exposure polyene antagonism of azole antimycotics in Candida albicans: dependency on...

With the lipophilic azoles itraconazole (ICZ), ketoconazole (KCZ), and miconazole (MCZ) two effects, occurring in parallel, on Candida albicans were observed: Firstly, these azoles caused a growth inhibition which persisted for at least 24 hours (post-antibiotic effect, found regularly with KCZ and MCZ, with ICZ only occasionally). Furthermore, the fungicidal activity of amphotericin B (AMB, 1 mg/1) after exposure to the azoles was reduced. In contrast, to this, fluconazole (FCZ) produced neither of these effects. Additional experiments indicate that both actions of the three lipophilic azoles may be related to their noncovalent binding to lipophilic cytoplasmatic components of the yeast cells. In the case of fluconazol such bonds seem to be much weaker. Presumably, the amount of the relatively hydrophilic fluconazole, which will be bound to the cell, is too low as to produce long lasting post-exposure effects like those caused by the lipophilic azoles.