Intracellular killing of Candida albicans by human neutrophils is potentiated by exposure to combinations of amphotericin B and 5-fluorocytosine

Combination treatment with amphotericin B and 5-fluorocytosine is synergistic and has become clinically useful in the treatment of various forms of systemic candidosis. The synergy between these two compounds may be explained in part by their combined effect on the interaction between fungal cells and host phagocytes. Pretreatment of Candida albicans for 2 h with either amphotericin B or 5-fluorocytosine or the two agents in combination did not inhibit or enhance phagocytosis by glass-adherent human neutrophils (P > 0.05). Intracellular killing of pretreated yeast cells was not influenced by antifungals alone (P > 0.05), but pretreatment of C. albicans with 5.0 mg l-1 amphotericin B + 10 mg l-1 5-fluorocytosine or 5.0 mg l-1 amphotericin B + 50 mg l-1 5-fluorocytosine significantly enhanced the ability of neutrophils to kill the number of viable yeast cells intracellularly (P <0.001).