Resistance of Virulent and Attenuated Strains of Candida Albicans to Intracellular Killing by Human and Mouse Phagocytes

Blastospores of two strains (no. 19321 and no. 19273) of Candida albicans that were obtained from patients with vaginal thrush and were virulent for mice showed no significant difference in degree of resistance to phagocytosis by human and mouse phagocytes (mostly polymorphonuclear) compared with blastospores of two strains (no. 22114 and no. 21462) that were isolated from patients with transient candidemia and were attenuated for mice. In contrast, more blastospores of the virulent strains survived intracellularly than did those of the attenuated strains over a 2-hr period, after which the surviving blastospores began to form germ tubes. Heterogeneity in the populations of blastospores was suggested, because progeny from surviving blastospores of attenuated strain no. 22114 behaved similarly to virulent strains in tests with human and mouse phagocytes and in virulence tests in mice.