Prophylactic effect of Enterococcus faecalis FK-23 preparation on experimental candidiasis in mice

The prophylactic effects of heat-killed cells of Enterococcus faecalis FK-23 (FK-23 preparation) on experimental candidiasis were investigated in normal and leukopenic mice. In cyclophosphamide-induced leukopenic mice, oral or intraperitoneal administration of the FK-23 preparation at a daily dose of 1.25 or 5 mg/mouse for 3 consecutive days prior to Candida albicans infection significantly prolonged survival periods of the infected mice, and decreased viable counts of C. albicans recovered from their kidneys. In normal mice, the FK-23 preparation administered at dosages ranging from 0.63 to 10 mg/mouse/day for 3 consecutive days was ineffective, while in leukopenic mice, the FK-23 administered orally caused a facilitated recovery in the number of white blood cells including neutrophils. Furthermore, intraperitoneal administration of the FK-23 preparation into mice augmented the anti-Candida activity of immunocompromised peritoneal exudate cells obtained from the animals. These results suggested the potential usefulness of the FK-23 preparation as a prophylactic agent for the management of patients with opportunistic fungal infections.