Fluorescent antibody stain micrograph of oval budding Candida albicans. Candida albicans is a yeast that inhabits the mouth, throat, intestines and urinary tract of humans. C. albicans recognize and destroy harmful bacteria. The immune system and "friendly" bacteria usually control the growth of C. albicans. However, if the number of bacteria is decreased (through antibiotics), the immune systems is weakened, or other conditions for yeast proliferation occur (a diet high in sugar), C. albicans will shift from yeast to mycelial fungal form, producing rhizoids, root-like structures that penetrate intestinal walls, allowing toxins, undigested food, bacteria, and yeast to enter the bloodstream. Overgrowth of C. albicans can also lead to vaginitis and oral thrush.