Which organism is commonly associated with oral or vaginal thrush?

Candida albicans is the organism most commonly associated with oral or vaginal thrush, conditions characterized by the overgrowth of this yeast in mucosal membranes. Thrush occurs when there is an imbalance in the normal microbial flora of the body, often due to factors like antibiotics, hormonal changes, or a weakened immune system.

In oral thrush, it manifests as white patches in the mouth and throat, while in vaginal thrush, it results in itching, irritation, and a discharge. Candida albicans is part of the normal microbiota but can become pathogenic under certain conditions, leading to these infections.

The other organisms listed do not typically cause thrush. Trichophyton is primarily associated with dermatophyte infections like athlete's foot and ringworm. Aspergillus niger is a type of mold that can cause respiratory issues, mostly in immunocompromised individuals but is not linked to oral or vaginal thrush. Penicillium is another type of mold known for its role in food spoilage and antibiotic production but does not cause thrush. Thus, Candida albicans is clearly the correct answer due to its direct involvement in these specific infections.