Microbiology Practice Exam

Yeast infections, such as thrush, are primarily caused by Candida albicans, a type of fungus that is a member of the Candida genus. This organism is normally found in small amounts in the mouth, digestive tract, and on the skin of healthy individuals. However, certain conditions, such as a weakened immune system, antibiotic use, or hormonal changes, can lead to an overgrowth of Candida albicans. This overgrowth can result in infections, with thrush being a common manifestation characterized by white patches in the mouth and throat.

The other options listed represent different types of fungi but are not implicated in yeast infections like thrush. Aspergillus is known for causing respiratory infections, Penicillium is associated with food spoilage and antibiotic production, and Rhizopus is typically recognized for causing bread mold and can lead to other types of infections but not thrush. Therefore, Candida albicans is the correct and relevant choice when discussing yeast infections.