Yellow root, like all plants/herbs has many chemical constituents. One of the most notable has been shown via research to have anitmicrobial activity (fights bacteria, viruses, fungi, helminth worms, and protozoa). It also has anti-inflammatory action.
In tincture form, yellow root may also assist with conditions such as: BV, trichomoiasis and vaginal yeast infections.
In traditional herbalism (think back to your grandmother or great-grandmother), yellow roots was commonly used in those with intestinal distress (which may or may not be due to infection). It has been successfully used to assist in the treatment of peptic ulcers (most commonly PUD is associated with a bacterial infection).
Infused, you could use yellow root topically to help prevent skin infections (use as a wash for wounds), as it is antimicrobial.