Well, any sort of bacteria can have an effect and fuck with the natural pH levels in the vagina. Some women are more sensitive to it than others, but getting your period usually helps stabilize the pH levels, and if it persists, homemade remedies can work wonders. Yogurt or a clove of garlic work wonders (I know, I know...), and if it's still there, she should go see a doctor. I've had an infection twice and it's mindnumbingly painful and irritating.