How do you write a doctoral degree acronym when using the "last name first" style?

How do you write a doctoral degree acronym when using the "last name first" style? I'm doing a Works Cited sheet in MLA style and the names have to be "last name first, first name last". But I need to put Ph.D on one, and MD on the other. I'm not sure whether I need to put it after the last name, or the first.