if you have had basics of genetics, i would take micro. micro WOULD help by giving you a basic foundation of microbes. aside from anatomy, i have been told micro tends to be most tedious/difficult for med students. i would suggest, however, if there is a medical micro class to take that instead, it'll probably be more interesting (pathogenesis of organisms, etc) and geared towards what you will be learning in med school.
just my opinion.