I'm pretty sure the only real reason why she shouldn't is if she needs to take the antibiotics with food, as is the case with some medication. I'm always on the blasted things (or so it seems anyway) and often the GP has said "make sure you take it before (or after in some cases) food". So if that's the case she would need to eat something, but otherwise I don't think there should be a problem.
Sure a CDC will be along to advise but this is my understanding as my CDC explained to me.
xxx