Absolutely... you can easily contract Chlamydia, Siphillis, Gonorhea, and a number of other bacterial STD's quite simply from fellatio. Also, if she has even the beginnings of a cold-sore or cankersores, or even if she wont show symptons or signs of either of the two for a week or two and she gives you head... youre looking at a transformation from Herpes Simplex Complex A, to Complex B. Oral to genital.

Even HIV... although extremely unlikely and instances are very very rare can be transmitted as such. As HIV content in saliva is nearly negligible, she would have to have a cut or open sore on the inside of her mouth, and she would have to tooth you pretty good or at least get you raw or something.

But yeah. Go get tested. And next time you come across a bitch like that... do just that. Jack off on her face and teeth and tell her she has the whitest smile you ever came across.