Can a intravienious user (speed,coke)cause a drg free wm to test dirty thru unprotected sex(oral,anal,vaginal)?

I am a recovering addict that slipped last week. My girlfriend has a great job and we had sex approx 16 times in a four day span with no protection. I was informed subsequently by a unreliable source that it is possible for her to test positive. I've since restarted the recovery process but feel pretty bad about this and would like to know the truth. thanks, Trainwreck