That's basically the animal version of acidophilus. You can find it here.
Your problem with Aubrie goes way beyond that, though. We had a cat, Meisje, who eliminated in inappropriate places. She lived to be 21, and stopped the behavior as soon as her nemesis and resident bully Natasha passed away. So for the final 6 years of Meisje's life, she only occasionally pooped next to the litter box, and only if her son came along while she was trying to go.
I can't tell you what would fix her issues. Do you have a bully in the house that stalks Aubrie when she tries to use the litter box? Is there a way to distract the bully? There is one more thing you can try, which I'm actually using right now to eliminate stalker and drive-by attack behavior from one of my new bullies:
It's essential oil essences that you put into water or dribble onto the cat's fur. I didn't think it would work, but it really does! Our bully has mellowed out, and our resident victim has learned to stand up for himself. It's a set of three essences, although you can get individual bottles, as well. I'm honestly not sure how it works, but I was ready to try anything, because our Nicky was constantly harrassing our middle aged gentleman Samson to the point where poor Samson constantly had to look over his shoulder for a "hit and run", as I call them. He started peeing on the hardwood floor right in front on me, as if to tell me: "Ma, this has to stop, or I'll ruin your house".
The remedy takes a couple of weeks to work, so give it time. And I'd also recommend feliway plug-ins to go along with it. Especially in the litter box area. Good luck!