Get her prescribed a cream and then start using bag balm, it will keep all the bacteria off her skin. I swear by bag balm and you can use it for many different things so I suggest scooping some out into a different container that way whatever you are using to apply it, the rest of the can won’t get contaminated and you’ll have a designated container of it and the rest you can use for other things. It works on cuts and scraps, as lip balm, moisturizer...

Might sound crazy but- if you have breastmilk and she doesn’t mind- pump some then put it on the affected area and let it air dry. Keep the area clean and dry. BM is the best remedy for diaper rash in kiddos! Creams and powders just don’t do the same.

See if you can get her prescribed a cream, my kids have had prescriptions for something called Rileys Butt cream and it's amazing! It's a barrier cream with nystatin and a few other things that are good for your skin. With her being an adult, her urine and poop is going to be much stronger than a babies I would think. It might take a heavy duty cream to clear it up.

Use canestin the cream ...

I would get a big tub of Triple Paste. That stuff is a miracle worker.

Keeping it dry and adding barrier cream. I like the original clear A&D ointment