Wouldn't just going for penicillium or any other super powerful and natural bacteria killer be easier for her ?...
Find some mushroom nerds to prove your point first, then go straight to the synthesis of sulfanilamid or something similar. If she really was an expert in her previous life, this kind of easy synthesis process should take her a few days at most, and that's something you can teach anyone afterward.
Bacteria with resistance wouldn't exist, so any generic antibiotic would do as a stopgap measure.
While she's at it, go and craft a microscope. The concept isn't hard, a simple one will do, so just give the concept to any skilled craftman in the capital. Heck you can even teach them to do a proper mirror if they don't have the technology.