A modern doctor working suddenly in a pre-scientific world. This is a lot like the manga "Jin", about a surgeon sect back in time to just before the Meiji Restoration. Dr. Jin was ingenious in his creation of highly purified ethanol and there was a ton of time and effort expended culturing penicillin. The method used for its purification was really ingenious, and he was able to borrow the microbiological expertise of a soy sauce brewer, whose workers were already skilled in asceptic techniques to prevent contamination of their normal fermented products.