All of the questions in this comment thread are towards creating an antibiotic in an extreme emergency situation. Yet all of the answers involve activities that require refrigeration and pressure heating: both of which require electricity. If the power is on then the drug store is probably open. Unless you're on a solar powered generator. It also involves having a lot of complicated ingredients that you won't have on hand unless you can use common things that contain them.
So question 1: How long does drug store penicillin remain viable against bacterial infections?
and question 2: How effective would a primitive cocktail of milk, crushed vitamins, sugar, cornstarch, epsom salts, beef jerky and Gatorade be as a media?
Again - it's an extreme survival question only.
