As I point out in by book (and have experienced in real life), having alternate antibiotics on hand is not necessarily of value unless you also have someone around who is qualified to diagnose.
I have a friend who is a nurse, who actually kept the doctor’s office going when the Doc became old and feeble. Plus I have a number of different Books I bought from the Med. School Book store in St. Louis.
There are also several sites on the internet that can help. The best thing in to keep clean, and have good nutrition so as to prevent sickness to begin with.