First let me advise you that I am not an MD, nor am I qualified or authorized to give medical advice to humans. Keep in mind, however, that we are all animals. The information herein is for reference only, and I bear no liability for misuse or adverse effects (allergy) by using any of these antibiotics. Essentially all of the antibiotics used in veterinary medicine are from human medicine, and most were tested on animals before being used in humans. Although you may have used a particular antibiotic in the past, your body may have developed a sensitivity or allergy to the very same product since then, and you should discontinue any medication if you are exhibiting negative signs (usually a rash).
Everybody gets sick sooner or later. It can be a mild “cold” or upper respiratory infection, or blood poisoning from an infected scratch. In a post-disaster situation, the risk of infection likely will go way up, due to lack of medical care, contamination, stress, poor nutrition, exposure, and reduced hygiene. Even gunshot wounds are possible, or lacerations and broken bones. Having a stock assortment of common antibiotics ready now is a good idea.
Antibiotics don’t change to poison the day after they expire. It has been proven that antibiotics are safe to use for at least five (5) years beyond their expiration date. Don't throw away expired antibiotics or other medications for that matter. They may not be as effective as when they were “fresh,” but they are probably 90+% still active. In a disaster situation they may not be available again for a long time, and you’ll be longing for the Amoxicillin you flushed down the toilet. [JWR Adds: The only exception might be cycline family antibiotics, which have been reported to cause Fanconi Syndrome when they break down. This has been previously discussed in SurvivalBlog.]
Try the “First Choice” medicines; if they aren’t working, try another First Choice, or go to the “Resistant/2nd Choice” column. You won’t have the luxury of doing a culture and sensitivity test to see what is causing your infection and what the best antibiotic is to eliminate it. This will all be trial and error. You have to give an antibiotic at least a three-day try before deciding it’s not working, and even slight improvement is a sign to continue what you’re on. Don’t jump from one antibiotic to another unless symptoms are worsening. Checking body temperature is a good way to judge. If your former fever of 103°F is coming down, it’s a good indicator that things are improving. (Add a digital or “old fashioned” thermometer to your list.)
An abscess generally needs to be drained before it will heal. That means lancing it at some point to “let the corruption out” of the body. Your immune system is trying to throw out the bacteria by killing and consuming it, creating pus, but sometimes the bacteria reproduces faster than the white blood cells can work. That’s where antibiotics help out by interfering with the bacteria’s reproduction or by actually killing the bugs. Often the abscess will rupture by itself, when the skin over the infection breaks down, but you can also get pretty sick before that happens. (Add a half-dozen scalpel blades to that list, too; #10 curved edge for slicing, #11 sharp point for lancing.)