Disclaimer: Until it is a SHTF situation then we should be using Dr's and Hospitals. This information is for a time when we are not able to utilize healthcare as we have it now!
I just got on Cal Vet Supply and ordered. They have a large selection of antibiotics labeled for aquarium use (pharmaceutical grade though) at great prices. It is definately something we need to keep in our storage for emergency use. They also have diagnostic tools such as urine test strips. 100 test strips are $26.99. That is equivalent to 100 urine tests. Only the specific gravity values would be different for humans than for animals.
I became a RN in 1995. At that time a Dr would many times order a "Urine dip stick" This is now a thing of the past. Now they just have the lab run a UA. A urine dip stick test will tell you many things. It can tell you if the body is spilling over glucose which would be indicative of Diabetes. It can tell you if there is blood in the urine which would be indicative of many problems. It can tell you if there is a UTI (Urinary tract infection) by showing high nitrites or high leukocytes. You of course would need a lab book so that you could tell which abnormal meant what. If you have an dip stick test that is indicative of a UTI, then if you had a microscope and some gram stain and know what certain bacteria look like (cocci, rods, gram negative or positive,etc) you could identify within reason the type of bacteria present and which antibiotic would work best. I would not suggest trying this if you do not have either a medical background or a background in microbiology.
Having a microscope would be handy also to do manual blood counts. This will take some expertise in being able to identify the difference between a white blood cell, a red blood cell, a platelet. You can get a lab book that tells you what the normal values would be.