IMHO, based upon observed physician practice patterns in ER and acute care hospital patients:

Find a friendly physician or veterinarian and get a big brown bottle of penicillin or amoxacillin: 500mg caps or tabs in a brown container. store it somewhere cold and dry. Get dosing information from your friendly doc. If allergic to penicillin, or more adventurous and wealthier, get levaquin. Pen and amox are available in generic form: http://www.petcarechoice.com/index.cfm?fuseaction=product.search&product_namefilter=amoxacillin

To anticipate some of the objections:

1) Antibiotics are dangerous in untrained hands: (so are guns, knives,hatchets, ferrocerium rods, fish hooks and scalpels: it is generally asserted that these things have their place in survival planning)

2) People who need antibiotics are going to die anyway: (everybody is going to die anyway. Survival planning and most medical therapy is about delaying the inevitable. Even the DR designed aviation survival kit does not promise eternal life)

3) People treated with these meds in optimal settings suffer side effects, toxicity, and bad clinical outcomes, which would be worse in sub-optimal crisis conditions. (see (2) above)