In the far past the way that medicine operated was far different than does today. Medicine did not come in pill form and was not distributed from pharmacies. This was the wild west of medicine far before antibiotics existed. In this time herbs ruled and the majority of the medicine used was taken from them. In the this time many cultures starting to warm to the idea of using molds as medicines. Mold was often used to place on infected wounds. It is unlikely though that these people connected to idea of what they were doing, placing mold on wounds, and the reactions that we taking place. This holds significance because it is from molds that we pull the properties for antibiotics.
With the acceptance of germ theory in the early 1900’s the playing field for how we viewed infections completely changed. In the older views there was no way to explain the ways that these infections took place. It was known that people could spread infections but the mechanics of exactly what was happening were unknown.
With the new insight of germs the cause of the illnesses brought a way to isolate these illnesses and test to ways to attack them as well. “The word antibiotic came from the word antibiosis a term coined in 1889 by Louis Pasteur's pupil Paul Vuillemin which means a process by which life could be used to destroy life. More here“ This is Louis Pasteur to the left.
It seemed that a new way had been found to combat these illnesses that had been so devastating to our world since the dawn of time. In 1942 Penicillin is created and starts to change the way that medicine operates. In 1955 Tetracycline is created and becomes the most broadly prescribes antibiotic. With all these changes it seems that as they say the rest is history.
While all these insights have been beneficial to the ways that medicine operates and saved hundreds of thousands of lives our dependencies on these medicines has a negative property as well. Other interesting information on the topic here and here.