Antibiotics didn't start to become commonly prescribed until the middle of the twentieth century. Before that, illnesses that nowadays might be wiped out with a 10-day course of antibiotics were often fatal. Ever had strep throat? Imagine dying from it. People did all the time.
Thank you, Alexander Fleming, for discovering penicillin in 1928, and thanks Ernst Chain and Howard Florey, who turned the rough stuff into something we could use to make us well. You deserved that Nobel Prize in Medicine you shared in 1945!