Great Advance in Medicine: Antibiotics     If you've ever gone to the doctor and been put on antibiotics, you probably didn't give the whole process much thought. But when you do, the discovery of antibiotic drugs has made a huge difference in our lives. It's one of the great advances of the 20th century. Penicillin was discovered in 1929 by Alexander Fleming. He was the Nobel Prize for his discovery, which has since saved millions of lives. Ironically, other antibiotics designed to do the same thing are now becoming a concern themselves. Are infections becoming resistant to antibiotic overuse?