Alexander Fleming shared the 1945 Nobel Prize in Physiology or Medicine for the discovery of penicillin and its curative effect in infectious diseases.
Fleming observed penicillin in 1928 after a mold contaminated a Staphylococcus culture and inhibited bacterial growth. He identified the mold as Penicillium notatum and named the antibacterial substance penicillin. Fleming’s initial publication described the observation, but he did not turn it into a practical medicine alone.
Howard Florey and Ernst Boris Chain later developed methods for extracting and producing penicillin in useful quantities. Their work helped make large-scale treatment possible during World War II. A common mix-up is to credit Fleming with inventing the entire modern manufacturing process; the Nobel committee honored Fleming’s discovery and Florey and Chain’s development of its therapeutic use.