Alexander Fleming’s discovery of penicillin in 1928 is one of the most significant breakthroughs in medical history, marking the beginning of the antibiotic era.

Fleming, a physician and bacteriologist, noticed that a mold called Penicillium notatum produced a substance that killed a wide range of bacteria. This discovery led to the development of penicillin, the first true antibiotic*, which could effectively treat bacterial infections that were previously fatal, such as pneumonia, sepsis, and gangrene.

The importance of penicillin cannot be overstated, as it revolutionized the treatment of infectious diseases and drastically reduced mortality rates. During World War II, penicillin saved thousands of lives and has since continued to be an integral part of modern medicine, paving the way for the development of other antibiotics and fundamentally changing the treatment of infections.

*Sulfonamide, or "sulfa drugs," were the first widely used antibacterial drugs, beginning with experiments using Prontosil in 1932. Sulfonamides paved the way for the more broadly effective antibiotics like penicillin that forever changed the treatment of infectious diseases.