Discovery of Penicillin, 1928

Episode #3 of the course “Most Important Historical Events of the 20th Century”

Alexander Fleming is credited with the discovery of penicillin in 1928, but it was not introduced to the market until the 1940s. Penicillin is an antibiotic that jump-started the development of a wide range of antibiotics. Its discovery is considered one of the greatest advances in therapeutic medicine.

Before the discovery of penicillin, there was no way to treat infections like rheumatic fever, pneumonia, or gonorrhea. Blood poisoning from something simple like a cut or scratch was a common cause of death before penicillin. Antibiotics like penicillin are produced by fungi and bacteria that are capable of killing or curbing the development of other microbial species. Although this idea may have been around since the ancient Egyptians (who applied moldy bread to infected wounds), it was not developed in a useable way until the 1940s.

Alexander Fleming was a professor of bacteriology at St. Mary’s Hospital in London. He was cleaning out his petri dishes, which he’d left out after a holiday break, when he noticed something odd in one of the bowls. The dish had mold growing on it, and around the mold was a clear liquid. It was as if the mold was secreting something that destroyed or inhibited the growth of the other bacteria in the dish. He attempted to remove the liquid around the mold to isolate it and study it. However, it was very unstable, and he was only able to create solutions that were very difficult to test and manipulate. He published his findings in the British Journal of Experimental Pathology in 1929, but he only made a slight reference to penicillin’s potential medical benefits.

Nonetheless, Fleming’s discovery set the development of penicillin in motion. Several researchers at Oxford University, including Howard Florey and Ernst Chain, were able to develop penicillin into a useful drug in the 1940s.

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