September 28th 1928: Discovery of penicillin

On this day in 1928, the Scottish scientist Alexander Fleming discovered penicillin. Fleming, an expert in bacteria, had long been searching for a ‘wonder drug’ which would kill bacteria while not harming the human body. He made inroads in 1922 when mucus from his nose dropped on a dish of bacteria and eradicated it, leading to his discovery of lysozyme and intensifying his search for the elusive ‘wonder drug’. In early September 1928, Fleming returned from a family holiday to discover that some of the Petri dishes on his desk at St. Mary’s Hospital had become contaminated. He piled the contaminated dishes in a tray of Lysol to kill the bacteria, and later discovered that mould had grown on one of the dishes which had avoided contact with the disinfectant. The mould had killed the bacteria growing in the dish, and after weeks of experiments to determine what substance in the mould had had this effect, Fleming and his colleagues concluded that it was a Penicillium mould. Alexander Fleming termed the antibacterial agent in the mould penicillin, but, as he was not a chemist, was unable to isolate it for use in humans. In 1940, two Oxford scientists called Ernst Chain and Howard Florey began working on penicillin, building on Fleming’s research, and used new chemical techniques to create a safe antibacterial powder. Thus was born one of the most important medicines in history, and the antibiotic was immediately shipped to the war front to treat bacterial infections. By 1945, 6.8 trillion units of penicillin were being produced in the United States, and that same year Fleming, Chain, and Florey were awarded the Nobel Prize.

“When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionize all medicine by discovering the world’s first antibiotic, or bacteria killer. But I guess that was exactly what I did.”