The Discovery of Penicillin: Medicine's Greatest Accident
In 1928, Alexander Fleming's accidental observation of a mould killing bacteria led to the discovery of penicillin, the antibiotic that would go on to save hundreds of millions of lives.
By Archive Editorial · 1 January 1929
On 3 September 1928, Scottish bacteriologist Alexander Fleming returned from holiday to find that a mould, Penicillium notatum, had contaminated one of his petri dishes — and was killing the surrounding Staphylococcus bacteria.
Rather than discarding the contaminated dish, Fleming investigated further, recognising the extraordinary potential of what he observed. He isolated the mould's antibacterial substance and named it penicillin.
It was not until the 1940s that Howard Florey and Ernst Boris Chain developed methods to purify and mass-produce penicillin, in time for it to treat infected wounds during World War II. Fleming, Florey, and Chain shared the Nobel Prize in Physiology or Medicine in 1945.