The Discovery of Penicillin: The Accident That Changed the World
In August 1928, bacteriologist Alexander Fleming was working at St. Mary’s Hospital in London when he noticed something unusual. Curious what Fleming discovered and how it changed medicine? Read below.
In August 1928, bacteriologist Alexander Fleming was working at St. Mary’s Hospital in London when he noticed something unusual: a Petri dish filled with staphylococci had accidentally been contaminated by mold. Fleming initially labeled the intruder as Penicillium rubrum, a fungus commonly found on corn and soybeans, when in fact it was Penicillium notatum.
What caught his attention wasn’t the mold itself, but the clear antibacterial “halo” surrounding it. Something in that mold was stopping the bacteria in their tracks. Fleming recognized the antibacterial power of this mysterious substance and named it penicillin. However, he never tested its effects inside a living organism. For the moment, the world-changing potential of his discovery remained untouched.
From Forgotten Observation to Scientific Breakthrough
A decade later, in 1938, scientists Howard Florey and Ernst Chain at Oxford University were studying antibacterial substances, including lysozyme, an enzyme Fleming had discovered back in 1922. During their research, they revisited Fleming’s 1929 paper on penicillin and immediately sensed there was something worth exploring.
By May 1940, the Oxford team had managed to produce enough penicillin to test it on animals. The results were extraordinary. In August that same year, they published their findings in The Lancet, instantly drawing international attention.
By early 1941, the lab had produced enough penicillin to treat six human patients. Some died from complications unrelated to their infections, but those who survived showed just how powerful the new drug could be. The real challenge? Producing enough of it to keep going.
A Wartime Race for the World’s First Antibiotic
With Britain struggling under the weight of World War II, Florey and his colleague Norman Heatley traveled to the United States in 1941 to seek help from American pharmaceutical and chemical companies. They headed to the Northern Regional Research Laboratory (NRRL) in Illinois, which had experience working with Penicillium strains and fermentation. With American support, penicillin production scaled up dramatically.
On September 4, 1942, the BBC broadcast its first radio program about penicillin — Ariel. It explained what penicillin was, how it worked, and why it mattered. Industrial-scale production during World War II soon became one of the great Anglo-American scientific achievements of the era.
Germany also attempted to produce penicillin, hoping to turn it into a practical, mass-produced antibiotic, but failed. By late 1943, penicillin was available not only to the U.S. military but also to civilians. Year after year, its availability continued to grow.
The Mold That Saved Millions
Penicillium notatum, the humble mold behind the discovery, changed the world. This unassuming multicellular fungus made it possible to treat countless infectious diseases that had once been deadly. Penicillin became the world’s first widely accessible antibiotic and opened the door to the entire era of modern antimicrobial medicine.
Although Fleming discovered the mold by chance, it was Florey, Chain, Heatley, and their teams who recognized its true potential and proved that its active compound could kill the lethal bacteria responsible for infection and death. And they did so in the middle of a world war, when resources were scarce and human suffering immense.
This discovery didn’t just save lives. It altered the course of history.
#history #20century #secondworldwar #penicillin #alexanderfleming #bacteria #microbiology #bacteriology #mold #fungus #antibiotic
Sources:
Briones, Cristina, „Penicillium Notatum - The Miracle Mould“, MAAS Magazine, 2018., https://maas.museum/magazine/2018/10/penicillium-notatum-%E2%80%95-the-miracle-mould/
Liebenau, Jonathan, „The British Success with Penicillin“, Social Studies of Science, Vol. 17, No. 1 (Feb., 1987), Sage Publications
Shama, Gilbert; Reinarz, Jonathan, „Allied intelligence reports on wartime German penicillin research and production“, Historical Studies in the Physical and Biological Sciences , Vol. 32, No. 2 (2002), University of California Press
Shama, Gilbert, „Auntibiotics“, British Medical Journal, Vol. 337, No. 7684 (Dec. 20 - 27, 2008), BMJ
Swann, John, Patrick, „The Search for Synthetic Penicillin during World War II“, The British Journal for the History of Science, Vol. 16, No. 2 (Jul., 1983), Cambridge University Press