Penicillin Is Discovered

Penicillin Is Discovered

Thanks largely in part to his penchant for keeping a messy lab, British bacteriologist and Nobel Laureate Sir Alexander Fleming discovered the world’s most used antibiotic, Penicillin, on this day in history in 1928.

In the summer of 1928, Fleming left his lab in St. Mary’s Hospital to go on a two-week holiday. As usual, he didn’t clean up before he left, leaving bacteria cultures growing in the petri dishes he was studying. When he returned from his vacation, Fleming discovered that many of his petri dishes had grown moldy. As he sorted through them, dunking them into a Lysol bath to kill the bacteria, he noticed something strange about one particular petri dish. The blue-green mold that grew in it seemed to have destroyed the Staphylococcus aureus bacteria that had been growing in the dish. Fleming realised the mold was special.

After discussing the mold with a mycologist, or mold expert C.J. La Touche, Fleming determined the mold to be a Penicillium mold, a type of mold that grows on bread. The mold likely floated up from La Touche’s lab on the floor below, where he was collecting mold for an asthma study. During the next few months, Fleming experimented with the mold and found that it killed a large number of harmful bacteria and yet it was non-toxic to humans. In 1929, Fleming wrote a scientific paper on his discovery, but it garnered little scientific interest and was largely forgotten.

Some 12 years later, during the second year of World War II in 1940, two Oxford University scientists were searching for a way to treat infected battlefield wounds. Howard Florey, an Australian, and Ernst Chain, a German refugee, began experimenting with Fleming’s penicillin. Using a chemical technique, they were able to transform the antibacterial compound in the Penicillium mold into a brown powder that was safe, effective, and had a relatively longer shelf life.

The new drug was needed immediately on the warfront to treat infections and was quickly shipped en masse to army hospitals. Many soldiers who might have otherwise died from simple bacterial infections in minor wounds were saved by the new wonder drug. It also treated diphtheria, gangrene, pneumonia, syphilis, and tuberculosis. By the war’s end, more than 20 chemical companies were manufacturing 650 billion units of penicillin per month to treat soldiers.

In 1945, Fleming, Florey, and Chain were awarded the Nobel Prize in Physiology or Medicine. Upon accepting his award, Fleming dryly noted, “One sometimes finds what one is not looking for.”

More than half a century later, penicillin remains the world’s most used antibiotic and Fleming and his messy lab are still credited for its discovery.

Credit: Alamy
Caption: The original culture plate on which Fleming first observed the growth of penicillin notatum.