Penicillin Discovered

Setting the scene

In 1928, bacterial infections were death sentences—pneumonia killed 30% of patients, strep throat could lead to fatal sepsis, and even minor wounds often became infected and killed. Alexander Fleming, a Scottish bacteriologist at St. Mary's Hospital in London, was studying Staphylococcus bacteria. On September 3, 1928, returning from a two-week vacation, Fleming noticed something odd in a petri dish he had left out—mold had contaminated it, and around the mold, the bacteria had been killed. The mold was Penicillium notatum, a common bread mold.

What happened

Fleming isolated the antibacterial substance, naming it penicillin. He published his findings in the British Journal of Experimental Pathology in 1929, noting penicillin killed many bacteria but was non-toxic to animals. However, Fleming couldn't purify it and lacked the chemistry skills to develop it as a drug. He largely abandoned the work, and penicillin remained a laboratory curiosity for a decade. In 1938, Howard Florey and Ernst Boris Chain at Oxford University, fleeing Nazi Germany, revived Fleming's work. By 1940, they purified penicillin and proved it cured bacterial infections in mice.

Why it still matters

The first human trial in 1941 on Albert Alexander, a policeman dying of sepsis, showed miraculous results—he improved dramatically before the penicillin ran out and he died. Mass production began in 1943 in the US for World War II, with the US producing 2.3 million doses by D-Day in 1944. Penicillin saved countless soldiers and launched the antibiotic revolution. Fleming, Florey, and Chain shared the 1945 Nobel Prize in Physiology or Medicine. Penicillin increased average human lifespan by 23 years and made modern surgery, chemotherapy, and organ transplants possible. It remains one of history's most consequential discoveries, though overuse has created antibiotic-resistant superbugs, threatening to return us to the pre-antibiotic era.

Background

Mass production during WWII made it medically transformative.