The first antibiotic discovered by Alexander Fleming in 1928 was penicillin.
Fleming identified penicillin while working at St Mary’s Hospital in London. After returning to his laboratory in September 1928, he noticed that a blue-green Penicillium mould had contaminated a culture plate of Staphylococcus bacteria. A clear area surrounded the mould because the bacteria were not growing there, suggesting that the fungus released a bacteria-killing substance.
Fleming named that substance penicillin and published his findings in 1929. He recognized its medical potential, but isolating and producing it in useful quantities proved difficult. Researchers at the University of Oxford, including Howard Florey and Ernst Chain, later developed methods to purify and mass-produce the drug. Large-scale production during World War II transformed treatment for bacterial infections.
Penicillin is often confused with streptomycin, which was discovered later, in 1943. Insulin is a hormone used to regulate blood sugar, while aspirin is a pain-relieving and anti-inflammatory drug. Fleming, Florey, and Chain shared the 1945 Nobel Prize in Physiology or Medicine for the discovery and therapeutic development of penicillin.