What antibiotic did Alexander Fleming discover in 1928?

Alexander Fleming discovered penicillin in 1928. The antibiotic was the first widely recognized natural antibacterial drug and transformed the treatment of serious bacterial infections.

Fleming made the observation at St Mary’s Hospital in London after returning to his laboratory in September 1928. One culture plate of Staphylococcus bacteria had been contaminated by a blue-green Penicillium mold. Fleming noticed that bacteria failed to grow around the mold, suggesting that it released a bacteria-killing substance. He later named that substance penicillin.

Fleming’s early work revealed penicillin’s antibacterial potential, but he could not produce it in quantities suitable for medicine. Researchers at Oxford, including Howard Florey, Ernst Chain, Norman Heatley and Edward Abraham, later developed methods to purify and manufacture it. During the Second World War, large-scale production made penicillin available to treat wounded soldiers and civilians.

A common mix-up is crediting Fleming alone with turning penicillin into a practical drug. Fleming discovered it; the Oxford team and industrial partners made mass medical use possible. Fleming, Florey and Chain shared the 1945 Nobel Prize in Physiology or Medicine.