FLEMING, SIR ALEXANDER

born Aug. 6, 1881, Lochfield, Ayr, Scot. died March 11, 1955, London, Eng. Sir Alexander Fleming Scottish bacteriologist whose discovery of penicillin (1928) prepared the way for the highly effective practice of antibiotic therapy for infectious diseases. Fleming shared the Nobel Prize for Physiology or Medicine in 1945 with Ernst Boris Chain and Howard Walter Florey, who both (from 1939) carried Fleming's basic discovery further in the isolation, purification, testing, and quantity production of penicillin. After taking his degree at St. Mary's Hospital Medical School, London University (1906), Fleming conducted experiments to discover antibacterial substances that would be nontoxic to human tissues. He continued his research while serving with distinction in the Royal Army Medical Corps in World War I. In 1918 he returned to research and teaching at St. Mary's; he became Hunterian professor (1919) and Arris and Gale lecturer (1928) at the Royal College of Surgeons. In 1921 Fleming identified and isolated lysozyme, an enzyme found in certain animal tissues and secretions, such as tears and saliva, that exhibits antibiotic activity. While working with Staphyloccus bacteria in 1928, Fleming noticed a bacteria-free circle around a mold growth (spores of Penicillium notatum) that was contaminating a culture of the staphylococci. Investigating, he found a substance in the mold that prevented growth of the bacteria even when it was diluted 800 times. He called it penicillin. Fleming found that penicillin is nontoxic but that it inhibits the growth of many types of disease-causing bacteria. He was aware of the significance of his discovery, but he lacked the necessary chemical means to isolate and identify the active compound involved. He was thus unable to obtain a sufficient quantity of penicillin for use on humans. It was not until 12 years later, during World War II, that the pressing need for new antibacterial drugs provided the impetus for Chain and Florey's active development of penicillin. Fleming was elected a fellow of the Royal Society in 1943 and knighted in 1944. Additional reading Two biographies are Laurence James Ludovici, Fleming, Discoverer of Penicillin (1952); and Gwyn Macfarlane, Alexander Fleming, the Man and the Myth (1984).