Fleming, Alexander (1881–1955)

Scottish bacteriologist who was awarded a Nobel Prize for Physiology or Medicine in 1945 for his discovery of the bactericidal effect of penicillin in 1928. In 1922 he had discovered lysozyme, an antibacterial enzyme present in saliva, nasal secretions, and tears. While studying this, he found an unusual mould growing on a culture dish, which he isolated and grew into a pure culture. This led to his discovery of penicillin, which came into use in 1941. He shared the award with Howard W Florey and Ernst B Chain, whose research had brought widespread realization of the value of penicillin with its isolation and its development as an antibiotic drug.

Fleming was born in Lochfield, Ayrshire, and studied medicine at St Mary's Hospital, London, where he remained in the bacteriology department for his entire career, becoming professor in 1928.

Fleming discovered the antibacterial properties of penicillin, but its purification and concentration was left to Florey and Chain in Oxford. He identified organisms that cause wound infections and showed how cross-infection by streptococci can occur among patients in hospital wards. He also studied the effects of different antiseptics on various kinds of bacteria and on living cells. His interest in chemotherapy led him to introduce Paul Ehrlich's Salvarsan into British medical practice. He was knighted in 1944.