He spent four years in a shipping office before entering St. Mary's Medical School, London University. He qualified with distinction in 1906 and began research at St. Mary's under Sir Almroth Wright, a pioneer in vaccine therapy. He served throughout World War I as a captain in the Army Medical Corps, being mentioned in dispatches, and in 1918 he returned to St.Mary's. He was elected Professor of the School in 1928 and Emeritus Professor of Bacteriology at the University of London in 1948. He was elected Fellow of the Royal Society in 1943, and knighted in 1944.
Early in his medical life, Fleming became interested in the natural bacterial action of the blood and in antiseptics. He carried out much important work on combating infections during World War I, and in 1922 discovered lysozyme, a natural anti-microbial substance found in the body. In 1928, whilst clearing his cluttered laboratory, he found that mould had grown accidentally on a culture plate which was being used to grow the staphylococci bacteria (which turns wounds septic), and that the mould had created a bacteria-free circle around itself. He was inspired to further experiment and discovered that the mould prevented bacterial growth. It was one of Fleming's colleagues who identified the mould as penicillin. Fleming subsequently tested the penicillin on animals, with no ill effects, and also used it to cure a colleague's eye infection.
After his initial discovery, Fleming did little more than keep a supply of the mould and return to his routine work. It was the scientists Howard Florey and Ernst Chain who developed penicillin further. Florey and Chain were chiefly responsible for the research which led to its success as a drug, although Fleming took most of the credit for the discovery and its subsequent development. At first supplies of penicillin were very limited, but by the end of World War II it was being mass-produced by the American drugs industry, and given to all soldiers before active service. Fleming received the Nobel Peace Prize in 1945, which he shared with Howard Florey and Ernst Chain.
In 1915, Fleming married Sarah Marion McElroy of Killala, Ireland (who died in 1949) and their son became a GP. Fleming married again in 1953, his bride was Dr. Amalia Koutsouri-Voureka, a Greek colleague at St. Mary's. Dr Fleming died on March 11th in 1955 and is buried in St. Paul's Cathedral, London.
