Alexander Fleming, best known for his discovery of penicillin in 1928, was a physician and scientist. He trained at the St. Mary's Hospital Medical School in Paddington, London, earning a medical degree in 1906 and a gold medal in bacteriology in 1908. At the close of his studies, he held positions as assistant to Almoth Wright and as a lecturer to the hospital.

Fleming served as lieutenant and, later, as captain in the Royal Army Medical Corps during World War I. His military service was distinguished by a series of practical contributions to wound treatment, including the use of saline solution as an irrigant. In 1909, he was among the first to employ salversan in the treatment of syphilis.

Returning to civilian life in 1919, Fleming resumed his interrupted bacteriological research in the Inoculation Department of St. Mary's Hospital in London. During this period he discovered two important antibacterial substances, lysozyme and penicillin. Although Fleming vigorously pursued clinical applications for the latter, his use of penicillin was limited to the laboratory for more than twenty years. In 1940, it was shown that penicillin could be stabilized and purified, permitting large-scale production of the antibiotic; by 1942, the substance was being manufactured and distributed for clinical use in the United States, Britain and Canada.

Fleming was made a Fellow of the Royal Society in 1943 and knighted the following year.


Dolman, Claude. "Fleming, Alexander." Complete Dictionary of Scientific Biography, vol. 5, Charles Scribner's Sons, 2008. 28-31.

Created 27 January 2017

Last modified 24 February 2023