Sir Alexander Fleming

1881-1955

Scottish Bacteriologist

Alexander Fleming discovered penicillin, a "wonder drug" that ushered in the era of antibiotics. This new weapon against bacterial disease offered hope in fighting many infections that could not be treated effectively in the past. Together with Sir Howard Walter Florey (1898-1968) and Ernst Boris Chain (1906-1979), Fleming was awarded the Nobel Prize in 1945. In addition to penicillin, he also discovered lysozyme, an antibacterial agent found in tears and saliva.

Fleming was born on August 6, 1881, on a farm in Lochfield, Ayrshire, Scotland. He began his education in Scotland and then went on to London, where he received his medical degree in 1906 from St. Mary's Hospital Medical School at the University of London. He lectured there until World War I, during which he served in the Army Medical Corps. After the war he returned to St. Mary's, and in 1921 identified lysozyme. He was appointed a professor in 1928.

That same year, Fleming was experimenting with the staphylococcus bacteria, and had the good luck to have one of his culture plates contaminated by a mold called Penicillium notatum. Around the mold, there was a ring in which no bacteria grew. Further experiments confirmed that the effect was due to a substance produced by the mold, and it not only inhibited the growth of many types of bacteria, it killed existing growth. The effect was specific to Penicillium notatum; other molds did not work the same way.

Fleming called the active substance penicillin. He diluted it hundreds of times, and it was still effective. He showed that, unlike harsh antiseptics such as phenol, penicillin did not destroy white blood cells. He injected it into animals without negative effects. He published the results of his experiments in 1929, suggesting that the substance might have therapeutic uses, but the mold extract was too perishable to allow extensive tests. Penicillin was largely neglected for a decade.

In 1939, the sulfanilomide derivatives, or sulfa drugs, were introduced by the Italian pharmacologist Daniel Bovet (1907-1992). Sulfa was effective against streptococcus and other disease-causing bacteria, and saved many lives during World War II. However, it was somewhat toxic, tending to cause kidney damage if not used very carefully. Its promise, coupled with the needs of the war, interested researchers in finding other valuable medicines with fewer toxic effects.

It was at this point that Chain and Florey obtained a sample of Fleming's Penicillium notatum culture. Isolating the active substance, penicillin, they were able to purify it so that it was more stable and produce it in larger quantities. Then they performed clinical trials that demonstrated its effectiveness for use as an antibiotic. Like sulfa, penicillin was employed in what amounted to a massive field trial during World War II.

Honors soon followed for all three men. In addition to the Nobel Prize, Fleming was elected a Fellow of the Royal Society in 1943 and knighted in 1944. In 1948, he became emeritus professor of bacteriology at the University of London. He died in London on March 11, 1955.

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