Alexander Fleming

Sir Alexander Fleming was a Scottish bacteriologist and Nobel Prize winner, best known for his discovery of penicillin.

Alexander Fleming was born in 1881. He did research work at one of the hospitals in London and became interested in bacterial action and antibacterial drugs. In 1922, during his work on the bacteriology of septic wounds, he discovered lysozyme, a ferment found in many animal tissues and secretions which attacks bacteria. He was already much preoccupied with the problem of discovering anti-bacterial agents that were not toxic or harmful to the living organism.

Fleming discovered penicillin by mistake when he was trying to study Staphylococcus bacteria in 1928. He was running experiments with the bacteria in his laboratory at London's St. Mary's Hospital, and set a laboratory dish containing the bacteria near an open window. Upon returning to the experiment, he found that some mould blown in through the open window onto the dish, contaminating the bacteria.

Instead of throwing away his spoiled experiment, Fleming looked closely at it under his microscope. Surprisingly, he saw not only the mould growing on the bacteria, but a clear zone around the mould. Fleming understood the importance of what had happened and immediately began to study the phenomenon.

He placed some mould on other plates and grew more colonies. By means of numerous experiments on animals he determined that this new substance was not toxic to the tissues and stopped the growth of the most common pathogenic bacteria.

Fleming called this substance penicillin. It is of the same family of moulds that often appear on dry bread.

But many investigations had been carried out before a method of extracting pure penicillin was found. It was also very difficult for Fleming to interest biologists and mould experts in penicillin and to decide the problem of its production.

In 1942 Fleming tried his own first experiment. A friend of his was very ill, dying. After several injections of penicillin the man was cured. It marked the beginning of penicillin treatment.

However, it was not until World War II that penicillin, the first antibiotic, was finally isolated by Howard Florey and Ernst Chain. Fleming, Florey and Chain received the Nobel Prize in Medicine in 1945, for their discovery which revolutionized medicine and led to the development of lifesaving antibiotics.

Fleming wrote numerous papers on bacteriology, immunology and chemotherapy. He was elected professor of the medical 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. He said: “Everywhere I go people thank me for saving their lives. I do not know why they do it. I didn't do anything. Nature makes penicillin. I only found it.”

Fleming died on 11 March 1955.

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