Alexander Fleming (1881-1955)

Discoveries

Alexander Fleming's discovery of penicillin as an antiseptic, followed by the work of Howard Florey, Ernst Chain and Norman Heatley, led to the development of penicillin as an antibiotic during the early years of the Second World War.

By 1943 penicillin was being used to help treat British, American and allied troops. Following the war, it was developed further and became a powerful weapon in fighting infections and disease.

Penicillin

The discovery of antibiotics is a great milestone in the history of medicine.

Many doctors believe that penicillin is one of the greatest medical advances.

It can treat most forms of killer diseases such as meningitis, pneumonia and diphtheria. Blood poisoning and septic wounds can also be treated effectively.

The discovery of penicillin

In 1928, Fleming was in his laboratory with petri dishes scattered across his workbench, working on the staphylococci group of bacteria. He noticed a mould on one dish which had contained a harmful kind of bacteria. Around this mould there was a clear area where the germs had disappeared.

Fleming was keen to investigate this mould and put it in a dish to observe its growth. The mould was identified as one of a group known as 'Penicillium'. This was named after the Latin word for fine brush – the shape the bacteria resembled.

As Fleming had demonstrated the bacteria killing properties of 'Penicillium notatum', he decided to call his discovery 'penicillin'.

Penicillin developed as an antibiotic

Unable to see progress in this research in the 1930s, Fleming set it aside, but provided mould cultures to anyone who requested them.

In 1940 he learned that Howard Florey, Ernst Chain and Norman Heatley had conducted experiments on his culture and had discovered a method of producing a concentrated penicillin. Their laboratory in Oxford was soon turned into a factory, with the mould grown in containers similar to hospital bedpans.

Florey and Chain later approached drug companies to help with the production of penicillin.

Lysozyme

In 1922 Fleming discovered a way of destroying bacteria.

While lecturing in bacteriology, he found some interesting properties and proved the natural antiseptic value of 'lysozyme'.

When tidying up his usual clutter of test tubes and mouldy culture plates, Fleming noticed something unusual.

One of the plates was covered with golden-yellow colonies of bacteria. However, where a droplet of mucus from Fleming's nose had fallen two weeks earlier there were no bacteria at all. They had been wiped out.

Significance of lysozyme

Fleming went on to prove that many body fluids contain a substance that can dissolve certain bacteria quickly. He named the substance 'lysozyme'. This comes from the words 'lysing' meaning dissolving and 'enzyme' – a class of proteins which catalyse, or enable, chemical reactions.

Lysozyme could potentially kill off some bacteria without harming human cells. Because of this Fleming was keen to find out the significance of this substance and research its properties. Details were published in his article of 1922.

Fleming was unable to extract any great conclusions or convince his colleagues of the significance of the discovery. They regarded it as an interesting but unimportant observation.

Portrait image: © Alexander Fleming Laboratory Museum (Imperial College Healthcare NHS Trust).

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