Alexander Fleming

Sir Alexander Fleming was a Scottish physician and microbiologist who revolutionized modern medicine.

He is best known for discovering penicillin, which was the world's first antibiotic substance. This discovery provided a way to cure many infectious diseases that were previously deadly. For his work, Fleming shared the 1945 Nobel Prize in Physiology or Medicine with Howard Florey and Ernst Chain. His scientific achievements earned him a knighthood in 1944 and a place on Time magazine's list of the 100 Most Important People of the 20th century.

Fleming's journey into microbiology began with his education and early military service. Born on 6 August 1881, at Lochfield farm in Scotland, he eventually moved to London to study. He earned his MBBS degree from St Mary's Hospital Medical School in 1906 with distinction. During World War I, Fleming served as a captain in the Royal Army Medical Corps. He worked in battlefield hospitals on the Western Front in France. There, he witnessed many soldiers die from sepsis caused by infected wounds. He observed that the antiseptics used at the time often made injuries worse. These chemicals worked on the surface but could not reach anaerobic bacteria deep inside wounds.

Before his work with penicillin, Fleming made a significant discovery regarding natural immunity. In late 1921, while studying bacteria culture plates, he noticed a contamination in one of them. He discovered that his own nasal mucus inhibited the growth of the bacteria on the plate. He observed a clear, transparent circle around the mucus, which acted as a killing zone for the bacteria. He named this bactericidal agent lysozyme.

To test this, he used tears from co-workers and even used lemons to induce tears. He found lysozyme in various secretions, including blood, sputum, and egg whites. Although it was effective against small amounts of harmless bacteria, it had limited therapeutic potential for treating serious diseases. However, it was the first antimicrobial protein discovered as part of our innate immunity.

Fleming's most famous discovery occurred by chance in September 1928. He had been investigating the properties of staphylococci, a type of bacteria. Before leaving for a family holiday, he left several culture plates on a laboratory bench.

Upon his return on 3 September 1928, he noticed that one culture had been contaminated with a fungus. He observed that the colonies of staphylococci immediately surrounding the fungus had been destroyed. In contrast, the colonies farther away remained normal. He famously remarked, "That's funny." This observation led him to identify the mould as belonging to the genus Penicillium.

Fleming worked to understand how this mould could kill bacteria. He grew the mould in a pure culture and found that the culture broth contained an antibacterial substance. He initially referred to this substance as "mould juice" or "the inhibitor." On 7 March 1929, he officially named it penicillin.

He discovered that the substance was highly effective against many Gram-positive pathogens. These included bacteria that cause scarlet fever, pneumonia, meningitis, and diphtheria. It also affected Neisseria gonorrhoeae, which is a Gram-negative bacterium. However, it did not affect Gram-negative bacteria like those causing typhoid fever. This specific range of effectiveness helped define how antibiotics interact with different types of germs.

Scientific history shows that the specific mould was later identified with more precision. While Fleming suspected it was Penicillium chrysogenum, a colleague named Charles J. La Touche identified it as P. rubrum. Later research corrected these names, and the mould was eventually officially accepted as Penicillium rubens. The source of the contamination was later traced back to a room directly below Fleming's laboratory. This accidental event changed the course of medical history by introducing the era of antibiotics.

The laboratory where these discoveries happened is now preserved as the Alexander Fleming Laboratory Museum.

Fleming's legacy is seen in the massive impact penicillin had on global health. His work is often described as the single greatest victory ever achieved over disease. Because of the ability to treat infections, many previously fatal conditions became manageable. Beyond his laboratory work, Fleming was highly respected in his home country. In 2002, he was included in a BBC poll of the 100 Greatest Britons. He was also voted the third greatest Scot in a 2009 opinion poll.

His life remains a testament to the power of careful observation and scientific curiosity.