Historical figure · Pearson Edexcel International GCSE revision on Incandio

Alexander Fleming

Discoverer of Penicillin · Bacteriologist · 1881–1955

The bacteriologist who noticed a stray mould killing bacteria on a discarded plate and so discovered penicillin — and who warned, from the first, that misusing it would breed resistant germs.

Defend these ideas against Fleming

Incandio is a free revision platform for the Pearson Edexcel International GCSE, and on it a topic counts as mastered only once you have learned it, proved it in questions, taught it back and defended it against the person with the strongest claim on it. Alexander Fleming is that person for 2 topics on the course:

• Penicillin: Fleming, Florey and Chain — History · Changes in medicine, c1848–c1948
• Natural Selection and Antibiotic Resistance — Biology

Who was Fleming?

Alexander Fleming was born on an Ayrshire farm and worked at St Mary's Hospital, London, where he first found lysozyme, a mild antibacterial in tears and saliva. In 1928, returning from holiday, he noticed that a discarded culture plate had been contaminated by a Penicillium mould, and that the bacteria around it had been killed. He identified the 'mould juice' — penicillin — and published, but he could not purify enough to prove it as a medicine, and the finding languished. A decade later, Howard Florey and Ernst Chain at Oxford turned Fleming's observation into the first true antibiotic, and the three shared the Nobel Prize in 1945. In his Nobel lecture Fleming cautioned that careless use of penicillin would let bacteria become resistant — a warning that proved prophetic.

Major achievements

• Discovered penicillin in 1928 from a chance mould contamination
• Earlier discovered lysozyme, a natural antibacterial enzyme
• Shared the 1945 Nobel Prize in Physiology or Medicine
• Warned, presciently, of antibiotic resistance from misuse
• Helped open the antibiotic age that has saved countless lives

Life in brief

• 1881 — Born in Ayrshire: On a Scottish farm.
• 1906 — Joins St Mary's: Begins bacteriology under Almroth Wright.
• 1923 — Discovers lysozyme: A natural antibacterial in bodily fluids.
• 1928 — Discovers penicillin: Notices a mould killing bacteria on a stray plate.
• 1945 — Nobel Prize: Shared with Florey and Chain.
• 1955 — Dies: Of a heart attack, in London.

Explore the life of Fleming — five chapters

1. From an Ayrshire Farm to Paddington — An inheritance, and a water polo match
2. Antiseptics That Killed the Patient — Wartime wounds, and a discovery from his own nose
3. September 1928 — A holiday, an untidy bench, and a mould from downstairs
4. The Oxford Team — Florey, Chain, Heatley and a policeman named Albert Alexander
5. The Warning — What he said in Stockholm in 1945

Read the five-chapter life of Alexander Fleming →

Where Fleming appears in your course

Alexander Fleming has a genuine claim on 7 lessons of the Pearson Edexcel International GCSE science course built into Incandio. Six of them:

• Bacteria, Viruses and Pathogens — Biology: This lesson's hardest idea is that bacteria and viruses are fundamentally different kinds of thing. Fleming's penicillin is the proof in practice: it attacks the bacterial cell wall, which a virus does not have — and he warned about resistance decades before it became a crisis.
• Enzymes: Catalysts With a Shape — Biology: Six years before penicillin, Fleming discovered lysozyme — an enzyme in tears and mucus that breaks down bacterial cell walls. It is a working example of enzyme specificity doing a job in the body, and of how an accident becomes a discovery only if someone notices.
• Digestive Enzymes and Bile — Biology: In 1922, long before the mould, Fleming discovered lysozyme — an enzyme present in tears, saliva and mucus that destroys bacterial cell walls — after a drop from his own running nose landed on a culture plate. It is a real enzyme, found in a digestive secretion, discovered by noticing something odd, which makes him a first-hand witness to what this lesson describes.
• Anaerobic Respiration — Biology: Fleming's whole working method was to grow microorganisms under controlled conditions and identify them by what appeared around them — a cleared ring, a colour change, a substance they had released. This lesson asks you to do the same thing in miniature: limewater turning milky and a flask warming up are products by which respiration is detected rather than seen.
• How Mutations Affect Proteins — Biology: The rare beneficial mutation described on this page is not an abstraction, and Fleming saw the consequence coming before anyone else. In his 1945 Nobel lecture he warned that bacteria exposed to too little penicillin would become resistant to it, and that a careless person could pass a resistant strain to someone else. He was describing exactly what this page sets up: a random mutation producing a protein an antibiotic cannot bind to, in an organism reproducing fast enough for the rare to become common. The next lesson is what happened next.
• Natural Selection and Antibiotic Resistance — Biology: Fleming noticed in 1928 that a mould contaminating one of his plates had killed the bacteria around it, and he named the substance penicillin. What makes him the right figure for this page is what he said afterwards. In his Nobel lecture in 1945 he warned that exposing bacteria to too little penicillin would make them resistant, and described exactly how a careless patient could pass a resistant strain to someone else. He was applying the argument on this page to his own discovery, and everything he predicted has happened.

Debate Fleming in the Agora

Reading is the start. On Incandio an idea counts as mastered only once you have argued it against the person with the strongest claim on it, in structured rounds marked against published descriptors.

• Question the Discoverer — “Fleming's 1928 observation was the decisive step in the development of penicillin.”

Begin

• Start a conversation with Fleming — a dramatised, historically grounded AI portrayal
• Read the Historical Brief
• Explore the life of Fleming — five chapters
• Find your course · Meet all 280 figures