Modern Medicine: Penicillin and Surgery

By the early twentieth century, doctors could identify the germs that caused disease, thanks to Germ Theory, but they still had few ways to kill them inside the body. Ehrlich's magic bullets worked against only a handful of diseases.

The breakthrough came by chance. In 1928, the Scottish scientist Alexander Fleming returned from holiday to his untidy London laboratory. He noticed that a mould, called Penicillium, had grown on a dish of bacteria he had left out — and around the mould, the bacteria had been killed.

Fleming realised the mould produced a substance that destroyed bacteria. He named it penicillin and published his findings.

Why chance matters here: Fleming did not set out to find penicillin. A stray mould spore, an untidy lab, and his sharp observation combined by accident. But chance alone was not enough — it took his trained eye to notice what mattered.

Crucially, Fleming could not find a way to produce penicillin in large amounts or purify it, so it seemed useless as a medicine. His discovery was largely forgotten for about ten years.

Penicillin became a life-saving drug only when two more scientists — and a war — got involved.

In the late 1930s, at Oxford, Howard Florey and Ernst Chain rediscovered Fleming's research. They purified penicillin and, in 1941, tested it on a patient, who improved dramatically before the small supply ran out. They had proved it worked, but they still could not make enough.

The Second World War changed everything. Wounded soldiers were dying from infected wounds, so a drug that killed infection was urgently needed.

Contribution	Person / factor	Detail
Discovery	Fleming (1928)	Noticed penicillin killed bacteria
Development	Florey & Chain (late 1930s–1941)	Purified penicillin and proved it cured patients
Mass production	War & governments (WWII)	US and UK funded factories to make penicillin in bulk

Because Britain was stretched by war, Florey travelled to the USA, where the government and drug companies funded mass production. By the D-Day landings in June 1944, there was enough penicillin to treat all the Allied wounded. War had turned a forgotten curiosity into the world's first mass-produced antibiotic.

Penicillin's success launched the modern pharmaceutical industry. Drug companies grew huge, developing many more antibiotics and other medicines, tested and mass-produced on an industrial scale. Modern medicine could now cure bacterial infections that had killed for centuries.

But this progress created a new problem: antibiotic resistance.

• Antibiotics kill most bacteria, but a few naturally survive.
• These survivors reproduce, passing on their resistance.
• Over time, whole strains of bacteria evolve that antibiotics can no longer kill.

Overuse and misuse of antibiotics — prescribing them for illnesses they cannot treat, or patients not finishing a course — have speeded this up. Resistant infections such as MRSA are difficult to treat, and (as of the mid-2020s) antibiotic resistance is regarded as one of the most serious threats to global health.

Modern treatment of disease is not only scientific and pharmaceutical. Alongside mainstream medicine, alternative and complementary treatments have persisted and grown in popularity — herbal remedies, acupuncture, homeopathy and osteopathy among them. Some patients turn to them for chronic conditions, for gentler side effects, or out of distrust of drug companies. Doctors point out that most lack the rigorous scientific trials of licensed medicines, so their place in modern healthcare remains debated.

Frame this as a current, ongoing issue. Progress is not a straight line: the very drugs that saved millions are becoming less effective, and scientists are in a continuing race to develop new ones.

Alongside drugs, surgery was transformed in the twentieth century, and war was a repeated driving force. The huge numbers of wounded soldiers gave surgeons the need — and, grimly, the opportunity — to develop new techniques.

Development	Context	Significance
Blood transfusions	WWI	Discovery of blood groups and ways to store blood let surgeons replace lost blood
X-rays	WWI (Röntgen discovered them 1895)	Let surgeons locate bullets and shrapnel and see broken bones
Plastic surgery	WWI and WWII	Skin grafts and facial reconstruction for badly burned or wounded soldiers

The First World War in particular pushed forward blood transfusions and the use of X-rays (discovered by Röntgen in 1895), while facial injuries drove the growth of plastic surgery. The Second World War advanced burns treatment and skin grafts further.

War worked as a factor in two ways: it created urgent need, and governments provided money and organisation to meet it.

After the world wars, new science and technology continued to transform surgery, allowing operations that would once have been impossible.

• Transplant surgery: the first successful kidney transplant took place in 1954, and the first heart transplant in 1967. Drugs to stop the body rejecting new organs made transplants routine.
• Keyhole (minimally invasive) surgery: using tiny cameras and fine instruments through small cuts, surgeons could operate with far less damage and quicker recovery.
• Lasers and radiation therapy: precise cutting with lasers and the use of radiation to treat cancers became standard tools.

These advances all depended on science and technology — new materials, electronics and drugs — showing how this factor became increasingly important in the twentieth century.

Together with anaesthetics, antiseptics and antibiotics from earlier eras, these developments made modern surgery safe, precise and ambitious in ways unimaginable in 1850.

The AQA essay asks you to weigh factors. Modern medicine shows how they combine and reinforce each other.

Factor	How it drove change
Chance	Fleming's accidental discovery of penicillin (1928)
The individual	Fleming, Florey and Chain
War	WWII drove penicillin's mass production; both wars advanced surgery
Government	Funded mass production and wartime medical research
Science & technology	The pharmaceutical industry; transplants, keyhole surgery, lasers

The penicillin story is the perfect essay example: no single factor explains it. Chance gave Fleming the discovery, individuals developed it, and war and government funding turned it into a mass-produced drug. Strong answers explain how these factors worked together.

1. Giving Fleming all the credit for penicillin

Fleming discovered penicillin in 1928 but could not produce it. Florey and Chain developed it into a usable drug, and war and government funding made mass production possible. Crediting Fleming alone misses most of the story.

2. Ignoring the role of war and chance

Penicillin is AQA's classic multi-factor example. Chance (the stray mould) and war (the wartime demand and funding) are as important as the individuals. Leaving them out caps your mark on a factor essay.

3. Stating antibiotic resistance as a fixed historical fact

Antibiotic resistance is an ongoing, current problem, not a finished event. Frame twenty-first-century issues as continuing and approximate, not as settled history.

4. Confusing the discovery date with the mass-production date

Fleming discovered penicillin in 1928, but it was not mass-produced until the 1940s, driven by WWII. This ten-year gap is exactly the point: discovery and development are different stages.

5. Listing surgical advances without explaining significance

Do not just name blood transfusions, X-rays and transplants. Explain why each mattered and how war or technology drove it. The exam rewards analysis of significance and factors, not lists.