Alexander Fleming was a Scottish bacteriologist whose accidental discovery of penicillin in 1928 changed the course of human history. Before penicillin, even minor infections could be deadly. A small cut, a sore throat, or a battlefield wound often led to fatal bacterial infections. Hospitals had limited options, and doctors could only hope the body would fight the infection on its own.
But everything changed when Fleming noticed something unusual in his laboratory at St. Mary’s Hospital in London. A mold had contaminated one of his bacterial culture plates—and instead of ruining the experiment, it revealed something remarkable. The mold was killing the surrounding bacteria.
That mold, later identified as Penicillium notatum, produced a substance that would become the world’s first true antibiotic. Penicillin didn’t just treat infections—it revolutionized medicine, surgery, and wartime healthcare. It saved millions of lives during and after World War II and opened the door to modern antibiotics.
Who Was Alexander Fleming?
Alexander Fleming was born in 1881 in Scotland. He studied medicine and became a bacteriologist—someone who studies bacteria and infectious diseases.
He worked at St. Mary’s Hospital Medical School in London, where he researched how bacteria cause disease. Even before penicillin, Fleming was interested in substances that could kill harmful microbes without harming the human body.
He passed away in 1955, but his discovery continues to save lives every single day.
What Is Penicillin?
Penicillin is a type of antibiotic—a medicine that kills or stops the growth of bacteria.
Antibiotics treat bacterial infections such as:
- Pneumonia
- Strep throat
- Wound infections
- Blood infections
- Certain types of meningitis
Before antibiotics, bacterial infections were among the leading causes of death worldwide.
Think of bacteria like tiny invaders attacking the body. Penicillin acts like a shield and weapon, stopping those invaders from multiplying and spreading.
How Was Penicillin Discovered?
In 1928, Fleming returned from vacation to find that one of his petri dishes had been contaminated by mold.
Normally, contamination ruins experiments. But Fleming noticed something extraordinary:
- The bacteria around the mold had died.
- A clear circle formed around the mold.
- The bacteria further away continued growing.
This clear circle is called the zone of inhibition—an area where bacteria cannot grow because of an antibacterial substance.
Fleming realized the mold was producing something that killed bacteria. He named the substance penicillin, after the mold genus Penicillium.
Simple Analogy
Imagine weeds growing on a lawn. Now imagine placing a special chemical in the center that prevents weeds from growing nearby. The clear patch around it would be like the zone of inhibition.
Why Was This Discovery So Important?
Before penicillin:
- Minor cuts could lead to deadly infections.
- Soldiers often died from infected wounds.
- Surgery was risky due to post-operative infections.
- Diseases like pneumonia and syphilis were often fatal.
After penicillin:
- Bacterial infections became treatable.
- Surgery became safer.
- Childbirth survival rates improved.
- War survival rates increased dramatically.
During World War II, penicillin saved countless soldiers’ lives by preventing deadly wound infections.
How Does Penicillin Work?
To understand how penicillin works, we need to understand bacteria.
Step 1: Bacteria Have Cell Walls
Bacteria are single-celled organisms surrounded by a protective cell wall. This wall:
- Maintains their shape
- Protects them
- Prevents them from bursting
Step 2: Penicillin Attacks the Cell Wall
Penicillin interferes with the formation of bacterial cell walls.
Without a strong wall:
- The bacteria become weak
- They burst
- They die
Simple Analogy
Think of bacteria like water balloons. The cell wall is the rubber surface holding the water inside. Penicillin weakens the rubber. Once weakened, the balloon pops.
Penicillin vs. Bacteria vs. Viruses
| Feature | Penicillin | Bacteria | Viruses |
|---|---|---|---|
| Is it alive? | No (medicine) | Yes | Not fully alive |
| Has cell wall? | No | Yes | No |
| Can penicillin kill it? | Not applicable | Yes | No |
| Examples | Drug | Strep throat bacteria | Flu virus |
Important note:
Penicillin does NOT work against viruses. It cannot treat colds or flu.
The Role of Other Scientists
While Fleming discovered penicillin, it was later developed into a usable medicine by:
- Howard Florey
- Ernst Boris Chain
They helped purify and mass-produce penicillin for medical use.
In 1945, Fleming, Florey, and Chain shared the Nobel Prize in Physiology or Medicine for this life-saving work.
Real-Life Impact of Penicillin
1. War Medicine
Before penicillin, infected wounds caused many deaths. During WWII, penicillin drastically reduced mortality.
2. Surgery
Modern surgery depends on infection control. Antibiotics make complex surgeries possible.
3. Childbirth
Before antibiotics, childbirth infections were common and deadly. Penicillin improved maternal survival rates.
4. Everyday Infections
Simple infections that once required hospitalization can now be treated quickly.
Did You Know?
1. Penicillin was discovered by accident—but only because Fleming was observant enough to notice it.2. Early penicillin was so rare that doctors sometimes recycled it from patients’ urine to reuse it.
3. Fleming warned about antibiotic resistance decades before it became a global problem.Antibiotic Resistance: A Modern Challenge
Bacteria can evolve and become resistant to antibiotics.
If antibiotics are:
- Overused
- Misused
- Not completed properly
Bacteria may survive and become stronger.
This is why doctors advise:
- Only take antibiotics when prescribed.
- Finish the full course.
- Never self-medicate.
Timeline of Events
| Year | Event |
|---|---|
| 1928 | Fleming discovers penicillin |
| 1939–1941 | Florey and Chain develop it further |
| 1944 | Mass production during WWII |
| 1945 | Nobel Prize awarded |
Why Penicillin Is Still Relevant Today
Although newer antibiotics exist, penicillin remains widely used. It treats:
- Strep throat
- Scarlet fever
- Rheumatic fever prevention
- Certain skin infections
Its discovery launched the entire antibiotic era.
Without penicillin, modern medicine would look completely different.
FAQs
1. Who discovered penicillin?
Penicillin was discovered by Alexander Fleming in 1928 when he observed mold killing bacteria in a petri dish.
2. Was penicillin really discovered by accident?
Yes. Fleming did not plan the discovery. He noticed mold contamination and carefully studied its effect on bacteria.
3. What type of infections does penicillin treat?
Penicillin treats bacterial infections such as strep throat, pneumonia, and certain wound infections.
4. Why doesn’t penicillin work on viruses?
Viruses do not have cell walls. Since penicillin targets bacterial cell walls, it cannot affect viruses like the flu.
5. When was penicillin widely used?
It became widely used during World War II to treat infected wounds.
6. Who helped develop penicillin into medicine?
Howard Florey and Ernst Boris Chain helped purify and mass-produce penicillin.
7. What award did Fleming receive?
He received the Nobel Prize in Physiology or Medicine.
8. Is penicillin still used today?
Yes. It remains an important antibiotic for treating several bacterial infections.
9. What is antibiotic resistance?
Antibiotic resistance happens when bacteria evolve and no longer respond to antibiotics.
10. Why is penicillin considered revolutionary?
It was the first true antibiotic and changed how doctors treat infections, saving millions of lives.
