The Discovery of Penicillin

It can be said that the discovery of antibiotics was a real turning point in human history. For the first time, doctors could stop deadly infectious diseases in their tracks! This edition of Throwback Thursday takes a look at not just any antibiotic, but the original antibiotic. That’s right, we’re learning all about penicillin! Let’s find out more…

Who discovered penicillin?

Like many great things, penicillin was discovered by accident. Its discoverer was Dr. Alexander Fleming, Professor of Bacteriology at St. Mary’s Hospital in London. After a summer spent in his homeland of Scotland in 1928, Fleming returned to find a somewhat messy lab bench, which he had not cleaned before his departure.

Upon further examination of some Staphylococcus colonies (bacteria that causes boils, sore throats and abscesses), Fleming spotted a mold, which we now know to be called Penicillium rubens, that had contaminated his Petri dishes. Curious, as any good bacteriologist should be, he placed the dishes under his microscope. To his surprise, the mold had prevented the normal growth of the staphylococci! 

Fleming got to work to grow enough of the mold so that he could experiment further. He found that there was something in Penicillium mold that not only stopped the growth of bacteria, but also could be used to combat certain infectious diseases. 

Dr. Alexander Fleming famously wrote, “When I woke up just after dawn on September 28, 1928, I certainly didn’t plan to revolutionize medicine by discovering the world’s first antibiotic, or bacteria killer… But I guess that’s exactly what I did.” 

The development of penicillin antibiotic 

Development began in 1938, when Dr. Howard Florey and his colleagues decided to unravel the science behind what Fleming called Penicillium’s antibacterial action. Part of the team was biochemist Dr. Ernst Chain. 

Together, they produced crude Penicillium mold culture extracts and successfully experimented on mice. The problem they faced was producing enough pure penicillin to treat people. It took 2,000 liters of mold culture fluid to gather enough pure penicillin to treat a single case of sepsis in a person. 

In 1941, before the United States entered World War II, Florey and colleague Dr. Norman Heatley flew to America. They worked with scientists there to develop a means to mass-produce what would become the “wonder drug”. Here they discovered the fungus Penicillium chrysogeum, thanks to lab assistant Mary Hunt picking up a mouldy cantaloupe at the market. 

The fungus held 200 times the amount of penicillin as the already known species that Fleming had discovered over 10 years prior. They enhanced this species with mutation-causing X-rays and filtration, which resulted in producing 1,000 times as much penicillin as those first batches. 

Where are we now?

Today, we use penicillin as an antibiotic to treat bacterial infections, including ear, chest, throat and skin infections. However, antibiotics aren’t routinely used to treat infections anymore. Many infections stem from viruses, making antibiotics ineffective against them. In addition, the more antibiotics are used to treat trivial conditions, the more likely it is that they will be ineffective when treating more serious conditions. 

Penicillin is still a wonder drug when used only when needed and, of course, if the patient doesn’t have a penicillin allergy! And we can thank Dr. Fleming for being untidy in his lab and not cleaning up before his summer holiday.