The History of Alexander Fleming and Penicillin


The advent of penicillin, a group of antibiotics that fight bacterial infections, is often attributed to a Scottish medical professional and researcher named Alexander Fleming.[1] Despite the fact that he was unable to stabilize penicillin, researchers at Oxford University were able to do so, setting the stage for the mass production of such antibiotics, as well as the administration of these antibiotics to help treat bacterial infections.[2] However, since bacteria evolve rapidly, some strains have, over some time, developed resistance to these antibiotics, which is a problem that researchers are continually facing today.[3]

Alexander Fleming Biography:

Born in 1881 in Scotland, Alexander Fleming was a doctor and bacteriologist credited with the discovery of penicillin. As a doctor, he learned medicine in London, practicing at the University of London.[1][4] He also had the honor of serving in World War I as part of the Army Medical Corps, and worked to treat injured British soldiers in the war.[1] Throughout his lifetime and due to his pioneers in the fields of medicine and bacteriology, he received various awards, including knighthood in 1944 and a Nobel Prize in Medicine in 1945.[1][4] Although he died in March of 1955, Fleming’s discoveries remain important in modern-day healthcare and research.

Discovery of Penicillin:

As many scientific breakthroughs occur, Alexander Fleming discovered penicillin primarily by accident! After a vacation in 1928, Fleming returned to his lab and found that there was a zone of “no growth” on an agar plate around a fungus, in which bacteria was not growing.[5] He was able to isolate and identify the area as part of the genus Penicillium, and found that this particular area had antibacterial effects on various gram-positive strains of bacteria.[5] Although Fleming was able to extract penicillin, it was very unstable.[2][5]
At Oxford University, Ernst Chain and Howard Florey were able to turn unstable penicillin into the form of a drug.[2] Due to the amount of clinical trials needed, they designed a fermentation vessel to easily save space and renew the penicillin mold’s broth.[2] Eventually, many other scientists contributed in the perfection of penicillin in time for the drug to be administered in 1941 on Albert Alexander, in order to help him fight off a fatal bacterial infection. Despite his miraculous recovery, he died due to the fact that the drug eventually ran out.[2]

Implications of Penicillin Discovery:

Especially during World War II, Penicillin was used to reduce the number of deaths of soldiers in the militaries of both the United States and Great Britain.[6] It was also during this time that countries began to mass produce penicillin, lowering its cost and increasing its reach.[6] However, as time passed by, an increasing number of bacterial strains were reported to show resistance to penicillin, triggering several penicillin treatments unhelpful.[3] Resistance to penicillin can evolve in bacterial strains relatively quickly due to bacteria’s reproduction rate; this fact is making researchers and doctors harder to stay on track with the resistance genes appearing.[3]
Even though the accidental discovery of penicillin by Alexander Fleming seemed remarkable during the mid-1900s, today, people are realizing the negative impacts of antibiotic resistance. With each new antibiotic drug developed, bacteria can quickly evolve to resist these drugs, which is why it is important for people not to take antibiotics unless absolutely necessary to fight off an infection.


  1. BBC. “History – Alexander Fleming.” BBC. BBC, 2014.
  2. American Chemical Society. “Alexander Fleming Discovery and Development of Penicillin – Landmark.” American Chemical Society. American Chemical Society, 2020.
  3. Centers for Disease Control and Prevention. “About Antibiotic Resistance.” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, March 13, 2020.
  4. Science History Institute. (2020, April 10). Alexander Fleming. Retrieved September 19, 2020, from
  5. Centers for Disease Control and Prevention. (2017). The Discovery of Penicillin-New Insights After More Than 75 Years of Clinical Use – Volume 23, Number 5-May 2017 – Emerging Infectious Diseases journal – CDC. Retrieved September 19, 2020, from
  6. Healio. (2008). Penicillin: An accidental discovery changed the course of medicine. Retrieved September 19, 2020, from

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