What is Penicilin, The Miracle Drug?

Penicillins are a class of antibacterial medications that target a wide variety of microorganisms. They were the first medications of this kind that doctors used. These medicines have saved millions of lives. Penicillin is derived from Penicillium fungi and can be administered orally or via injection. Penicillins are currently routinely used over the world to treat infections and illnesses.


Penicillin-class drugs work by indirectly rupturing bacterial cell walls. They accomplish this by directly targeting peptidoglycans, which play an important structural role in bacterial cells.

Peptidoglycans form a mesh-like structure around the plasma membrane of bacterial cells, strengthening the cell walls and preventing external fluids and particles from entering the cell.

When a bacterium divides, tiny holes form in its cell walls. These gaps are then filled with newly generated peptidoglycans, which help to rebuild the walls.

Penicillins disrupt the protein struts that connect peptidoglycans. This keeps the bacterium from closing the gaps in its cell walls.

Because the surrounding fluid has more water than the bacteria, water rushes through the perforations into the cell, causing the bacterium to burst.


Alexander Fleming is widely credited with discovering penicillins. According to the anecdote, he arrived to his laboratory one day in September 1928 to discover a Petri dish containing Staphylococcus germs with its lid missing.

The dish had become infested with a blue-green mold known as Penicillium notatum. Fleming noticed a distinct ring around the mold that prevented the germs from growing.

Fleming set the wheels in motion for one of the most beneficial medications in medical history when he discovered this mold and recognized its use.

In March 1942, Anne Miller became the first person to successfully undergo penicillin treatment. She almost missed death after contracting a severe infection as a result of a miscarriage.

Although Fleming discovered the first antibiotic, scientists had to undertake a lot of work before penicillins became widely available.

The majority of the work was done by scientists with superior laboratories and a higher understanding of chemistry than Fleming. Howard Florey, Norman Heatley, and Ernst Chain conducted the first comprehensive and concentrated study on the drug.

In his Nobel Prize acceptance address, Fleming warned that abuse of penicillins could eventually lead to bacterial resistance. This has now become a problem.

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Contrary to popular belief, penicillin resistance is caused by bacteria rather than by the individual. 

Bacteria have existed for billions of years. They have been exposed to harsh settings during this time and are hence highly adaptive. They also renew quickly, allowing for rapid genetic alterations across a population.

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There are three common mechanisms in which bacteria might gain penicillin resistance:


Penicillinase : 

Penicillinase is an enzyme that destroys penicillin. This ability can be transmitted across the bacterial community via a tiny ring of DNA, a process known as conjugation. This is the bacterial equivalent of sexual reproduction, in which individual organisms share newly acquired genetic information.

Altered bacterial structure : 

Some bacteria can modify the shape of penicillin-binding proteins in their peptidoglycan wall, preventing penicillins from binding to it.

Penicillin removal :

Other bacteria create methods for exporting penicillin. Bacteria have efflux pumps, which they use to remove chemicals from the cell. The repurposing of some of these pumps may help the cell to dispose of penicillin.