Landmark medicine - Penicillin

The following information shared is for general reference and discussion only, therefore should not be considered medical advice.

Discovery

When: 1928-1929

Who: Alexander Fleming (and Ernest Duchesne)

Fleming accidentally discovered that penicillium mould inhibits bacterial growth
Duchesne discovered its antibiotic properties a few decades back

Use

To treat certain bacterial infections, such as strep throat and ear infections

1. B-lactam ring (cyclic amide)

Structure:

a four-membered lactam
the shape makes it more reactive and prone to chemical reactions
interferes cell wall synthesis (construction of bacteria cell walls from a polymer called peptidoglycan)
targets penicillin-binding proteins (PBPs) that form the connection between strands of peptidoglycan

2. R-side chain

Structure:

acylamino side chain (RCONH-) - acyl group (R-CO-) is linked to an amino group (-NH-)
target ability can be modified
determines pharmacological properties

3. Thiazolidine ring

Structure:

Alexander Fleming was unable to purify penicillin and produce it in large quantities, so… who did?

*Several other researchers also contributed to the process.

Australian pathologist

German-born British biochemist

English biologist and biochemist

American neurophysiologist and science writer

remains widely used to this day
treats numerous infections that were once severe or even fatal before its discovery
led to the development of other antibiotics
enabled a deeper understanding of bacterial structures

While penicillin and other antibiotics were once miracle drugs, they are no longer the go-solution for all infections. You might be wondering… why?

Sometimes our immune system becomes hypersensitive to the drug- it will mistaken penicillin as a harmful substance or as an infection.

Allergic reactions: Ranging from mild (rashes, hives) to severe and life-threatening ones (anaphylaxis)
Gastrointestinal issues: Nausea, vomiting and diarrhea
Neurological effects: (rare) Seizures from high doses

Sometimes bacteria develop resistance to antibiotics, including penicillin. You may be wondering, how does that develop?

Genetic mutations of bacteria: Changes affect the effectiveness of penicillin
Gene transfer of bacteria: Bacteria can share resistance genes through plasmids
(DNA molecule), causing the rapid spread of resistance
Alteration of penicillin-binding proteins (PBPs): Genetic mutations of bacteria change the binding sites where penicillin attaches to the PBPs, causing difficulty for the antibiotic to inhibit PBPs

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