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Antibiotics

What are antibiotics and where do they come from?
This article offers and overview of the origin and applications of antibiotics.

Key terms

termmeaning
infectioninvasion of organism by disease-causing microorganism
antibioticsubstance that inhibits growth of or kills bacteria
antibiotic resistanceability of bacteria to remain unaffected by antibiotics

An introduction to antibiotics

The image below shows the life expectancy in different parts of the world over a few hundred years. Can you spot the point of time at which something interesting happens?
Image credit: "Period life expectancy at birth" by ReAct; (Sources: Riley (2005), Clio Infra (2015), UN Population Division (2019)); CC BY 4.0.
As you might have noticed, life expectancy started to dramatically increase towards the late 1800s/early 1900s. One of the main reasons for this is that fewer people were dying due to infectious diseases. The reason for that? The discovery of antibiotics!
If you've ever had an ear or throat infection, chances are that your doctor prescribed you some antibiotics. Before the discovery of antibiotics, these infections could become so severe that they killed people. Once scientists figured out how to use antibiotics, the probability of dying from such infections reduced dramatically (as seen in the above image).
Read on to find out more about where antibiotics come from, and how they help fight infection.
test your understanding 1
How do antibiotics help increase life expectancy?
Choose 1 answer:

What are antibiotics and where do they come from?

Antibiotics are substances that can prevent the growth of some microorganisms. The word itself literally translates to 'against life'. The image below is a picture of a bacterial growth being inhibited on a culture dish by antibiotics.
The fine horizontal lines are rows of bacterial colonies. The small black circles are paper disks soaked with antibiotics, around which clear zones can be seen. These clear zones do not contain bacteria, because the antibiotics prevented their growth.
Here's where things get interesting - they are produced by microorganisms! Certain fungi and bacteria can make several types of antibiotics. In the case of fungi, these substances help protect them against infection. The first ever antibiotic was
, which are a type of fungus. But most of the antibiotics that we use today actually come from a type of soil bacteria called Streptomyces.
test your understanding 2
Which of the following is an example of an antibiotic?
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How do antibiotics work?

Different types, or classes, of antibiotics work in different ways. The common mechanism usually involves the antibiotic entering the bacterial cell and then getting in the way of one or more process inside it. This can lead either to the death of the bacterium, or delay or prevent it from replicating.
For example, one type of antibiotic interferes with the production of bacterial cell walls. This makes the bacterial cell leaky, allowing water to it until it swells and eventually bursts, killing the bacterium.
Another class of antibiotics can stop the bacterium from creating RNA, which brings its entire cellular machinery to a stop - leading to its death.
Antibiotics that do not kill bacteria usually inhibit protein synthesis or DNA replication. This makes it hard for the bacterium to replicate, thus interfering with their growth.

Antibiotic resistance

A word of warning - bacteria can evolve very quickly and the excessive use of antibiotics (especially when not required) can lead to antibiotic resistance. In these cases, the bacteria are either less or no longer affected by antibiotics, and become 'super bugs' that are hard to treat successfully.
test your understanding 3
Which of the following are ways in which antibiotics can prevent bacterial growth?
Choose 2 answers:

test your understanding 4
Why is antibiotic resistance a bad things?
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Want to join the conversation?

  • sneak peak green style avatar for user G. Tarun
    Should we even use or create antibiotics? Is the evidence clear that bacterial infections ought to be cured with effort, and aren't as natural as natural selection? Sorry for this question, but I'm asking with an open mind, to know the truth. I'm not defending any stance, and I myself know antibiotics are lifesaving.
    (9 votes)
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    • stelly orange style avatar for user madhav48719
      Fantastic, antibiotics serves as greatest weapon that helps to fight against bacterias, natural and artificials are now variations with us even after resseliences that they may develop but we would have alternative sollutions as in natural artificials too , numorous variations could be made by biotech buddy ,so technicAAlly we are one step ahead ,,
      (2 votes)
  • hopper cool style avatar for user A
    This was a good artical
    (4 votes)
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  • blobby green style avatar for user aliza.konain.15
    Who else is studying for the health exam
    (1 vote)
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