Understanding antibiotic resistance
Understanding antibiotic resistance

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Week 3: How do bacteria become resistant to antibiotics?


In Week 2 you looked at how antibiotics target bacteria, either killing them or preventing their growth. But bacteria are constantly fighting back against this threat to their survival. Antibiotic resistance is the ability of pathogenic bacteria to resist the action of antibiotics so that they survive exposure to antibiotics that would normally kill them or stop their growth (CDC, 2017; PHE, 2017).

You could be forgiven for thinking that antibiotic resistance has been caused by our use, and misuse, of antibiotics. However, as you will see in the following video, bacteria that have not interacted with humans have acquired resistance to many of the antibiotic medicines we use to treat infections.

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Video 1 Antibiotic resistance is a natural bacterial defence mechanism.
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You will return to look at how resistance has evolved and spread in Week 4. In this week, you will focus on how bacteria develop resistance in order to protect themselves from antibiotics. You will start by considering several mechanisms of antibiotic resistance before moving on to look at the differences between intrinsic and acquired antibiotic resistance. You will end the week by returning to the case study to explore the mechanisms responsible for resistance to third generation cephalosporins.

By the end of this week, you should be able to:

  • state what is meant by the term ‘antibiotic resistance’
  • recognise that antibiotic resistance evolved to protect bacteria
  • describe the three main mechanisms of resistance that bacteria have developed to counteract the action of antibiotics
  • give examples of these resistance mechanisms
  • distinguish between intrinsic and acquired antibiotic resistance.

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