How does Antimicrobial resistance Happen

What is antibiotic resistance?

Antibiotic resistance is the ability of bacteria to protect itself against the effects of an antibiotic medication. It can happen when the bacteria decreases or destroys the effectiveness of antibiotics which can cure and prevent infections. As a result, the bacteria are able to survive and multiply in the presence of antibiotics, causing more harm.

How does antibiotic resistance happen?

Antibiotics kill or hinder the growth of susceptible bacteria. When exposed to antibiotics, sometimes one of the bacteria can survive because it has found a way to counteract or evade the antibiotic attack. Even if one bacterium becomes resistant, it can multiply and replace all the bacteria that were killed. This is called ‘selective pressure’ and it makes the surviving bacteria more likely to be resistant. (3)

There are several ways in which antibiotic resistance can happen. Random ‘mutations’ or changes can occur in the genetic material of the bacteria every time they reproduce and multiply. These changes may enable the bacteria to survive, protecting them from different types of antibiotics.(1) These genetic changes can also be passed on to other bacteria.(2)

Bacteria may develop the ability to counteract or ‘neutralize’ the antibiotic making it harmless. Some bacteria can even rapidly pump out the antibiotic before it can work. There is also a possibility of the bacteria changing their external structure so that there is no way for antibiotic to attach or penetrate inside bacteria.(3)

Adapted from Centers for Disease Control and Prevention.

Source: ANTIMICROBIAL RESISTANCE (AMR) – Dr Rajiv Desai [Internet]. 2016 [cited 14 January 2019]. Available from:


  1. European Centre for Disease Prevention and Control. Factsheet for the general public – Antimicrobial resistance.
    Available at: Accessed 31 December 2018.
  2. Bennett PM. Plasmid encoded antibiotic resistance: Acquisition and transfer of antibiotic resistance genes in bacteria. Br J Pharmacol 2008; 153: S347-S357.
  3. Centers for Disease Control and Prevention. Antibiotic resistance questions and answers.
    Available at: Accessed 31 December 2018.

PP-CPF-IND-0005| 11th January 2019