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Antibiotic resistance

Antibiotics have provided mankind with the means to treat many common bacterial infections efficiently. However, massive use of antibiotics since their introduction as medicines has lead to increased occurrence and spread of bacteria that are resistant to antibiotics.

The rise and spread of resistant bacteria

Antibiotic resistance is the ability of bacteria to protect themselves against the effects of an antibiotic. In the presence of the antibiotic, resistant bacteria will survive (or at least multiply faster than susceptible bacteria) and increase in numbers. From a clinical perspective, resistance means that a bacterium can grow in the antibiotic concentrations reached in the body during standard therapy. Consequently, using that antibiotic for this infection will most likely result in treatment failure.

Bacteria have two alternative pathways to acquire all types of resistance:

  1. Random changes in the bacterial DNA (mutations) may provide resistance by chance
  2. Alternatively, they can receive resistance genes from other bacteria nearby. This process is called horizontal gene transfer.

If a resistance mechanism gives an advantage to the bacterium it may be maintained, and will be passed on to coming generations as the bacterium divides, or be passed along by horizontal transfer. The resistant bacteria can spread via many routes, for example in food, water, by traveling and trade. The basics behind the emergence and spread of antibiotic resistant bacteria are described in more detail in the sub-section that follows. The subject is further explored in How did we end up here?

Selected Resources

Resource Description
Rise of the Superbugs Video. This narrated and animated video explains more about bacteria in general and the problem of antibiotic resistant bacteria in particular (7 min).
What causes antibiotic resistance? Video. This animated TED-Ed video gives an overview of how antibiotics function, how bacteria evolve to resist their action and how selection of resistant bacteria works (5 min). Also available in Spanish.
Superbug Story: Diary Of A Staph Video. Learn about superbugs from a superbug itself! This animated video from CDDEP explains how bacteria develop resistance to antibiotics and eventually turn into superbugs that are resistant to many antibiotics (5 min).
Lecture: Bacteria, antibiotics and antibiotic resistance (PDF, 5MB) Slideshow. A basic introductory lecture to antibiotics and antibiotic resistance from ReAct (PowerPoint slides, PDF version).
Q&A: Antibiotic resistance: where does it come from and what can we do about it Journal article Q&A that provides a comprehensive overview and detailed answers to the most common questions regarding antibiotic resistance.
Antimicrobial resistance: Fact sheet N°194 Fact sheet from WHO that highlights key consequences of antibiotic resistance, why it is a global concern and what drives the development and spread of resistant bacteria.
Antibiotic resistance has a language problem Journal article discussing the use of correct terminology when talking about antimicrobial resistance.
AMR dictionary Online dictionary that covers all the commonly used terms and phrases related to antimicrobial resistance. Available in several languages including English, French, Spanish and Malayalam.
AMR Dictionary - Dictionary [Internet]. [cited 2020 Nov 25]. Available from:
CDDEP. Superbug Story: Diary Of A Staph [Internet]. 2017. Available from:
Mendelson M, Balasegaram M, Jinks T, Pulcini C, Sharland M. Antibiotic resistance has a language problem. Nature. 2017 May 3;545(7652):23–5.
World Health Organization - WHO. Antimicrobial resistance: Fact sheet N°194 [Internet]. WHO. [cited 2015 Feb 23]. Available from:
ReAct. Lecture: Bacteria, antibiotics and antibiotic resistance - PDF [Internet]. 2015 [cited 2016 Jan 11]. Available from:
PBS Digital Studios. Superbugs: The Empire Strikes Bacteria [Internet]. 2015. Available from:
Wright GD. Q&A: Antibiotic resistance: where does it come from and what can we do about it? BMC Biology [Internet]. 2010 [cited 2014 Oct 14];8(1):123. Available from:
What causes antibiotic resistance? - Kevin Wu [Internet]. 2014 [cited 2014 Oct 2]. Available from: