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How did we end up here?

You may ask yourself why antibiotic resistance is becoming such a huge problem right now and how it can be a major threat to global health. Some of the many reasons for this are addressed in this section.

Antibiotic resistance is a natural phenomenon

Firstly however, it is important to understand that antibiotic resistance is a natural phenomenon. The pathways to produce antibiotics have been around for millions of years, and many microbes in the environment produce antibiotics naturally. Microbes for example use these molecules for communication and to compete with other organisms in their environment for space and resources.

For as long as there have been antibiotics, there have also been microbes that can survive their action. Long before the introduction of antibiotics as medicines, resistance mechanisms could be found in environmental bacteria and as protective measures in antibiotic-producing microbes. However, antibiotic resistance was not common in pathogenic bacteria.

During the eighty or so years that humans have used antibiotics, antibiotic resistance has become prevalent in environmental and pathogenic bacteria alike. There has been and continues to be a massive use of antibiotics within the health care, veterinary and agricultural sectors, which has created a strong selection pressure for resistant bacteria. Human use of antibiotics has also resulted in an accumulation of these drugs in many environments, where antibiotic resistant bacteria can flourish. This has also resulted in selection and spread of bacteria that are resistant to several different antibiotics.

Video describing antibiotics and the spread of antimicribial resistance, the threat to human health and agriculture and what can be done to take action. Read more on how to take action in What can I do?

Where do resistance genes come from?

It is not fully clear where the antibiotic resistance genes we see in pathogenic bacteria today came from. When we started to use antibiotics on a large scale in medicine and for other applications, we created a selective pressure for resistant bacteria and for the spread of resistance mechanisms between bacteria. In some cases it has been possible to track the origin of the resistance gene/s in pathogens to environmental bacteria, but often this is not possible. Many of the resistance genes observed in pathogens today likely had a different function than providing resistance in the bacterium where it evolved.

Selected Resources

Resource Description
Q&A: Antibiotic resistance: where does it come from and what can we do about it? Journal article that provides a comprehensive overview and detailed answers to the most common questions regarding antibiotic resistance (6 pages with images).
Drivers, Dynamics and Epidemiology of Antimicrobial Resistance in Animal Production Report that explains and discusses the development and spread of antibiotic resistance and its relations with food production (by FAO, 39 pages + references and appendices).
Martínez JL, Baquero F. Emergence and spread of antibiotic resistance: setting a parameter space. Ups J Med Sci [Internet]. 2014 May;119(2):68–77. Available from:
Wall, B.A, Mateus, A, Marshall, L, Pfeiffer, D.U, Lubroth, J, Ormel, H.J, et al. Drivers, Dynamics and Epidemiology of Antimicrobial Resistance in Animal production [Internet]. Food and Agriculture Organization of the United Nations - FAO; 2016 [cited 2017 Feb 15]. Available from:
Food and Agriculture Organization of the United Nations. Reversing the spread of AMR in Zimbabwe [Internet]. 2016 [cited 2017 Mar 10]. 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: