Learning Module 1: The science behind AMR

Date: 3 September 2025

The session provided participants with a solid foundation for understanding the scientific aspects of antimicrobial resistance (AMR): fundamental concepts for understanding AMR, scientifically proven measures that patients can take to slow down AMR, and an overview of key research questions on AMR.

The key elements for a good understanding of AMR

Yohann Lacotte, Institut national de la santé et de la recherche médicale (INSERM), Joint Action Antimicrobial Resistance and Healthcare-Associated Infections (EU-JAMRAI 2)

What are antimicrobials? 

Antimicrobials are only designed to combat one type of microbe: bacteria, not viruses, fungi or parasites. 

Not all microbes are harmful. Many play a positive role, such as the bacteria in our intestines that aid digestion. The only problem is pathogenic microbes, those that make us ill. To treat them, we need antimicrobials. 

What is antimicrobial resistance? 

To put it simply, antimicrobial resistance occurs when treatments that were effective against bacteria cease to be effective. 

Microbes are incredibly ingenious and can develop multiple strategies to escape treatment. Examples of resistance mechanisms: 

• Blocking entrance 

• Blocking effect on target 

• Degrading antimicrobials 

• Expelling antimicrobials from the cell 

When pathogenic microbes develop multiple defence strategies at the same time, we may even find ourselves in a situation where the microbes can no longer be treated. 

How is resistance developing? 

Resistance is either natural to certain antimicrobials or can be acquired through random genetic mechanisms, mainly through mutation.  

We have heard a lot about mutation during the COVID-19 pandemic. To understand mutation, we must first understand that all living beings are composed of DNA. DNA is like a Lego castle: to build it correctly, you have to follow instructions that tell you where to place the bricks and in what order. DNA works in much the same way. It is the living instruction manual that gives each cell the instructions it needs to build and maintain the body. Mutations are errors in DNA that cause changes in a living organism. Mutations are like bricks placed in the wrong place. 

Natural resistance: in any given population, there are always a few randomly resistant bacteria. After antibiotic treatment, most sensitive bacteria die and those that survive are mainly the bacteria that were initially resistant. The bacteria then start to grow again and, as the resistant bacteria are now in the majority, they multiply and become the dominant strain. This is why the misuse of antimicrobials is so harmful. 

The positive aspect is that resistant bacteria grow more slowly than sensitive bacteria. Thus, in an environment where there are no antimicrobials, resistance will slowly decrease. 

AMR is not only a problem for human health 

Antimicrobials are used in human and veterinary medicine. Microbes can contaminate humans, animals and environmental ecosystems. Microbes do not respect borders; no country is spared. 

What patients can do to fight AMR – preventive measures  

Diamantis Plachouras, European Centre for Disease Prevention and Control 

Use antibiotics only when necessary 

Most inappropriate uses of antibiotics involve respiratory infections (colds, sore throats, acute bronchitis) caused by viruses. Many bacterial infections are treated by our immune system without the need for antibiotics. Antibiotics do not kill viruses and do not prevent these infections from worsening.  

Antibiotics are not harmless medicines (‘to be on the safe side, let's take an antibiotic’). They can have unpleasant side effects, such as diarrhoea and allergic reactions. They also damage – and this is one of the most underestimated aspects – the beneficial bacteria that live in the human body and cause antibiotic resistance. 

In practice, according to the EU guidelines on the prudent use of antimicrobials in human health, this means that patients should: 

• Inform themselves and seek information from healthcare providers about appropriate antibiotics use; 

• Use antimicrobials only when prescribed; 

• Not use leftover antimicrobials, antimicrobials prescribed for another person, or antimicrobials obtained without a prescription; 

• Return leftover antimicrobials to pharmacies. 

Prevent common infections and protect yourselves an others 

• Hand hygiene: ensure your hands are clean and remind your healthcare provider to do the same. We have recently noticed increased patient involvement in their care in this regard, particularly in reminding healthcare providers to follow appropriate hand hygiene rules.  

• Respiratory hygiene: cover your mouth and nose when coughing; 

• Stay at home when ill; 

• Vaccination: preventing common respiratory infections like flu and pneumonia means less inappropriate antibiotic use and fewer complications that require antibiotics for treatment; 

• Devices (e.g., urinary and vascular catheters are a major risk factor for infections): ask your healthcare professional if you still need the catheter. Patients receiving treatment at home often need these types of devices. 

The European partnership on One Health Antimicrobial Resistance (EUP OHAMR) 

Ulrica Dohnhammar, Swedish Research Council, EUP OHAMR 

Scope of the OHAMR partnership 

• 10 years programme time (2025-2035) 

• 53 partners in 30 countries. AMR requires coordinated efforts in many areas. The OHAMR partnership therefore strives to bring together and strengthen the research system in order to maximise the value of investments. 

• A jointly agreed Strategic Research and Innovation Agenda, for focused action and alignment of priorities.  

• A total budget of approximately 300M Euro. Most of the funds come from participating countries, so we pool them together in order to carry out large-scale research projects.  This will result in research grants being awarded to groups of researchers so that they can further their knowledge on this issue. 

Goals 

The OHAMR partnership aims to: 

• Boost AMR research and innovation, with annual calls for projects;  

• Build capacity in the research sector; 

• Support the best possible use of research data; 

• Make use of research results to achieve impact. To achieve this, we must step outside the world of researchers and collaborate with everyone who contributes to making a difference in AMR: patients, farmers, citizens. 

Task 6.4 – “Involve the community to increase the overall understanding of AMR threats and solutions” – EPF lead 

Foster collaboration, advocacy, and public engagement. For example with: 

• Videos, podcasts, infographics that illustrate new AMR research findings; 

• Targeted messaging for different contexts; 

• Building support for AMR as an issue and strengthening agency for change. 

Help AMR researchers to include end-users in their projects. Everyone knows it is important to involve stakeholders who make a difference in AMR, but how do they know what they need to know?  

• What do researchers need? 

• Developing guidance for researchers – e.g. on how to include patients for example 

• Toolkit for medical researchers 

The goals of this task 6.4 are  

• To bridge the gap between research questions and findings and society’s needs and concerns; 

• To make room in the research for people with lived experience; 
• To strengthen advocacy on AMR threats and solutions.