Antimicrobial resistance

What is antimicrobial resistance?

Antimicrobials include antibiotics, antivirals, antifungals and antiparasitics. They are used to combat micro-organisms that cause infections in humans, animals or plants. They have led to major medical breakthroughs, enabling the treatment of previously incurable diseases and increasing human life expectancy. However, their frequent and sometimes unjustified use (treatment unsuited to the micro-organism responsible for the infection, treatment periods that are too short or too long, unsuitable doses) has contributed to the multiplication of micro-organisms that are resistant to these treatments, via the selection of strains capable of surviving antimicrobials.

What are the consequences of antimicrobial resistance?

Today, numerous micro-organisms are resistant to several different antimicrobials (multidrug resistant). The emergence of this resistance has undermined the effectiveness of treatments for infections caused by the resistant micro-organism.

Some situations have resulted in therapeutic dead-ends, where there are no longer any antibiotics effective against a bacterium.

Resistant micro-organisms can be transmitted from animals to humans, and vice versa. This resistance can spread into the environment and be passed on to other bacteria, viruses, parasites or fungi. It can lead to cross-resistance to other antimicrobials, including between treatments intended for plants and drugs used in human medicine. Combating antimicrobial resistance therefore requires an overall approach, encompassing humans, animals, plants and the environment. This is why action to address antimicrobial resistance needs to be taken as part of a One Health approach.

Why are antibiotics used in animal husbandry?

Antibiotics are mainly used in animal husbandry to treat sick animals. Treatments to prevent the onset of an infectious bacterial disease before the appearance of clinical signs (preventive use called prophylaxis), or administered to a group of animals following the diagnosis of a bacterial infection in one or more of these animals (preventive and curative use called metaphylaxis), are highly regulated. They are only permitted when no other solution is possible to avoid infection of the animals and spread of the bacterium.

Antibiotics are administered on prescription and under veterinary supervision. All uses of antibiotics in animal health are subject to European regulations restricting their use, in order to limit the development of antibiotic resistance.

What legislation governs the use of antimicrobials for pets and livestock?

European Regulation (EU) 2019/6 on veterinary medicinal products, which came into force in January 2022, further strengthens the framework for the administration of antimicrobials to animals:

• extension of the ban on the use of antimicrobials as growth promoters (which already applied to animals produced in the EU) to all animals and animal products imported into the EU,
• mandatory veterinary prescription for veterinary medicines containing antimicrobials, in all European countries,
• restriction on the use of antimicrobial veterinary medicinal products for prophylaxis (administration of a medicinal product to an animal or group of animals before clinical signs of a disease, in order to prevent the occurrence of disease or infection),
• restriction on the use of antimicrobial veterinary medicinal products for metaphylaxis (administration of a medicinal product to a group of animals after a clinical disease has been diagnosed in part of the group),
• a total ban on veterinary use of certain compounds reserved for the treatment of infections in humans, in order to preserve the efficacy of antimicrobials,
• consideration of the risk of emergence of antimicrobial resistance in marketing authorisations.

What is a critical antibiotic?

Certain antibiotics are considered critically important to human health because they are the only ones, or among the few, that can treat serious diseases in humans. This is the case with third- and fourth-generation cephalosporins and fluoroquinolones. Their use is therefore regulated in veterinary medicine and should only be considered as a last resort.

Are antibiotics added to feed?

Since 2006, a European regulation has prohibited the use of antibiotic growth promoters in animal feed. However, antibiotics for therapeutic purposes may be added to feed to facilitate their oral administration to an animal or group of animals. They must be prescribed following a diagnosis by a veterinarian.

How can the spread of antimicrobial resistance in animals be prevented?

To prevent and combat the spread of antimicrobial resistance, certain precautions can be taken:

• Only give antimicrobials to animals under veterinary supervision and in accordance with the prescription
• Only use these medicines when necessary, complying with the recommendations by animal species and the regulatory requirements
• Vaccinate animals to reduce the need for antimicrobials and opt for alternatives to these medicines, if available
• Improve hygiene and animal welfare to avoid infections
• Wash hands before and after touching an animal to avoid the transmission of resistant micro-organisms from animals to humans or between animals

How has the level of animal exposure to antibiotics changed?

Since 2011, the overall exposure of animals to antibiotics has halved (-49% between 2011 and 2024). At the same time, exposure to critical antibiotics has fallen particularly sharply (-95% for newer-generation cephalosporins, -87% for fluoroquinolones and -81% for colistin).

What changes have there been in rates of antibiotic resistance in bacteria taken from animals?

Since 1982, when the monitoring of antibiotic resistance in bacteria that are pathogenic to animals began, resistance rates have fallen by varying degrees depending on the animal sector and the antibiotics in question. The proportion of strains resistant to critical antibiotics has remained low for several years. Multidrug-resistant Escherichia coli bacteria are declining.

What is ANSES's role in combating antimicrobial resistance?

ANSES is the National Reference Laboratory (NRL) for antimicrobial resistance. It also coordinates RESAPATH, the only network of its kind in Europe, for monitoring resistance in pathogenic bacteria of animal origin. In addition, it is responsible for issuing marketing authorisations for veterinary medicines.

ANSES's work therefore includes:

• monitoring and studying the presence of bacterial resistance in animals and in food of animal origin ;
• monitoring the exposure of domestic animals to antimicrobials ;
• assessing the risks of resistance when veterinary medicinal products are placed on the market ;
• participating in European and international reference work on antimicrobial resistance ;
• conducting research to better detect and understand antimicrobial resistance.