Antimicrobial resistance monitoring is essential to guide the proper use of antibiotics, and thus reduce the resistance of microorganisms.
ANSES scientists have taken part in several studies showing how this monitoring can be improved, whether by taking into account bacterial species not yet monitored, the diversification of monitoring contexts or harmonization at European level.
Monitoring the level of antibiotic resistance involves sampling bacteria to test their response to different antibiotics. These samples can be taken from healthy animals, that is to say at the slaughterhouse and from meat, or from sick animals, the samples then being taken by the veterinarians taking care of the animals.
Only the surveillance of antimicrobial resistance in healthy animals and on meat is harmonized at European level. Several countries, including France, are also carrying out antimicrobial resistance surveillance in sick animals. ANSES is in charge of these two follow-ups at the French level.
“These systems are complementary,” Explains Jean-Yves Madec, scientific director on antimicrobial resistance at ANSES. “It’s important to compare their results. Sick animals may be on antibiotic treatment while healthy animals are not, so it is expected to find different levels of antimicrobial resistance between these two groups of animals.”
Complementarity of surveillance systems
This comparison was made in a study published in the journal Microorganisms. This focused on monitoring the antibiotic resistance of the bacterium Escherichia coli in four European countries, in particular France and Germany.
The study showed differences in resistance levels according to antibiotics and animal species, but also between countries and according to surveillance contexts. The differences in resistance levels between countries can be explained in part by differences in the use of antibiotics.
Scientists have shown that differences in trends are possible between data from surveillance of healthy and sick animals. Thus, resistance to an antibiotic, nalidixic acid, tends to increase in bacteria collected from sick chickens but to decrease in healthy chickens, whether in France or Germany. This could be related to the fact that pathogenic Escherichia colistrains are more often confronted with the antibiotic, which favors the development of resistance.
Proposal for a new European network
These results support the need for data in both healthy and diseased animals. In another publication, ANSES scientists, along with colleagues from various European institutes, call for the creation of a European surveillance network for antimicrobial resistance in veterinary medicine (EARS-Vet).
Their article offers the basics of this network, detailing the goals it might have. He also underlines that, based on the achievements of national and European antimicrobial resistance surveillance systems, both in animal and human health, creating such a network is realistic. Nevertheless, harmonization remains to be done, the criteria and the species monitored at present differ from one State to another.
Other bacteria could be watched
Surveillance of antibiotic resistance could also be improved by extending it to other bacteria. Currently, only bacteria that can be transmitted from animals to humans, such as Salmonella or Campylobacter or considered a good indicator of the level of general antibiotic resistance, such as Escherichia coli for example, are monitored regularly. However, other bacteria, responsible for diseases causing significant losses in farms and requiring the use of drugs, could also benefit from such monitoring.
In an article published in Frontiers in Veterinary Science, ANSES scientists have shown how the national surveillance network Vigimyc, which identifies cases of infections of ruminants by mycoplasmas, could be coupled with the surveillance of antimicrobial resistance in this group of bacteria. Scientists were able to detect trends in the development of antibiotic resistance in the different species of mycoplasmas sampled as part of the Vigimic network. However, setting up large-scale surveillance would also require harmonization of the monitoring methods and the criteria for interpreting the results.