热博体育

The way in which resistance develops is directly linked to the extent to which bacteria are exposed to antimicrobials. This may be within organisms when humans or farm animals are given antibiotics, or because of the mere existence of antimicrobials in the environment (water, soils, etc). Reducing antibiotic consumption worldwide is therefore a possible lever in the fight against this worrying phenomenon. Limiting the circulation of resistance between hosts and their environment, as per the One Health approach, would be another.

A novel study on the transmission of bacterial resistance

To assess the risk of resistance genes being transmitted between bacteria from different compartments (hosts, environment, etc), a team from 热博体育, working with the Institut Pasteur in Madagascar, conducted a pilot study in the area around Antananarivo. The study used Escherichia coli strains resistant to beta-lactamase antibiotics, which are commonly used to treat both animals and humans in the region, as a model, and sought to detect them in a range of hosts (humans, pigs, chicken, ducks, cattle, etc) and in the environment (drinking and irrigation water).

The resistant bacteria were detected in almost 40% of the samples taken, whether from humans, animals or the environment. By sequencing and analysing the core genomes of 510 resistant Escherichia coli strains, the scientists succeeded in reconstructing the phylogenetic relations between them, identifying the genes that confer antimicrobial resistance, and estimating transmission events.

Multiple resistance, a major risk for health and food safety

Above all, the study revealed the substantial genetic diversity of bacteria within a limited geographical zone. It also served to identify new, previously unknown groups of beta-lactamase-resistant Escherichia coli strains. Those strains had a broad range of resistance genes that gave them a multi-resistant phenotype, which poses a major risk for public health and food safety.

Intense circulation between hosts and the environment

However, the most unexpected result, in clear contrast to previous observations in the global North, was the ease with which resistance seemed to circulate between different hosts and compartments. The researchers revealed that transmission was so frequent that they were unable to distinguish bacteria that may be specific to a given host or environment, in other words that there was no genetic structure.

Dissemination of antimicrobial resistance within the environment

A multitude of research prospects

This study, one of the first on such a scale in the global South, therefore illustrated the need for an integrated approach encompassing human, animal and environmental health to combat a phenomenon as complex as antimicrobial resistance. In-depth knowledge of the various evolutionary mechanisms that lead to the emergence and dissemination of antimicrobial resistance on a global level is vital for building appropriate, effective surveillance and control strategies. In this context, , led by the AVIESAN alliance, in Vietnam under the , and in other places, to validate and fine-tune the results obtained from this pilot study.

This research was funded jointly by the Agence de Santé de l'Océan Indien, the 2018-2020 ERDF Interreg-V TROI project and the L'Oréal-UNESCO grant for Women in Science (2019 Young Talents). It is part of the platform in partnership for research and training.