Genomic and Phenotypic Diversity of Carbapenemase-producing Escherichia Coli Strains Circulating in Southern France.

Carbapenemase-producing Enterobacteriaceae (CPE) are classified as emerging Highly Resistant Bacteria (eHRB) because they expose infected patients to the risk of treatment failure due to the strains' resistance to last-line β-lactams, carbapenems, and frequent co-resistance to other classes of antibiotics, leading to increased morbidity and mortality. Their high epidemiogenic potential has enabled their global spread. In France, the incidence of Carbapenemase-producing Enterobacteriaceae is rising sharply, both in colonization and in infections. Parallel to this increase, Escherichia coli has become the most common Carbapenemase-producing Enterobacteriaceae (35% of strains in 2024, National Research Committee data), surpassing Klebsiella pneumoniae (24%).

The investigators hypothesize that the increase in the prevalence of carbapenemase-producing Echerichia coli is associated with a diversification of clones, enzymes, and their variants, and may pose a threefold threat: i) the spread of genes encoding carbapenemases within pathogenic extraintestinal Echerichia coli (ExPEC) pathogroups responsible for urinary tract infections and bacteremias, with a high risk of resistance spreading in the community, ii) the silent spread of Echerichia coli strains producing OXA-48 variants with reduced carbapenem hydrolytic activity, OXA-244 and OXA-484, which are not detected or poorly detected by conventionally used screening media and iii) the emergence of New Dehli Metallo-beta-lactamase (NDM) variants with high hydrolytic activity, such as NDM-5, within Echerichia coli clones possessing Penicillin-Binding Proteins (PLPs) with low affinity for antibiotics, leading to very high-level resistance and a therapeutic dead end in infected patients.