Clostridioides difficile is the major cause of antimicrobial-associated diarrhoea and responsible for increasing community-acquired infections. Animals represent a reservoir of toxigenic C. difficile strains, which can cause infections in humans.
Clostridioides difficile is the major cause of antimicrobial-associated diarrhoea and responsible for increasing community-acquired infections. Animals represent a reservoir of toxigenic C. difficile strains, which can cause infections in humans. We previously characterized C. difficile strains of 11 ribotypes (RT) isolated from equids (n=26) in Normandy between 2018 and 2021. Here, we first collected clinical strains (n=28) isolated from patients hospitalised in the same region and during the same period and belonging to the same 8 RTs as equine toxigenic strains. The strains were characterized by whole-genome sequencing (WGS) analysis. Pan-, core- and accessory genome analyses were performed, all genomes shared 23% of genes (core-genome), while accessory genes accounted for 77% of the pan-genome. Pan-genome analysis revealed an “open” state, indicating substantial genetic variability. We then explored the evolutionary relationships between genomes according to isolate origin or RT by core-genome multilocus sequence typing (cgMLST). We identified related strains (with no differences in cgMLST): two strains had been isolated from equids on the same farms, while the other two had been isolated from equids on different farms. We also found two closely related genomes of RT 126 and RT 078 (3 alleles) between an equid and a patient. All our results indicate i) transmission within each host population, particularly within two farms in the case of equids, and ii) sharing of related strains between human and equine populations, suggesting direct or indirect interspecies transmission and highlighting the importance of a One Health approach to C. difficile surveillance.