Genomic evolution and virulence association of Clostridioides difficile sequence type 37 (ribotype 017) in China

Clostridioides difficile sequence type (ST) 37 (ribotype 017) is one of the most prevalent genotypes circulating in China. However, its genomic evolution and virulence determinants were rarely explored. Whole-genome sequencing, phylogeographic and phylogenetic analyses were conducted for C. difficile ST37 isolates. The 325 ST37 genomes from six continents, including North America (n = 66), South America (n = 4), Oceania (n = 7), Africa (n = 9), Europe (n = 138) and Asia (n = 101), were clustered into six major lineages, with region-dependent distributions, harbouring an array of antibiotic-resistance genes. The ST37 strains from China were divided into four distinct sublineages, showing five importation times and international sources. Isolates associated with severe infections exhibited significantly higher toxin productions, tcdB mRNA levels, and sporulation capacities (P