What's a SNP between friends: The lineage of Clostridioides difficile R20291 can effect research outcomes

Clostridioides difficile R20291 is the most studied PCR-Ribotype 027 isolate. The two predominant lineages of this hypervirulent strain, however, exhibit substantive phenotypic differences and possess genomes that differ by a small number of nucleotide changes. It is important that the source of R20291 is taken into account in research outcomes. •Two phenotypically distinct lineages of C. difficile R20291 are in circulation.•Affected are gene transfer, motility, sporulation, biofilm and toxin production.•The differences are due to a small number of single nucleotide genomic changes.•These findings underline the importance of appropriately maintaining stock cultures.•The source of R20291 should be stated in any investigation.