Impact of deoxycholate on Clostridioides difficile growth, toxin production, and sporulation.

PURPOSE: Bile acids play an important role in Clostridioides difficile life cycle. Deoxycholate (DCA), one of the most abundant secondary bile acids, is known to inhibit vegetative growth and toxin production. However, limited data are available on the role of DCA on C. difficile sporulation. Here, we investigated the phenotypic and genotypic impact of DCA on the growth, toxin production, and sporulation of C. difficile. METHODOLOGY: Four genetically divergent C. difficile strains were cultured in nutrient-rich broth with and without DCA at various concentrations, and growth activity was evaluated for each strain. Cytotoxicity assays using culture supernatants from cells grown in nutrient-rich broth with and without 0.01% DCA were conducted. Sporulation efficiency was determined using sporulation media with and without 0.01% DCA. Transcript levels of tcdB and spo0A were analyzed using quantitative reverse-transcription polymerase chain reaction. RESULTS: We found that DCA led to growth reduction in a dose-depended manner and regulated toxin production by repressing tcdB expression during vegetative growth. To our knowledge, we have also provided the first evidence that DCA reduces C. difficile sporulation efficiency through the downregulation of spo0A expression during the sporulation stage. CONCLUSIONS: DCA modulates C. difficile sporulation, vegetative growth, and toxin production.

Draft Genome Sequence of a Clostridioides difficile Sequence Type 97 Strain Belonging to Hypervirulent Clade 2.

Clostridioides difficile hypervirulent clade 2 lineages are the major lineages responsible for the outbreaks in North America and Europe. However, the genome sequences of Japanese isolates are scarcely available. Herein, we report the draft genome sequence of C. difficile strain TMD0138 sequence type 97 (ST97), belonging to hypervirulent clade 2, isolated in Japan.

Hypervirulent clade 2, ribotype 019/sequence type 67 Clostridioides difficile strain from Japan.

BACKGROUND: Clostridioides difficile ribotype (RT) 019/sequence type (ST) 67 strains belong to a hypervirulent lineage closely related to RT027/ST1; however, limited data are available for hypervirulent clade 2 lineages in Japan. Herein, we report the draft genome of a C. difficile strain B18-123 belonging to clade 2, RT019/ST67 for the first time in Japan. RESULTS: The pathogenicity locus carried by B18-123 (19.6 kb) showed higher homology (97.29% nucleotide identity) with strain R20291 (RT027/ST1) than the reference strain 630 (RT012/ST54), and B18-123 harbored 8-nucleotide substitutions in tcdC. However, it did not contain an 18-base pair (bp) deletion or a single-bp deletion at position 117 in tcdC, which was identified in the previous strain R20291. A cytotoxicity assay revealed similar cytotoxicity levels between strains B18-123 and ATCC BAA-1870 (RT027/ST1). The B18-123 strain was found to be susceptible to metronidazole and vancomycin. CONCLUSION: Our findings contribute to the further understanding of the characteristics of hypervirulent clade 2 including RT019/ST67 lineages.