Gnotobiotic OMM12 mice support sustained Clostridioides difficile colonization without antibiotic pretreatment

Gnotobiotic OMM12 mice sustain Clostridioides difficile colonization for at least 20 days after oral challenge with CD630Δerm or clinical R20291 (RT027) without antibiotic pretreatment.

• Why it matters: Antibiotic disruption of the microbiota predisposes to CDI, but existing animal models often struggle to study sustained colonization with a defined resident community.
• What they did: OMM12 mice were orally challenged with CD630Δerm or R20291 (RT027) and monitored for 20 days, including weight, intestinal inflammation, microbiota shifts, prophage induction, and day-20 clone whole-genome sequencing.
• The result: Early infection caused transient weight loss, rapid inflammation, and temporary microbiota shifts; by day 20, markers largely resolved and baseline-like composition returned despite continued detection of vegetative cells, spores, and toxins, with no detectable gut-specific genomic adaptation.