The fecal transplantations of vancomycin-treated mice severely deteriorated colitis in the transplanted tIsc mice compared to those in mice transplanted with mouse feces not treated with vancomycin; they induced colon shortening, myeloperoxidase activity, and infiltration of activated macrophages and dendritic cells (CD11b+/CD11c+ and NF-κB+/CD11c+) into the colon. Here, MPO is linked to colitis.