The initial step of pathogenic bacterial infection in the host is adhesion to and invasion into intestinal epithelial cells; therefore, the anti-adhesion and anti-invasion ability of E. faecium WEFA23 and its mutant strain with OTC deficiency (E. faecium WEFA23 otc−/−) against L. monocytogenes in intestinal epithelial cells Caco-2 was detected. The gene discussed is OTC; the disease is bacterial infectious disease.