E faecalis worsens experimental colitis in mice colonized with a simplified consortium of resident intestinal bacterial strains. (A) Histologic colitis scores in cecum (C), proximal colon (PC), transverse colon (TC), and distal colon (DC) from Il10-/- mice colonized with the same resident intestinal bacterial strains as in Figure 1 with (Mix + OG1RF) or without (Mix - OG1RF) E faecalis. (B) IL12/23p40 secretion by colon explant cultures from the same mice (n = 6–8 mice/group, data presented as means ± SD, ∗P < .05 Mix + OG1RF vs Mix - OG1RF, Student t test).