Bacterial Swarmers Exhibit a Protective Response to Intestinal Stress

Bacterial swarming, a collective movement on a surface, in contrast to sessile biofilms, has rarely been associated with human pathophysiology in health and disease. Here, we report for the first time that bacterial swarmers are associated with protection against intestinal inflammation in a murine model of acute colitis. We show, the presence of bacterial swarmers is highly predictive of intestinal stress in mice, pigs, and humans. We isolated a novel Enterobacter swarming strain, SM3 from mouse feces. In mice, SM3 and other known commensal swarmers, in contrast to their respective swarming-deficient but swimming-competent isogenic strains, demonstrated significant protection from intestinal inflammation. Treatment with SM3 in colitic mice also paralleled a significant reduction in luminal oxygen concentration and enrichment of beneficial anaerobes.  Overall, our work identifies a new paradigm in which intestinal stress, allows for the emergence of swarming bacteria, which in turn can protect and heal from intestinal inflammation.