Is Crohns disease contagious?
While a genetic component of Crohn’s disease is well recognized and a growing list of susceptibility genes have been identified, the factors that trigger disease onset have been more elusive. Many have hypothesized that enteric bacteria, both commensal and pathogenic, may be involved, based on the observations that broad-spectrum antibiotics can induce temporary clinical remission in some patients, many patients display evidence of defective immune tolerance to intestinal microflora, and germ-free animals often fail to develop experimental inflammatory bowel disease. In this issue, Sasaki et al. addressed this hypothesis by characterizing invasive bacteria isolated from colon biopsies. Remarkably, nearly all invasive strains isolated from Crohn’s disease patients and nearly half of those from ulcerative colitis patients were E. coli, whereas only 2% of the invasive strains isolated from control subjects were E. coli. When studied in vitro, invasive E. coli isolated from Crohn’s disease
