A possible role of Eubacterium and Peptostreptococcus species in the aetiology of Crohn's disease.

The faecal flora of patients with Crohn's disease has been found to contain higher numbers of anaerobic gram-negative rods and gram-positive coccoid rods than the flora of healthy subjects. In a considerable percentage of sera from patients with Crohn's disease, agglutinating antibodies were found against four strains of the coccoid rods, in contrast to sera from patients with ulcerative colitis, other diseases and healthy subjects. In the present study, coccoid strains C18, Me46 and Me47 were found to activate complement by the alternative pathway. IgG antibodies to strains Me44, C18 and Me47 had opsonic properties but those to strain Me46 failed to induce phagocytosis. The data suggest an inadequate immune defence against strain Me46 in patients with Crohn's disease. The possible role of strain Me46 in the pathogenesis of Crohn's disease is discussed.