The faecal flora of patients with Crohn's disease.

The faecal flora of patients with Crohn's disease was compared with that of healthy subjects. In patients with terminal ileitis, numbers of anaerobic gram-negative and coccoid rods (species of Eubacterium and peptostreptococcus) were higher than in the controls whereas anaerobic gram-positive rods and cocci and aerobes occurred in normal numbers. The composition of the flora was neither influenced by duration of the disease nor by ileocaecal resection. In healthy subjects and patients, a chemically defined diet induced only slight changes in the flora. Thus, the flora in terminal ileitis although stable was permanently abnormal. In the patients with Crohn's colitis, abnormally low numbers of anaerobes were found in patients with severe, bloody diarrhoea while aerobic counts were normal. The flora in patients with mild colitis was similar to that in terminal ileitis. It is suggested that the abnormal flora composition might be an expression of the genetic predisposition to Crohn's disease.