Background: Collagenous colitis is clinically characterized by watery diarrhoea and can histologically be diagnosed by a thickening of the subepithelial collagen layer and an inflammatory infiltrate in the lamina propria. So far, the pathogenesis of collagenous colitis and the role of luminal factors remain unclear.
Methods: This clinical pilot investigation was conducted with an open-label design to monitor the clinical effects of EcN on stool frequency and stool consistency in 14 patients (11 female, 3male; age: 58.1 +/- 9.6 years). Due to the open-label protocol EcN was administered at different doses (1 - 6 capsules/day containing 2.5 - 25 x 10 (9) viable bacteria each). Except for two patients who discontinued treatment, therapy duration was at least 4 weeks.
Results: The results indicate a marked clinical response to the oral administration of EcN with a reduction of the stool frequency > or = 50 % in 9/14 (64 %) patients. Stool frequency clearly (p = 0.034) decreased from 7.6 +/- 4.8/day to 3.7 +/- 5.8/day at the end of therapy (between 4 and 18 weeks). Moreover, stool consistency changed in 7/14 patients from watery or slimy to soft (6 pts) and normal (1 pt), respectively.
Conclusion: With respect to the preliminary data from this trial, the probiotic E. coli strain Nissle 1917 (EcN) seems to be of therapeutic clinical benefit in collagenous colitis. This may be explained with the recently shown antagonistic effect of EcN against Yersinia species, since a relevant number of patients suffering from collagenous colitis showed positive titres of serum IgG and IgA antibodies against Yersinia species. Further studies on the effects of EcN on mucosal collagen metabolism and long-term follow-up are warranted.