Impact of probiotics on colonic microflora in patients with colitis: a prospective double blind randomised crossover study.

Background & Aims: The aim of this study was to investigate the spectrum of colonic microflora in patients with colitis and if this could be altered with one month's treatment with synbiotics.

Methods: This was a pilot study in which patients were randomised to either receive a synbiotics preparation for a month and then "crossed over" to receive a placebo, or alternatively to receive the placebo first followed in the second month by synbiotic. Stool samples were collected on entry into the study and then at the end of first and second months respectively. Colonic microflora was measured by terminal restriction fragment length polymorphism technique. Quantitative PCR was used to determine the concentration of individual species.

Results: Sixteen patients completed the study of whom 8 had Crohn's colitis and 8 had ulcerative colitis. Their median age was 62 (IQR 50-65) years. An average of 22 terminal restriction fragments (T-RF's) was identified in each patient. Dice cluster analysis showed that each patient had a unique microbial composition which did not change significantly at different time points in the study, irrespective of whether they had probiotics or the placebo. Probiotic organisms were identified in stool samples but did not alter overall spectrum of microflora. In this pilot study we were unable to identify any specific characteristics related to nature of colitis.

Conclusions: This study suggests that there is no difference in colonic microflora between patients with Crohn's or Ulcerative colitis and that the spectrum of bacteria was not altered by synbiotic administration.