BACKGROUND:

Debate persists regarding the role of Desulfovibrio subspecies in ulcerative colitis. Combined microscopic and molecular techniques enable this issue to be investigated by allowing precise enumeration of specific bacterial species within the colonic mucous gel. The aim of this study was to combine laser capture microdissection and quantitative polymerase chain reaction to determine Desulfovibrio copy number in crypt-associated mucous gel in health and in acute and chronic ulcerative colitis.

METHODS:

Colonic mucosal biopsies were harvested from healthy controls (n= 19) and patients with acute (n= 10) or chronic (n= 10) ulcerative colitis. Crypt-associated mucous gel was obtained by laser capture microdissection throughout the colon. Pan-bacterial 16S rRNA and Desulfovibrio copy number/mm 2 were obtained by polymerase chain reaction at each locus. Bacterial copy numbers were interrogated for correlation with location and disease activity. Data were evaluated using a combination of ordinary linear methods and linear mixed-effects models to cater for multiple interactions.

RESULTS:

Desulfovibrio positivity was significantly increased in acute and chronic ulcerative colitis at multiple levels within the colon, and after normalization with total bacterial signal, the relative Desulfovibrio load was increased in acute colitis compared with controls. Desulfovibrio counts did not significantly correlate with age, disease duration, or disease activity but interlevel correlations were found in adjacent colonic segments in the healthy control and chronic ulcerative colitis groups.

CONCLUSION:

The presence of Desulfovibrio subspecies is increased in ulcerative colitis and the data presented suggest that these bacteria represent an increased percentage of the colonic microbiome in acute ulcerative colitis.