Analysis of bacterial flora in faeces and mucosa of sigmoid colon in patients with ulcerative colitis

Abstract

Objective To explore the difference in bacterial flora between faeces and mucosa of sigmoid colon, the possible role and significance of microbiota alteration in the genesis of ulcerative colitis (UC). Methods Fusobacterium, Enterococcus, Lactobacillus, Bifidobacterium, Bacteroides and Escherichia were selected as target bacteria colonies. The content of six target bacteria colonies in faeces and mucosa of sigmoid colon of 35 UC patients (20 active UC, and 15 UC in remission) and 20 health controls were detected by real-time fluorescent quantitative polymerase chain reaction (RT-PCR). Two independent samples t-test was performed to compare the differences in bacterial flora between faeces and mucosa of sigmoid colon. Variance analysis was used to compare the differences in bacterial flora among health controls group, active stage group and remission stage group. Results In health control group, the contents of Fusobacterium, Bacteroides, Enterococcus and Lactobacillus in faeces ((10.94±0.29), (12.42±0.39), (8.73±0.84), (9.05±0.35), respectively) were higher than those in the mucosa of sigmoid colon ((9.36±0.66), (9.88±0.82), (7.70±1.17) and (7.96±0.68), respectively, t=9.83, 12.51, 3.20 and 6.35, all P 0.05). For UC patients, the contents of Fusobacterium, Bacteroides, Enterococcus, Lactobacillus and Bifidobacterium in faeces ((9.62±1.13), (11.31±0.71), (9.33±0.65), (8.42±0.80) and (8.85±0.73) lg copy/g, respectively) were higher than those in the mucosa of sigmoid colon ((9.00±0.79), (8.80±0.66), (7.46±0.82), (6.82±1.07) and (8.40±0.72) lg copy/g, respectively, t=2.66, 15.28, 10.58, 7.12 and 2.56, all P 0.05). In remission stage group, the contents of Bacteroides fragilis and Bifidobacterium decreased ((9.42±0.48) lg copy/g and (8.87±0.89) lg copy/g, both P 0.05). In both faeces and mucosa of sigmoid colon, the ratios of Bifidobacterium and Enterobacteriaceae (B/E value) in active stage group were less than 1 (0.98±0.13 and 0.84±0.05), which significantly decreased compared with health control group (1.21±0.19, 1.06±0.08; F=12.64, 76.20, both P 0.05). Conclusions The distribution of target bacteria in feces and sigmoid colonis differed between health controls and UC patients. There are obvious changes in fecal and mucosa associated bacterial flora in UC patients especially in active stage compared with healthy controls. Key words: Colitis, ulcerative; Fecal bacterial flora; Mucosa associated bacterial flora; Real-time fluorescent quantitative PCR