Exploring the Human Intestinal Microbiome in Health and Disease

摘要

In this thesis, molecule tools were used to study bacteria inhabiting the gastrointestinal tract of humans. One aim was to determine whether certain lifestyle factors, such as an anthroposophic lifestyle, or living on a farm, had an impact on the bacterial composition in fecal samples collected from 90 children. The bacterial composition was determined by terminal restriction fragment length polymorphism (T-RFLP). Each child had a unique bacterial community, but anthroposophic children had a higher bacterial diversity than farm children. A second aim was to study the bacterial communities in fecal samples and biopsies collected from patients with Chrohn's disease (CD), compared to healthy individuals. Several molecular approaches were used to characterize the microbiota in identical twins, including healthy twins pairs that were discordant (one has CD and one is healthy) or concordant (both have CD). The bacterial profiles of healthy twins were highly similar whereas in twins discordant for CD they were very different. An imbalance in the microbiota was observed in a subset of individuals with CD and was correlated with the ideal disease phenotype (ICD). A reduced diversity of Firicutes, and in particular, a depletion of Faecalibacterium prausnitzii was correlated with ICD. By contrast, there was an increased prevalance and abundance of E. coli in ICD individuals.