Small intestinal bacterial overgrowth in patients with Crohn's disease is not only associated with a more severe disease, but is also marked by dramatic changes in the gut microbiome

Background
The main mechanisms that protect against small intestinal bacterial overgrowth (SIBO) are compromised in Crohn’s disease (CD). Therefore, SIBO is a relatively common finding in patients with CD with a reported frequency of 17% to 62%. SIBO represents a clinically relevant event in CD that may affect the symptoms and outcomes. Gut microbiota dysbiosis is strongly associated with CD, but effect of SIBO on the colonic microbiome is not so clear. The aim of this study was to characterise the faecal microbiota composition in adult patients with CD, with or without SIBO.
Methods
A pilot comparative study among CD patients with (n = 36) and without (n = 35) SIBO was conducted, with a focus on differences in the gut microbiome. A lactulose hydrogen breath test (LHBT) was used to determine the presence of SIBO. V3-V4 16S rRNA deep amplicon sequencing on the Illumina MiSeq platform with Reagent Kit v3 (600 cycles) was used to analyse faecal microbiota