The fecal microbiome in diverticulitis and asymptomatic diverticulosis: A case-control study in the US

ObjectiveThe intestinal microbiota are hypothesized to play a role in the pathogenesis of diverticulitis. We compared fecal microbial communities in individuals with diverticulitis to those with uncomplicated diverticulosis. MethodsWe used 16S ribosomal RNA gene sequencing to assess and compare the microbiota composition of fecal samples from 10 patients presenting with acute diverticulitis (cases) and 10 controls with asymptomatic diverticulosis matched on age and sex. ResultsWe found differences in the distribution of relative abundances of bacterial phyla and genera in diverticulitis cases versus diverticulosis controls. At the phyla level, Verrucomicrobia was more abundant on average in diverticulitis cases at the time of diagnosis than in diverticulosis controls (p=0.07). Univariate analysis identified a significant increase in the genera Coriobacteria (p=0.050), Anaerotruncus (0.046), Subdoliganulum (p=0.034), Marvinabryantia (p=0.006), and Akkermansia (p=0.04), and a decrease in Barnesiella (p=0.035) and Coprococcus (p=0.035) in diverticulitis cases at the time of diagnosis compared to diverticulosis controls. However, after correction for multiple comparisons, these differences were no longer significant. Partial least squares discriminant analysis on all microbial genera showed partial separation of diverticulitis cases at diagnosis and diverticulosis controls. The microbial alpha diversity was higher in diverticulitis cases at time of diagnosis vs controls but this was not significant (Shannon diversity index 7.4{+/-}0.6 vs 6.8{+/-}0.7, p=0.08). ConclusionsIndividuals with diverticulitis differ from those with asymptomatic diverticulosis based on components of the fecal microbiome.