Interestingly, Bacteroides fragilis is previously linked to impaired bacterial tolerance handling by CD-associated genetic variation in the genes ATG16L1 and NOD2, while Bacteroides vulgatus is associated with CD pathogenesis and NOD2 host genetic variants.11,103,104 Moreover, an increase in species of the Enterobacteriaceae family, including Escherichia/Shigella species was observed only in patients with CD. This evidence concerns the gene NOD2 and Cowden disease.