Crohn’s disease (CD) is a chronic relapsing illness that may be caused by a dysbiotic microbiome. Anti-Saccharomyces cerevisiae antibody (ASCA) is present in 30-60% of CD patients, although any link with gut microbiota is unknown. Researchers expected that ASCA positive would be associated with a specific microbial status and clinical phenotype. Children with CD (n = 135) and controls without inflammatory bowel illness (n = 45) had ileocolonic mucosal biopsies taken. ASCA status, microbial diversity, and clinical features were all compared. 

For the diagnosis of CD, ASCA was highly specific but not sensitive. ASCA positivity was related to older age (≥10 years), ileocolonic disease, and long-term risk of surgery in CD patients. Microbial richness was comparable across all three groups. Fourteen bacterial species were linked to ASCA-positive individuals with CD, while 14 species were linked to ASCA-negative patients (P < 0.05). Ruminococcus torques and the bacteria Yersinia enterocolitica 61 remained substantially linked with CD ASCA positivity (P = 0.0178) after employing a false discovery rate correction, but Enterobacter cloacae and Faecalibacterium prausnitzii were significantly associated with CD ASCA negative (P = 0.0178 and 0.0342). The gut microbiota makeup of ASCA-positive and ASCA-negative CD patients differs significantly, which may influence the disease’s phenotype.