Abstract Background and Aims Changes to the oral microbiome have been reported in patients with Crohn’s disease (CD). The aim of this study was to determine the characteristics and dynamics of the oral microbiome in children randomized to 1 of 2 nutritional treatments for CD. Methods Participants (n = 54) in this randomized controlled trial (NCT02843100) received the Crohn’s Disease Exclusion Diet (CDED) with either partial enteral nutrition (PEN; n = 28) or exclusive enteral nutrition (EEN; n = 26). The oral microbiome was assessed via swabs from the dorsum of the tongue and the buccal gingiva by 16S rRNA sequencing at 0, 2, 8, 14, 24, and 52 weeks. Results There were no significant differences in primary or clinical outcomes between the 2 groups. Due to the COVID-19 pandemic, sampling by 24 weeks was limited to 34 participants. At week 0, moderate-severe disease activity (Pediatric Crohn’s Disease Activity Index PCDAI 30) was associated with decreased Porphyromonas, Haemophilus, Alloprevotella, Neisseria, and Bergeyella species and increased Actinomyces. As patients entered remission (PCDAI 10), we observed a restoration in the abundance of these taxa. A modified oral dysbiosis index (MODI) was generated, capable of distinguishing mild from moderate-severe disease activity based on microbiome profiles. Dysbiosis decreased as treatment continued and patients entered remission. Patients on CDED exhibited more significant dysbiosis index changes at weeks 8-24, compared with the EEN group. Application of the index across published oral microbiome data sets validated its ability to discriminate health from CD. Conclusion Oral microbiome changes in pediatric CD reflect disease activity and parallel therapeutic response to CDED and EEN over time. Additional validation of the proposed dysbiosis index should be undertaken in adequately powered future studies.
Moran et al. (Sat,) studied this question.