Characteristics of microbiomes of the saliva, duodenal bulb, and descending portion of superficial nonampullary duodenal epithelial tumors

Introduction Nonampullary duodenal epithelial tumors are rare, but their prevalence is increasing. Various gastrointestinal cancers have been associated with microbiomes. We evaluated the characteristics of the salivary and duodenal microbiomes of patients with nonampullary duodenal epithelial tumors. Methods Saliva and biopsy samples from the duodenal bulb and descending portion were obtained from 15 patients with nonampullary duodenal epithelial tumors and 10 controls. Next-generation sequencing was performed to identify bacteria for comparison. Results Saliva samples had higher Amplicon Sequence Variants (ASVs) and more observed species than duodenal samples. Saliva samples from patients with nonampullary duodenal epithelial tumor were dominated by Bacteroidetes and Prevotella, whereas Proteobacteria and Neisseria were dominant in the control samples. The relative abundance of bacteria was higher in patients with nonampullary duodenal epithelial tumors. Most bacteria were classified as bacteria of oral origin. Oribacterium and Stomatobaculum were significantly higher in the saliva, duodenal bulb, and descending portion of patients with nonampullary duodenal epithelial tumors. Conclusion Patients with nonampullary duodenal epithelial tumors had different salivary and duodenal microbiomes than controls. Bacteria types differed between groups at each site, and most bacteria of oral origin were more abundant in patients with nonampullary duodenal epithelial tumors.