Oral microbiome alterations of healthy volunteers with proton pump inhibitor

Background and Aim Acid suppressive agents including proton pump inhibitors (PPIs) are used as first‐line treatment for various acid‐related gastrointestinal disorders. Although known to profoundly reduce gastric acid production, their influence on inhibition of acid secretion as part of the function of the gastrointestinal tract microbiome remains to be elucidated. The aim of the present study was to examine the effects of PPI usage on oral and gut microbiota in healthy volunteers. Methods Ten healthy adult volunteers receiving no medications were enrolled. We obtained fecal, saliva, and periodontal pocket fluid samples from the subjects before and after 4 weeks of once daily administrations of 20‐mg esomeprazole. The effects of PPI administration on bacterial communities were investigated using a 16S rRNA gene sequencing method. Results Species richness (alpha diversity) was significantly different among the salivary, periodontal pocket, and fecal samples. Furthermore, the measurements for UniFrac distances, despite inter‐individual variations (beta diversity), of the microbiota structure of saliva and periodontal pocket and feces samples were clearly separated from each other. The salivary samples showed significant differences between alpha and beta diversity measurements before and after administration of the PPI for 4 weeks. Meanwhile, taxon‐based analysis indicated that PPI administration raised the ratio of Streptococcus organisms in fecal samples, suggesting a potentially unfavorable effect leading to gut microbiota alteration. Moreover, alterations of the microbiota in the oral carriage microbiome along with bacterial overgrowth (Streptococcus) and decreases in distinct bacterial species (Neisseria and Veillonella) were observed. Conclusions These results suggest that PPIs cause both oral and gut microbiota alterations.