BACKGROUND

Proton pump inhibitors (PPIs) and potassium-competitive acid blockers (PCABs) have been reported to alter the gut microbiota. However, the relationship between these alterations and stool properties remains unclear. This study aimed to examine changes in the gut microbiota, stool consistency, and subjective symptoms related to defecation after antacid treatment.

METHODS

Patients who received PPI or PCAB for 6 weeks following endoscopic submucosal dissection for upper gastrointestinal cancers between August 2017 and June 2020 were recruited. Fecal samples were analyzed using amplicon sequencing. Stool consistency and defecation-related symptoms were evaluated using the Bristol Stool Scale (BSS) and Constipation Assessment Scale, respectively.

RESULTS

Forty participants (PPI group, n = 20; PCAB group, n = 20) were enrolled in this study. The BSS was significantly lower after PCAB treatment (p = 0.044). The Chao-1 index significantly increased after PCAB treatment (p < 0.01). The PPI group had increased Streptococcus and Veillonella after treatment, whereas the PCAB group had significantly increased Lactobacillus and Akkermansia, in addition to Streptococcus. The genus Blautia was significantly reduced in the PCAB group following treatment. The group with reduced BSS had significantly lower abundance of Bifidobacterium, Faecalibacterium, and Coprococcus before PCAB treatment. In patients with constipation symptoms, Streptococcus and Lactobacillus significantly increased after PCAB treatment.

CONCLUSIONS

The incidence of constipation increased following PCAB treatment. The observed alterations in specific oral commensal bacteria and butylate-producing bacteria differed between the PCAB and PPI groups and may have contributed to the development of abnormal stool properties.