Baseline Characteristics and Eradication Rates of the Study Population
A total of 144 individuals with H. pylori-positive non-ulcerative dyspepsia were enrolled in this study. These participants were randomly allocated to three treatment groups: SRAC (n = 48), BRAC (n = 48), and RAC (n = 48). Clinical parameters including age, gender, smoking status, and BMI were consistent across all three groups. Eradication rates, assessed through both ITT and PP analyses, revealed a 75% eradication rate for group SRAC in both analyses. In group BRAC, ITT and PP analyses demonstrated eradication rates of 85.42% and 93.18%, respectively, while group RAC displayed rates of 62.5% (ITT) and 65.2% (PP). Two-group comparison tests established significant disparities in eradication rates across the groups (ITT analysis: SRAC vs. BRAC, p = 0.012; BRAC vs. RAC, p = 0.042) (PP analysis: SRAC vs. BRAC, p = 0.009; BRAC vs. RAC, p = 0.021). Notably, group BRAC exhibited a marginally higher eradication rate compared to the other groups. Common adverse events included nausea, abdominal pain, abdominal distension, and diarrhea. The overall incidence of adverse events differed significantly among the three groups (p = 0.018), with a lower frequency of diarrhea observed in group SRAC compared to group BRAC (p = 0.01). Remarkably, patients receiving S. boulardii treatment exhibited an overall reduction in initial dyspepsia symptoms by the end of the treatment period (Table 1).
Comparison of Fecal Microbiome Composition in Saccharomyces boulardii Powder Combined with Triple Therapy between Treatment Groups
For all three groups, fecal samples were subjected to sequencing of variable regions V4-V5 of the 16S rRNA gene using Illumina HiSeq/MiSeq platforms. This approach aimed to assess alterations in the gut microbial community. Operational taxonomic units (OTUs) were utilized to represent results with a 97% homology cutoff value (Fig. 1a). Principal coordinates analysis (PCoA) exhibited distinct clustering of microbiota composition for each group (Fig. 1c-e). A comparison of bacterial diversity before and after treatment revealed a significant diversity shift among the BRAC group (p < 0.05), whereas no significant diversity difference was observed for the SRAC and RAC groups around treatment. Following 14 days of treatment, the BRAC group displayed a more pronounced alteration in gut microbiota compared to the SRAC and RAC groups (p < 0.05), signifying a heightened impact of bismuth quadruple therapy on intestinal microecology. Diversity trends were reflected in Shannon and chao1 index analysis (Fig. 1b), with all treatment groups demonstrating reduced diversity on the 14th day, followed by increased diversity on the 44th day. Lower community richness was observed in the RAC group compared to the other two groups (p < 0.05).
At the phylum level, the relative abundance of dominant taxa identified from sequencing across all three groups is illustrated in Fig. 2a, capturing specific gut microbiota changes. Prior to treatment, no significant variation in phylum levels was observed among the three groups, with Bacteroidota, Firmicutes, Proteobacteria, and Fusobacteria accounting for over 95% (p < 0.05). In the SRAC group, other prevalent bacteria included Actinobacteria, Acidobacteria, Tenericutes, Chloroflexi, Cyanobacteria, and Gemmatimonadetes. In the BRAC group, other notable bacteria encompassed Actinobacteria, Acidobacteria, Chloroflexi, Verrucomicrobia, Synergistetes, and Cyanobacteria. The RAC group exhibited additional dominant bacteria like Actinobacteria, Chloroflexi, Acidobacteria, Verrucomicrobia, Cyanobacteria, and Nitrospirae. Post-treatment, the relative abundance of Firmicutes decreased in the SRAC and BRAC groups, with subsequent recovery trends before treatment by the 44th day. In contrast, the RAC group displayed continuous Firmicutes abundance escalation following the 14th and 44th days of treatment. Changes in Bacteroidota, Proteobacteria, and Fusobacteria before and after treatment followed a similar pattern within each group. Notably, in the SRAC and RAC groups, relative abundance of Bacteroidota, Proteobacteria, and Fusobacteria declined after 14 days of treatment, rebounding after 44 days and reverting to pre-treatment trends. The converse was observed for the BRAC group, where these bacteria increased post-14-day treatment and decreased after 44 days.
At the genus level, variations in relative bacterial community abundance before and after treatment were evident, marked by distinct changes in bacterial genus composition with notable inter-individual differences. Bacteroides emerged as the most prevalent bacterium (Fig. 2b), and further details of intestinal bacteria composition are provided in Fig. 2b. The SRAC group featured beneficial bacteria such as Bacteroides, Faecalibacterium, Prevotella_9, Lachnospiraceae_NK4A136_group, Roseburia, Lachnospira, Lachnoclostridium, and Parabacteroides. After 14 days of treatment, the SRAC group witnessed significant elevation in beneficial bacteria like Proteiniphilum and Anaerofustis (Fig. 3b, p < 0.05), along with a marked decrease in pathogenic bacteria including Helicobacter, Mycobacterium, Dialist, and Sanguibacteroides (Fig. 3b, p < 0.05). By the 44th treatment day, bacterial community abundance experienced a general increase. In the BRAC group, advantageous bacteria encompassed Bacteroides, Faecalibacterium, Prevotella_9, Escherichia-Shigella, Parabacteroides, Lachnoclostridium, and Roseburia. After 14 days of treatment, the BRAC group displayed notable increases in Faecalibacterium and Subdoligranulum (Fig. 3a, p < 0.05). On the 44th treatment day, Bifidobacterium, Collinsella, and Actinomyces showed higher abundances (Fig. 3a, p < 0.01), whereas Roseburia, Lachnospira, and Fusicatenibacters decreased significantly compared to pre-treatment levels (Fig. 3a, p < 0.05). In the RAC group, advantageous bacteria included Bacteroides, Prevotella_9, Fusobacterium, Faecalibacterium, Escherichia-Shigella, Parabacteroides, Roseburia, and Sutterella. Following 14 days of treatment, the RAC group exhibited an increase in beneficial bacteria like Phascolarctobacterium (Fig. 3c, p < 0.05), coupled with a decrease in pathogenic bacteria such as Campylobacter, Streptococcus, Scardovia, Neisseria, and Morganella (Fig. 3c, p < 0.05). By the 44th day of treatment, bacterial community abundance had risen compared to baseline. In summary, diverse treatment regimens yielded distinct impacts on intestinal microecology, with bismuth quadruple therapy displaying a more pronounced short-term interference on gut microbiota.