Bacillus Probiotics With Bismuth Quadruple Therapy for Helicobacter Pylori Infection

Helicobacter pylori (H. pylori) infection affects roughly half of the world's population, making it a very common digestive disease. In developing countries, infection rates are especially high, with 85-95% of the population potentially infected with H. pylori, making this disease a major public health concern. H. pylori mainly infects and lives in the mucous membrane of the stomach lining, enabling it to persist for long periods and lead to chronic infection. Its survival in the stomach's harsh acidity is primarily due to urease, an enzyme that breaks down urea into ammonia, neutralizing the stomach acid. In Vietnam, historically, clarithromycin-based triple therapy achieved eradication rates exceeding 90%. However, rising global antibiotic resistance has reduced its efficacy to below 70%, leading to its removal from first-line recommendations in regions with high resistance. As a result, bismuth-containing quadruple therapy, which includes a proton pump inhibitor (PPI), tetracycline, metronidazole, and bismuth, has become the standard first-line and rescue treatment for H. pylori eradication.

While this regimen is highly effective, yielding eradication rates between 90.4% and 99.3%, it frequently induces significant gastrointestinal adverse effects. Clinical data indicate that 54.1% to 67.0% of patients experience symptoms such as dizziness, nausea, vomiting, diarrhea, black stools, fatigue, and anorexia. Furthermore, the high-dose administration of tetracycline and metronidazole causes severe disruption of the normal gut microbiota (dysbiosis). This dysbiosis is characterized by a marked decrease in beneficial microbial populations, such as Bacteroidetes and Actinobacteria, alongside a concerning overgrowth of opportunistic pathogens, such as Proteobacteria. These severe side effects often lead to poor patient compliance, causing patients to reduce dosages or prematurely discontinue therapy. This lack of adherence, in turn, contributes to treatment failure and exacerbates the increasing global challenge of antibiotic resistance.

The use of spore-forming probiotic strains from the genus Bacillus in Helicobacter pylori eradication regimens has recently garnered considerable attention within the scientific community, yielding promising outcomes in randomized controlled trials (RCTs). Multicenter studies have demonstrated that supplementation with Bacillus clausii alongside antibiotic regimens significantly reduces the incidence of antibiotic-associated diarrhoea (AAD) and other gastrointestinal symptoms, including nausea and a bitter taste. This, in turn, enhances drug tolerance and treatment adherence among patients. Additionally, research on Bacillus subtilis and Bacillus coagulans offers substantial medical evidence concerning their direct and indirect mechanisms of action. In vitro studies indicate that B. subtilis may inhibit H. pylori growth through secretion of natural antimicrobial compounds, particularly amicoumacin A, while other Bacillus-derived bacteriocins and lipopeptides may contribute to broader antimicrobial activity. In contrast, B. coagulans has demonstrated efficacy in modulating local immune responses, reducing inflammatory cytokines, and preserving the integrity of the gastric mucosa against bacterial damage.

Although there is substantial evidence for the effectiveness of Bacillus species, data on their effectiveness in supportive treatment with bismuth-containing quadruple drug regimens remain limited, particularly studies evaluating the simultaneous effects on bacterial eradication, adverse effects, and changes in mucosal immune response and gut microbiota.

Therefore, this study was conducted with two main objectives:

1. To evaluate the rate and severity of adverse effects, as well as treatment compliance of bismuth-containing quadruple drug regimens (BQT) when combined with single-strain (B. clausii - LiveSpo Clausy) or with multi-strain (B. subtilis, B. clausii, B. coagulans - LiveSpo DIA 30) spore probiotics;
2. Evaluate the H. pylori eradication rate along with changes in secretory IgA (sIgA) and gut microbiota before and after H. pylori eradication treatment with the BQT regimen combined with spore-forming probiotics (single-strain, multi-strain Bacillus).

This study is designed as a randomized, double-blind, placebo-controlled trial conducted at the Gastroenterology Department of Tam Anh Hospital. The study population consists of 336 eligible adult patients with confirmed active Helicobacter pylori infection, as determined by standardized diagnostic tests, specifically the 13C-Urea Breath Test. To ensure balanced comparison, participants will be randomly assigned in a 1:1:1 ratio to three parallel groups, with 112 patients in each group. All randomized patients will receive a standard 14-day bismuth-containing quadruple therapy, based on group assignment, patients will receive either a single-strain probiotic (LiveSpo Clausy), a multi-strain probiotic (LiveSpo DIA 30), or a placebo (RO water). To maintain the double-blind design, all adjunctive ampoules are identical in appearance, labelling, and packaging. All groups received the assigned probiotic product at a dose of 3 ampoules per day for 2 weeks. After completing the antibiotic course, participants continued probiotics at two ampoules per day for an additional six weeks.

A structured monitoring protocol will be implemented at specific intervals: Baseline (Week 0), Week 1, Week 2, Week 4, and Week 8. During these visits, standardized questionnaires will assess patient compliance, the incidence of gastrointestinal adverse effects, and overall symptom resolution. Subsequent stool samples will be collected for post-treatment laboratory analyses to quantify Bacillus colonization and track dynamic shifts in the gut microbiota. Finally, the primary clinical endpoint, successful H. pylori eradication, will be objectively confirmed 6 weeks after the completion of the antibiotic therapy.

Expect outcomes:

• Primary Outcome Measures: (i) Antibiotic-Associated Adverse Event Rate and Severity; (ii) Change in Gastrointestinal Symptom Score; (iii) Change in Stool Consistency.
• Secondary Outcome Measures: (i) Medication Adherence via MARS-5; (ii) Pill Count Adherence Rate.
• Exploratory Outcome Measures: (i) H. pylori Eradication Rate; (ii) Change in Faecal Secretory IgA (sIgA) Concentration; (iii) Gut Microbiota Composition and Diversity; (iv) Detection of Probiotic Bacillus Spores in Stool.

Tabular analysis is performed on dichotomous variables using the χ2 test or Fisher's exact test when the expected value of any cell is below five. Continuous variables are compared using either the t-test or the Mann-Whitney test when the data are not normally distributed. Statistical and graphical analyses are conducted using GraphPad Prism v8.4.3 software (GraphPad Software, CA, USA). The significance level for all analyses is set at p < 0.05.