Recent evidence has shown that Helicobacter pylori (Hp) infection is strongly associated with dyspepsia (Kim et al., 2017) which is likely related to Hp-induced gastric and duodenal mucosal inflammation and gastric acid secretion impairment (Hall et al., 2003; Vanheel et al., 2014; Burkitt et al., 2017). Recent consensus on functional dyspepsia indicates that Hp status should be determined in every patient with dyspeptic symptoms and Hp-positive patients should receive eradication therapy (Wauters et al., 2021). Data on improvement in dyspeptic symptoms after Hp eradication are controversial. Although the improvement of dyspeptic symptoms has been reported in a minority of cases (Talley, 2016), a meta-analysis found conflicting results on the improvement of dyspepsia after Hp eradication (Du et al., 2016).

The symptomatic improvement obtained with probiotic treatments highlights the possible influence of gastric dysbiosis in dyspepsia (Cremonini et al., 2001; Nakae et al., 2016; Ohtsu et al., 2017; Tziatzios et al., 2020; Wauters et al., 2020). The efficacy of eradication treatment on the improvement of dyspepsia, which is associated with the type of antibiotic used, also suggests a possible role of dysbiosis in the onset and persistence of dyspepsia after Hp eradication (Kim et al., 2017). Indeed, Hp infection could create a microenvironment that facilitates the proliferation of some bacterial species, despite beneficial ones, that often perpetuates after the infection eradication, partially due to irreversible mucosal alterations caused by Hp infection, and that creates a new gastric microenvironment favored by host-related factors (Gomez-Ramirez et al., 2021).

Considering the evidence that Hp infection determines alterations in the composition of gastric microbiota (Nardone and Compare, 2015; Klymiuk et al., 2017; Bruno et al., 2018), several studies have been conducted to understand if probiotics may interact with the gastric microbiota bringing benefits in the clinical management of Hp infection (Westerik et al., 2018; Zagari et al., 2018; Fang et al., 2019; Yuan et al., 2021). To this aim, various types of probiotics have been used in combination with different antibiotic-based therapeutic regimens to determine a possible improvement in eradication rate, tolerability, and compliance. Results from laboratory studies and clinical trials appear to confirm expectations but there is a lack of clarity regarding standardization on probiotic type, dosage, and time of administration (Westerik et al., 2018; Zagari et al., 2018; Fang et al., 2019; Yuan et al., 2021). Several previous studies have evaluated the benefits of Lactobacillus rhamnosus GG (LGG) supplementation in combination with clarithromycin-based treatment regimens, triple therapy, and three-in-one bismuth quadruple therapy (BQT) in terms of eradication rate and tolerability of therapy (Zagari et al., 2018; Fang et al., 2019). LGG is one of the most extensively studied bacteria (Capurso, 2019), with its efficacy both in terms of reducing bacterial load (Do et al., 2021) and improving eradication rate in Hp infection (Zheng et al., 2013; Lü et al., 2016; Chen et al., 2021). In addition, LGG has been successfully used in pediatric functional pathology, demonstrating efficacy also in reducing dyspeptic symptoms (Ding et al., 2019). However, to the best of our knowledge, data on probiotic supplementation to evaluate the improvement of dyspeptic symptoms in eradication therapy are lacking. The aim of the present study was to evaluate the influence of LGG supplementation on BQT in the clinical management of Hp-related infection both in terms of efficacy and tolerability and persistence of post-treatment dyspepsia.

A total of 164 patients with active Hp infection were enrolled, of whom 73.8% (121/164) were women. The overall median age was 56 years (95% CI: 53.1–60.0). Group A, which received only BQT, consisted of 98 patients; group B, which received BQT with LGG supplementation, consisted of 66 patients. Demographic and anamnestic data of the two groups are shown in Table 1. No statistically significant differences were observed either in median age and BMI between the two study groups.

Overall, a total of 27 patients were lost at follow-up, 13 in group A and 14 in group B, with a total drop-out rate resulting in 16.5% (27/164). Therefore, at PP analysis, 137 patients were considered, 85 patients from group A and 52 patients from group B. After eradication assessment, a 6-month follow-up visit was performed to assess the persistence of dyspepsia, with a further drop-out of four patients (Figure 2).

This pilot study focused on the possible beneficial effects of LGG in the clinical-therapeutic management of Hp infection and shows the efficacy of LGG supplementation in inducing the remission of dyspepsia after Hp eradication when given in concomitance with three-in-one BQT therapy. Its efficacy in dyspeptic symptoms control after eradication therapy might have important implications in clinical practice since the actual estimated number needed to treat ranges from 8 to 14 (Sugano et al., 2015). Instead, LGG does not improve eradication rates or side effects during therapy.

Considering overall dyspepsia, LGG supplementation in concomitance with eradication treatment significantly improved dyspeptic symptoms with complete remission in 84% of patients who received antibiotics and LGG therapy compared with 60% of patients who received eradication therapy alone. Of note, BQT eradication therapy alone presented a higher efficacy on the remission of dyspepsia in respect of other eradication treatments (Moayyedi et al., 2005).

Instead, taking into account dyspeptic subtypes, LGG resulted essentially relevant for the PDS subtype, whose disappearance was significantly higher in patients receiving probiotics than in patients treated with BQT eradication therapy alone. As already reported by Tack and Talley (2013), PDS prevalence was higher than EPS subtypes. The high efficacy of LGG on PDS dyspepsia that was found in the present study could be partly influenced by the time length of the follow-up of 6 months since it has been reported that, after Hp eradication, PDS tends to have a short-term improvement in contrast to EPS whose improvement is long term (Xu et al., 2013). The time length of 6 months to assess dyspepsia outcomes is the time it takes for gastritis to recover but it needs to be taken into account that an increase in the duration of follow-up could end up in different LGG efficacies with respect to dyspeptic subtypes.

The efficacy of LGG in improving the remission of dyspepsia is likely to be ascribed to its influence on Hp-related gastric and duodenal dysbiosis (O’Hara and Shanahan, 2006; Bruno et al., 2018; Filardo et al., 2022) and, likely, the specific LGG administration schedule may also have positively affected the improvement of dyspepsia. The choice of initiating LGG supplementation 7 days prior to the start of BQT therapy was based on the rationale that LGG possesses anti-inflammatory and inhibitory properties on Hp activity that can improve eradication rates. The efficacy of LGG has been reported both in terms of reducing bacterial load (Zhou et al., 2008; Do et al., 2021) and improving the eradication rate of Hp infection (Zheng et al., 2013; Lü et al., 2016; Chen et al., 2021). The use of LGG during and in the next 7 days after eradication therapy was based on the principle that extended use of probiotics promotes eubiosis and restoration of normal intestinal flora for longer in order to result in improved symptomatology.

By itself, patients with functional dyspepsia have alterations in the gastric microbiota and, in some cases, treatment with probiotics resulted in the improvement of functional dyspepsia (Nakae et al., 2016; Ohtsu et al., 2017; Wauters et al., 2020). Furthermore, the presence of Hp in the stomach causes the development of different environments for bacterial growth (Hunt et al., 2015) that results more relevant than the alterations induced by hypochlorhydria alone (Parsons et al., 2017; Gomez-Ramirez et al., 2021). The subversion of the gastric microbiota due to Hp infection may be related to the intrinsic properties of the bacterium that can create a hostile environment, making it difficult for the other bacteria to survive, thus allowing the establishment of a condition of gastroduodenal dysbiosis (Bruno et al., 2018; Gomez-Ramirez et al., 2021). In Hp-positive subjects, molecular analyses showed a reduction in biodiversity with the absolute prevalence of Hp, followed by Streptococcus (Klymiuk et al., 2017). The beneficial effects of probiotics may contribute to the restoration of gastric eubiosis and, specifically, the improvement of dyspeptic symptoms obtained with LGG supplementation agrees with its known anti-inflammatory and anti-apoptotic properties exerted on epithelial cells of the gastrointestinal mucosa (Yan and Polk, 2002).

Lactobacillus rhamnosus GG supplementation did not improve the three-in-one BQT eradication rate, as previously reported (Zagari et al., 2018). The positive effects of probiotic supplementation on eradication rates have been reported generally with eradication regimens with lower efficacy rates than BQT (Dang et al., 2014; Fang et al., 2019). Furthermore, LGG supplementation did not reduce gastrointestinal and neurovegetative events occurring during the BQT eradication schedule and the comparative analysis of every single effect indicates that LGG supplementation seems to worsen bismuth-related side effects such as black stools and headaches. Similarly, unfavorable potentiation has already been observed in previous studies using bismuth and LGG in the eradication schedule (Zagari et al., 2018), while LGG supplementation during triple therapy without bismuth reduced the side effects during eradication (Armuzzi et al., 2001).

The main limitation of the present study is that the patient sample is not homogeneously distributed in terms either of the number of patients between the two study groups or in gender distribution. The difference in patient enrollment numbers between the two groups is mainly ascribed to the free choice left to the patients at the time of the first visit to choose between the two therapeutic protocols, in consideration of the increased cost of therapy with probiotic supplementation. Nevertheless, the overall number of enrolled patients with dyspeptic is reliable, considering previous studies (Armuzzi et al., 2001). The female prevalence could be in part due to the higher prevalence of dyspeptic disorders in women, as reported by population studies on functional dyspepsia (Ford et al., 2015). Finally, the efficacy of probiotic administration should have required the presence of a placebo treatment group.

Despite this main limitation of the study, the present results offer promising opportunities to perform a sample size calculation for a future RCT to confirm the present observations.

In conclusion, this study suggests a potential efficacy of LGG supplementation to three-in-one BQT eradication therapy in inducing post-eradication remission of dyspeptic symptoms, suggesting the beneficial effects of probiotics in the restoration of gastric eubiosis. Probiotic supplementation could consequently be proposed as a routine therapeutic line that could have a relevant impact on the clinical management of Hp-related dyspepsia. Anyway, more studies should be performed to obtain a deeper knowledge of probiotic effects on gastric microbiota, with the aim of recommending the association of probiotics with eradication therapy.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The study was approved by the Local Ethical Committee (Code: 6944/2022). The patients/participants provided their written informed consent to participate in this study.

GBr and CS designed and supervised this study. PM, GS, AC, GBe, and AR contributed to the subject recruitment and questionnaire collection. PM and GS wrote the manuscript under the supervision of GBr and CS. All authors revised the manuscript and approved the submitted version.