Helicobacter pylori, a gram-negative group of bacteria, is one of the most common causes of persistent bacterial infection leading to chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue lymphoma, and gastric cancer (1). The early diagnosis and efficient eradication of H. pylori infections are crucial for gastric cancer prevention (2), which is particularly relevant in populations where the prevalence of H. pylori infection and gastric cancer is high, such as in Asian countries. The prevalence of H. pylori infections in Asia was approximately 55% and gastric cancer cases in this region constituted nearly 75% of global cancer deaths (3, 4). Thailand, a country located in the center of Southeast Asia, has recently seen a decline in its H. pylori eradication efficacy, with the standard triple therapy recommended as a first-line regimen. According to the Thailand consensus in 2015, standard triple therapy was recommended as a first-line regimen because of its simplicity. However, due to the rise in clarithromycin resistance, the efficacy of the 14-day triple therapy has become largely suboptimal, and it is associated with average eradication rates of approximately 80% or less (5). Several strategies, such as the use of potent acid suppressive medication or supplementation with an adjuvant, were reported to improve the eradication rate of this first-line regimen.

Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer health benefits on the host” (6). The addition of certain probiotics to H. pylori eradication regimens was shown to decrease the side effects of antibiotics (e.g., abdominal pain, nausea, and diarrhea), resulting in improved patient adherence and increased eradication rates (5). Moreover, studies have demonstrated that Lactobacillus, the Bifidobacterium species, and Saccharomyces boulardii can provide beneficial therapeutic effects against H. pylori through their modulation of immune responses (7, 8). A recent network meta-analysis reported that Lactobacilli and multi-strain formulations yielded superior eradication rates (9). L. rhamnosus R0011 and L. helveticus R0052 can help to maintain epithelial barrier function, inhibit pathogen adhesion, and downregulate proinflammatory cytokines (10). Compared with different strains of the same species, L. rhamnosus R0011 is less likely than L. rhamnosus GG to cause bacteremia GG due to the absence of spaCBA-encoded pili, which are important adhesins facilitating attachment to the mucosal surface (11). In the present study, we hypothesized that R0011 and R0052 might reduce the severity of H. pylori infection and decrease the gastrointestinal side effects typically associated with H. pylori eradication regimens.

Out of the 160 patients with H. pylori infection who were assessed for eligibility, 70 were excluded and 90 were enrolled in the study and randomly assigned to receive 14-day standard triple therapy with either probiotics or placebo ( Figure 2 ). Baseline demographic characteristics were similar between the groups at baseline ( Table 1 ). The most common endoscopic finding was chronic non-atrophic gastritis (76.7%), followed by hemorrhagic gastritis (12.2.%) and atrophic gastritis (11.1%). Patients were diagnosed with H. pylori infection if they had a positive test result for one of three diagnostic methods, namely, the rapid urease test, H. pylori culture, and histologic examination, as demonstrated in Table 1 . One patient in the probiotic group (lost to follow-up) and one patient in the placebo group (amoxicillin allergy) were excluded from the ITT analysis ( Figure 2 ).

H. pylori eradication is recommended for reducing dyspeptic symptoms and preventing gastric cancer (1, 17). Standard triple therapy has been used for H. pylori eradication since the 1990s (18). However, over the last decade, its efficacy has dropped to 80% or less, and it is no longer recommended as a first-line treatment in regions with high clarithromycin resistance (1, 19). This randomized, double-blind, placebo-controlled study demonstrated that triple therapy with a probiotic as an adjuvant could yield an excellent eradication rate. Furthermore, reduced therapy side effects, such as gastrointestinal symptoms (i.e., bloating, diarrhea, bitter taste, and nausea) and improved quality-of-life scores were also reported in the probiotic group.

Adding probiotics to standard triple therapy significantly improved the eradication rate in the probiotic group (shown by per-protocol analysis) compared with the placebo group (90.9% vs. 75.0%, p = 0.047). The results of this study agree with those of previous trials in which triple therapy was used as a regimen for H. pylori eradication (20, 21); other studies, using different or non-viable strains of probiotics, demonstrated conflicting results (22, 23). We reviewed nine previous studies that demonstrated better eradication rates of triple therapy with probiotics than with placebo, as shown in Supplementary Table 1 (15, 21, 24–30). Most studies used a 7-day triple therapy regimen, except for one in Croatia, which used a 14-day regimen. Each study used a different probiotic protocol (i.e., before, during, or after triple therapy). Only three studies reported high clarithromycin resistance, which was not different between the probiotic and placebo groups (21, 29, 30). The subgroup analysis of clarithromycin-resistant strains in our study revealed that there was no difference in the eradication rates between the probiotic and placebo groups, which was similar to the findings of a study conducted in Japan (eradication rates: 38.5% vs. 28.0%, respectively, p=0.428) (21). This emphasizes that the primary cause of treatment failure of triple therapy is clarithromycin resistance.

Antibiotic resistance is a key factor associated with H. pylori treatment failure (31). The high clarithromycin resistance rate (24%) in this study could have contributed to eradication failure after triple therapy. However, the eradication rate of triple therapy with probiotics in our study was still as high as 90.9% in the PP analysis. The combined effects of lowered amounts of H. pylori and decreased side effects because of probiotics might improve the eradication rate even for antibiotic-resistant strains. For clarithromycin-sensitive strains, added benefits of reducing adverse events were reported in the probiotic group, while excellent eradication rates (96%–100%) were already demonstrated in both probiotic and placebo groups (32). Since there was only a small number of clarithromycin-resistant strain in the probiotic arm in this study, whether or not the addition of probiotics could yield a better eradication rate for antibiotic-resistant strains than the addition of a placebo is still to be determined in future research.

Our study used probiotics during and after H. pylori treatment, as we presumed that probiotics could relieve adverse events while patients were undergoing antibiotic therapy and improve gut dysbiosis after H. pylori eradication. The two prior randomized trials from our center using single-strain probiotics reported significantly decreased adverse events in the probiotic arm, but no statistical difference in eradication rates between the probiotic and the placebo group (33, 34). However, this study showed a significantly higher eradication rate in the probiotic arm, which is in agreement with the generally superior H. pylori eradication effects reported for Lactobacillus strains or multi-strain probiotics (9, 35). A recent study reported that L. acidophilus and L. rhamnosus could directly decrease the H. pylori bacterial load without observed alterations in gut microbiota diversity and composition (36). In addition to conferring direct protective effects by maintaining gut barrier function, L. rhamnosus and L. helveticus can also reduce the incidence of antibiotic-associated diarrhea, which might explain the substantial reduction in antibiotic-related side effects, such as bloating and diarrhea, observed in the probiotic group in our study (10). After successful eradication, there will be an improvement of H. pylori-induced gastric microbial dysbiosis and restoration of normal microbiota (37). A previous study revealed that 14-day triple therapy could induce minimal perturbation of gut microbiota until the recovery of dysbiosis 8 weeks after eradication therapy (38). One study demonstrated that long-term dietary supplementation of L. rhamnosus (30 weeks) could reduce the levels of serum cytokines (tumor necrosis factor α and interleukin-10), modulate the immune response, and alter the gut microbiome. The abundance of Helicobacteraceae also decreased in the group treated with L. rhamnosus. Microbial dysbiosis might be alleviated by probiotic supplementation (39). Therefore, the probiotic treatment was extended for another 4 weeks after the completion of triple therapy as we thought that it might help to accelerate the restoration of gut microbiota and consequently relieve gastrointestinal symptoms such as bloating, nausea, and diarrhea.

The significant improvement of gastrointestinal symptoms and general health scores were also reported in the probiotic group after treatment. The improvement in the GSRS score was comparable to that reported in a previous study using triple therapy with Lactobacillus reuteri (40), but another trial reported no difference in the GSRS score after treatment (41). The difference among studies was that in ours, treatment with probiotics continued for a longer period (4 weeks) after the completion of H. pylori treatment than in other studies (2 weeks). Moreover, the trial reporting no difference in the GSRS score was a single-blind study, and no antibiotic susceptibility testing was conducted in either study. Better general health scores as one indicator of quality of life were also demonstrated in this study. Quality of life is uncommonly evaluated in the study of H. pylori treatment with probiotics. There was only one study reporting improved quality of life by SF-36 after a 2-week H. pylori eradication regimen (42). Our study exhibited better improvement of general health in the probiotic group after completion of H. pylori treatment and probiotics (week 6).

In conclusion, 14-day standard triple therapy with probiotic supplement yielded an excellent H. pylori eradication rate compared with that observed in the placebo group, which was suboptimal. Adding probiotics as an adjuvant to standard triple therapy also reduced antibiotic-associated adverse events, and improved patients’ gastrointestinal symptom scores and their general health-related quality of life after treatment.

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

The studies involving humans were approved by the Human Research Ethics Committee of Thammasat University, Thailand. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

Conceptualization: AK and RV. Data curation: AK, NA, and RV. Formal analysis: AK. Funding acquisition: RV. Investigation: AK and NA. Methodology: AK, NA, and RV. Project administration: RV. Resources: NA and RV. Software: AK. Supervision: VM and RV. Validation: AK, NA, and RV. Visualization: AK and NA. Writing—original draft: AK and NA. Writing—review and editing: BP, SC, SS, PB, PN, NI, VM, and RV. All authors contributed to the article and approved the submitted version.