Distribution of Helicobacter pylori and Periodontopathic Bacterial Species in the Oral Cavity

Viable but non-cultivable state in oral microbiota: a critical review of an underexplored microbial survival strategy

The viable but non-cultivable (VBNC) state and persister cells, two dormancy phenomena in bacteria, differ in various aspects. The entry of bacteria into the VBNC state as a survival strategy under stressful conditions has gained increasing attention in recent years, largely due to the higher tolerance of VBNC cells to antibiotics and antimicrobials resulting from their low metabolic activity. The oral cavity favors biofilm growth in dental hard tissues, resulting in tooth decay and periodontitis. Despite advances in VBNC state detection in the food industry and environment, the entry capability of oral bacteria into the VBNC state remains poorly documented. Furthermore, the VBNC state has recently been observed in oral pathogens, including Porphyromonas gingivalis, which shows potential relevance in chronic systemic infections, Enterococcus faecalis, an important taxon in endodontic infections, and Helicobacter pylori, which exhibits transient presence in the oral cavity. Further research could create opportunities to develop novel therapeutic strategies to control oral pathogens. The inability of conventional culture-based methods to identify VBNC bacteria and the metabolic reactivation of dormant cells to restore susceptibility to therapies highlights a notable gap in anti-VBNC state strategies. The lack of targeted approaches tested for efficacy against VBNC bacteria underscores the need to develop novel detection methods. This review discusses the VBNC state, its importance in public health, and diagnostic techniques, with a special focus on the VBNC state in oral bacteria.

Polymicrobial interactions of Helicobacter pylori and its role in the process of oral diseases

Objective

Helicobacter pylori (H. pylori) infection affects approximately 50% of the global population. The predominant route of H. pylori transmission is through the oral pathway, making the oral cavity highly significant in its infection. This review focuses on the relationship between H. pylori and oral diseases, the influence of H. pylori infection on the oral microbiota, and the potential mechanisms involving certain oral pathogens.

Method

To identify relevant studies, we conducted searches in PubMed, Google Scholar using keywords such as "Helicobacter pylori," "oral diseases, " "oral microorganisms, " without any date restrictions. The retrieved publications were subject to a review.

Results

H. pylori infection is positively correlated with the occurrence of various oral diseases, such as dental caries, periodontitis, and oral lichen planus. H. pylori may affect the oral microbiota through various mechanisms, and there exists an interactive relationship between H. pylori and oral bacteria, including Streptococcus, Porphyromonas gingivalis (P. gingivalis), and Candida albicans (C. albicans).

Conclusions

H. pylori infection has a close relationship with certain oral diseases. H. pylori modulates oral microflora diversity and structure, while eradication therapy and medications have varying impacts on oral microbiota.

Helicobacter pylori in oral cavity: current knowledge

The oral cavity may play a role as a reservoir and in the transmission and colonization of Helicobacter pylori. The route of transmission for H. pylori is not fully understood. The prevalence of this pathogen varies globally, affecting half of the world's population, predominantly in developing countries. Here, we review the prevalence of H. pylori in the oral cavity, the characteristics that facilitate its colonization and dynamics in the oral microbiome, the heterogeneity and diversity of virulence of among strains, and noninvasive techniques for H. pylori detection in oral samples. The prevalence of H. pylori in the oral cavity varies greatly, being influenced by the characteristics of the population, regions where samples are collected in the oral cavity, and variations in detection methods. Although there is no direct association between the presence of H. pylori in oral samples and stomach infection, positive cases for gastric H. pylori frequently exhibit a higher prevalence of the bacterium in the oral cavity, suggesting that the stomach may not be the sole reservoir of H. pylori. In the oral cavity, H. pylori can cause microbiome imbalance and remodeling of the oral ecosystem. Detection of H. pylori in the oral cavity by a noninvasive method may provide a more accessible diagnostic tool as well as help prevent transmission and gastric re-colonization. Further research into this bacterium in the oral cavity will offer insights into the treatment of H. pylori infection, potentially developing new clinical approaches.

Novel MAXPOWER biological antibacterial liquid for eradicating oral Helicobacter pylori

BACKGROUND

Eradication of oral Helicobacter pylori (H. pylori) not only reduces the infection rate from the transmission route but also improves the success rate of intragastric eradication. MAXPOWER Biological Bacteriostatic Liquid, developed in our previous work, is a composite biological preparation with strong antibacterial ability and unique antibacterial mechanism. The present study evaluated the efficacy of the MAXPOWER biocontrol solution on H. pylori and its success rate in eradicating oral H. pylori in clinical patients.

METHODS

Live-dead cell staining and hemolysis test were used to evaluate the cellular safety of MAXPOWER biocontrol solution; plate spreading, live-dead bacterial staining, and scanning electron microscopy methods were used to evaluate its antimicrobial effect against H. pylori. Transcriptomics was used to analyze the changes in H. pylori genes before and after treatment. After seven days of gavage treatment, H&E staining and mice feces were collected for 16SrDNA sequencing to evaluate the animals' safety. Oral H. pylori-positive patients were randomized to be given a placebo and MAXPOWER Bio-Bacteriostatic Liquid gargle for seven days to evaluate the effect on oral H. pylori eradication.

RESULTS

In vitro tests demonstrated that this product has excellent biocompatibility and hemocompatibility and can effectively eradicate oral H. pylori. In vivo tests further showed that it has good biosafety and virtually no adverse effect on intestinal microflora. Transcriptomics analysis revealed that it kills H. pylori cells mainly by disrupting their cell membranes and metabolism. Additionally, the results of randomized controlled trials on humans disclosed that the oral H. pylori eradication rates achieved by MAXPOWER Biological Antibacterial Liquid were 71.4% and 78.9% according to the intention-to-treat and the per-protocol analysis, respectively.

CONCLUSION

MAXPOWER Biological Antibacterial Liquid is both safe and efficacious in the eradication of oral H. pylori.

TRIAL REGISTRATION

This study was retrospectively registered in the ClinicalTrials.gov Trial Registry on 21/09/2023 (NCT06045832).

Characterization of the unique oral microbiome of children harboring Helicobacter pylori in the oral cavity

Objective

Helicobacter pylori infection is acquired in childhood via the oral cavity, although its relationship with the characteristics of the oral microbiome has not been elucidated. In this study, we performed comprehensive analysis of the oral microbiome in children and adults with or without H. pylori in the oral cavity.

Methods

Bacterial DNA was extracted from 41 adult and 21 child saliva specimens, and H. pylori was detected using PCR. 16S rRNA gene amplification was performed for next-generation sequencing. Bioinformatic analyses were conducted using Quantitative Insights into Microbial Ecology 2 (QIIME 2).

Results

Faith's phylogenetic diversity analysis showed a significant difference between H. pylori-negative adult and child specimens in terms of α-diversity (p < 0.05), while no significant difference was observed between H. pylori-positive adult and child specimens. There was also a significant difference in β-diversity between H. pylori-positive and negative child specimens (p < 0.05). Taxonomic analysis at the genus level revealed that Porphyromonas was the only bacterium that was significantly more abundant in both H. pylori-positive adults and children than in corresponding negative specimens (p < 0.01 and p < 0.05, respectively).

Conclusion

These results suggest unique oral microbiome characteristics in children with H. pylori infection in the oral cavity.

Porphyromonas gingivalis infection in the oral cavity is associated with elevated galactose-deficient IgA1 and increased nephritis severity in IgA nephropathy

BACKGROUND

The relationship between the major periodontal bacteria, Porphyromonas gingivalis, and the pathogenesis of IgA nephropathy (IgAN)-particularly with respect to galactose-deficient IgA1 (Gd-IgA1)-has not been fully elucidated.

METHODS

Saliva samples from 30 IgAN patients and 44 patients with chronic kidney disease (CKD) were subjected to analysis of P. gingivalis status via polymerase chain reaction using a set of P. gingivalis-specific primers. The associations between P. gingivalis presence and clinical parameters, including plasma Gd-IgA1, were analyzed in each group.

RESULTS

Compared with the CKD group, the IgAN group demonstrated significantly higher plasma Gd-IgA1 levels (p < 0.05). Compared with the P. gingivalis-negative subgroup, the P. gingivalis-positive subgroup exhibited significantly higher plasma Gd-IgA1 levels in both IgAN and CKD patients (p < 0.05). Additionally, among IgAN patients, the P. gingivalis-positive subgroup displayed significantly higher plasma Gd-IgA1 and urine protein levels, compared with the P. gingivalis-negative subgroup (p < 0.05). With respect to renal biopsy findings, the frequencies of segmental glomerulosclerosis and tubular atrophy/interstitial fibrosis were significantly greater in the P. gingivalis-positive subgroup than in the P. gingivalis-negative subgroup, according to the Oxford classification of IgAN (p < 0.05).

CONCLUSION

Our findings suggest an association between the presence of P. gingivalis in the oral cavity and the pathogenesis of IgAN, mediated by increased levels of Gd-IgA1.

Comparative evaluation of propolis mouthwash with 0.2% chlorhexidine mouthwash as an adjunct to mechanical therapy in improving the periodontitis among perimenopausal women: a randomized controlled trial

OBJECTIVE

To evaluate the efficacy of Propolis mouthwash compared to chlorhexidine mouthwash as an adjunct to mechanical therapy in improving clinical parameters in perimenopausal women with chronic periodontitis.

METHODOLOGY

A double-blind, randomized, controlled clinical trial was conducted by recruiting 144 subjects with mild to moderate chronic periodontitis. After scaling and root planning, subjects were allocated to two treatment groups: 0.2% chlorhexidine mouthwash and 20% propolis mouthwash twice daily for six weeks. Clinical parameters such as pocket probing depth (PPD), clinical attachment loss (CAL) and bleeding on probing (BOP) were analysed at baseline, six weeks, and 12 weeks.

RESULT

The mean value of PPD in the propolis group was 4.67 at baseline, reduced to 4.01 at six weeks and 3.59 at 12 weeks. While in the chlorhexidine group, the baseline value of 4.65 reduced to 4.44 and 4.25 at six weeks and 12 weeks, respectively. The baseline value of the mean CAL in the propolis group was 4.45. This value was reduced to 4.15 at six weeks and 3.77 at 12 weeks. For the chlorhexidine group, the baseline value of CAL was 4.80, which was reduced to 4.50 and 4.19 at six weeks and 12 weeks. The mean value of bleeding on probing in the propolis group was 77.20, which decreased to 46.30 at six weeks and 14.60 at the final visit. In the chlorhexidine group, the mean value of 77.30 was reduced to 49.60 and 22.80 at subsequent visits.

CONCLUSION

This study concludes that both propolis and chlorhexidine mouthwash positively improve clinical parameters; however, propolis is significantly more effective in improving BOP.

TRIAL REGISTRATION

ID: NCT05870059, Date of Registration: 02/02/2022. ( https://beta.

CLINICALTRIALS

gov/study/NCT05870059 ).

Dimethylaminododecyl Methacrylate-Incorporated Dental Materials Could Be the First Line of Defense against Helicobacter pylori

Oral cavity is an essential reservoir for H. pylori. We aimed to investigate the antibacterial effects of dimethylaminododecyl methacrylate (DMADDM) against H. pylori. Modified giomers were prepared by introducing 0%, 1.25% and 2.5% DMADDM monomers. Broth microdilution assay, spot assay, Alamer Blue assay, PMA-qPCR, crystal violet staining, scanning electron microscopy observation and live/dead bacterial staining were performed to evaluate the antibacterial and antibiofilm effects of DMADDM and modified giomers in vitro. Urease assay, qPCR, hematoxylin-eosin staining and ELISA were performed to evaluate the inflammation levels and colonization of H. pylori in vivo. In vitro experiments indicated that the minimum inhibitory concentration and minimum bactericidal concentration of DMADDM were 6.25 μg/mL and 25 μg/mL, respectively. It inhibited H. pylori in a dose- and time-dependent manner, and significantly reduced the expression of cagA, vacA, flaA and ureB. DMADDM-modified giomers inhibited the formation of H. pylori biofilm and reduced live cells within it. In vivo experiments confirmed that the pretreatment with DMADDM-modified dental resin effectively reduced the gastric colonization of oral-derived H. pylori, suppressed systemic and local gastric inflammation. DMADDM monomers and DMADDM-modified giomers possessed excellent antibacterial and antibiofilm effects on H. pylori. Pretreatment with DMADDM-modified giomers significantly inhibited the gastric infection by H. pylori.

Low Prevalence of HSV-1 and Helicobacter pylori in HNSCC and Chronic Tonsillitis Patients Compared to Healthy Individuals

Recent studies identified viral and bacterial factors, including HSV-1 and H. pylori, as possible factors associated with diseases such as chronic tonsillitis and cancers, including head and neck squamous cell carcinoma (HNSCC). We assessed the prevalence of HSV-1/2 and H. pylori in patients with HNSCC, chronic tonsillitis, and healthy individuals using PCR after DNA isolation. Associations were sought between the presence of HSV-1, H. pylori, and clinicopathological and demographic characteristics and stimulant use. HSV-1 and H. pylori were most frequently identified in controls (HSV-1: 12.5% and H. pylori: 6.3%). There were 7 (7.8%) and 8 (8.6%) patients with positive HSV-1 in HNSCC and chronic tonsillitis patients, respectively, while the prevalence of H. pylori was 0/90 (0%) and 3/93 (3.2%), respectively. More cases of HSV-1 were observed in older individuals in the control group. All positive HSV-1 cases in the HNSCC group were associated with advanced tumor stage (T3/T4). The prevalence of HSV-1 and H. pylori was highest in the controls compared to HNSCC and chronic tonsillitis patients, which indicates that the pathogens were not risk factors. However, since all positive HSV-1 cases in the HNSCC group were observed only in patients with advanced tumor stage, we suggested a possible link between HSV-1 and tumor progression. Further follow-up of the study groups is planned.

The Role of Adhesion in Helicobacter pylori Persistent Colonization

Helicobacter pylori (H. pylori) has coevolved with its human host for more than 100 000 years. It can safely colonize around the epithelium of gastric glands via their specific microstructures and proteins. Unless patients receive eradication treatment, H. pylori infection is always lifelong. However, few studies have discussed the reasons. This review will focus on the adhesion of H. pylori from the oral cavity to gastric mucosa and summarize the possible binding and translocation characteristics. Adhesion is the first step for persistent colonization after the directional motility, and factors related to adhesion are necessary. Outer membrane proteins, such as the blood group antigen binding adhesin (BabA) and the sialic acid binding adhesin (SabA), play pivotal roles in binding to human mucins and cellular surfaces. And this may offer different perspectives on eradication.

Analysis of Genetic Relatedness between Gastric and Oral Helicobacter pylori in Patients with Early Gastric Cancer Using Multilocus Sequence Typing

The oral cavity is the second most colonized site of Helicobacter pylori after the stomach. This study aimed to compare the genetic relatedness between gastric and oral H. pylori in Japanese patients with early gastric cancer through multilocus sequence typing (MLST) analysis using eight housekeeping genes. Gastric biopsy specimens and oral samples were collected from 21 patients with a fecal antigen test positive for H. pylori. The number of H. pylori allelic profiles ranged from zero to eight since the yield of DNA was small even when the nested PCR was performed. MLST analysis revealed that only one patient had a matching oral and gastric H. pylori genotype, suggesting that different genotypes of H. pylori inhabit the oral cavity and gastric mucosa. The phylogenetic analysis showed that oral H. pylori in six patients was similar to gastric H. pylori, implying that the two strains are related but not of the same origin, and those strains may be infected on separate occasions. It is necessary to establish a culture method for oral H. pylori to elucidate whether the oral cavity acts as the source of gastric infection, as our analysis was based on a limited number of allele sequences.

Detection of Helicobacter pylori from Extracted Teeth of a Patient with Idiopathic Thrombocytopenic Purpura

Immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by isolated cryptogenic thrombocytopenia due to a transient or persistent reduction in platelet count. Many patients with ITP have shown improved platelet count after Helicobacter pylori eradication therapy. However, there have been no studies regarding H. pylori in the oral cavity of patients with ITP. Here, we describe a patient with ITP whose oral samples exhibited H. pylori. A 64-year-old woman with ITP came to our hospital with chief complaints that required oral surgery, including tooth extraction and cystectomy. Bacterial DNA from H. pylori was confirmed on the extracted tooth, but was not detected in the saliva taken at the time. Bacterial DNA from H. pylori was detected on the suture around the extraction socket, which was removed at 10 days post-operation. However, H. pylori DNA was not detected in other oral samples at 10 or 30 days post-operation. A urea breath test was carried out in the gastrointestinal clinic at 60 days post-operation, which revealed no presence of H. pylori in the gastrointestinal tract. These results suggest that teeth with severe bacterial infections may be a potential reservoir of H. pylori for patients with ITP.

Helicobacter pylori in the Oral Cavity: Current Evidence and Potential Survival Strategies

Helicobacter pylori (H. pylori) is transmitted primarily through the oral–oral route and fecal–oral route. The oral cavity had therefore been hypothesized as an extragastric reservoir of H. pylori, owing to the presence of H. pylori DNA and particular antigens in distinct niches of the oral cavity. This bacterium in the oral cavity may contribute to the progression of periodontitis and is associated with a variety of oral diseases, gastric eradication failure, and reinfection. However, the conditions in the oral cavity do not appear to be ideal for H. pylori survival, and little is known about its biological function in the oral cavity. It is critical to clarify the survival strategies of H. pylori to better comprehend the role and function of this bacterium in the oral cavity. In this review, we attempt to analyze the evidence indicating the existence of living oral H. pylori, as well as potential survival strategies, including the formation of a favorable microenvironment, the interaction between H. pylori and oral microorganisms, and the transition to a non-growing state. Further research on oral H. pylori is necessary to develop improved therapies for the prevention and treatment of H. pylori infection.

The interactions between oral-gut axis microbiota and Helicobacter pylori

In the human body, each microbial habitat exhibits a different microbial population pattern, and these distinctive microflorae are highly related to the development of diseases. The microbial interactions from host different niches are becoming crucial regulators to shape the microbiota and their physiological or pathological functions. The oral cavity and gut are the most complex and interdependent microbial habitats. Helicobacter pylori is one of the most important pathogens from digestive tract, especially the stomach, due to its direct relationships with many gastric diseases including gastric cancer. H. pylori infections can destroy the normal gastric environment and make the stomach a livable channel to enhance the microbial interactions between oral cavity and gut, thus reshaping the oral and gut microbiomes. H. pylori can be also detected in the oral and gut, while the interaction between the oral-gut axis microbiota and H. pylori plays a major role in H. pylori’s colonization, infection, and pathogenicity. Both the infection and eradication of H. pylori and its interaction with oral-gut axis microbiota can alter the balance of the microecology of the oral-gut axis, which can affect the occurrence and progress of related diseases. The shift of oral-gut axis microbiota and their interactions with H. pylori maybe potential targets for H. pylori infectious diagnosis and treatment.

Possible Association of Periodontal Diseases With Helicobacter pylori Gastric Infection: A Systematic Review and Meta-Analysis

Some research has suggested that dental plaque and saliva could be reservoirs of Helicobacter pylori (H. pylori) and be capable of infecting or re-infecting the gastric mucosa after eradication, with certain studies showing a significant association between PD and gastric infection by this bacterium. An electronic search was performed in PubMed, EMBASE, and Web of Science databases with the terms “Helicobacter pylori AND periodontal diseases”; “Helicobacter pylori AND gingivitis”; “Helicobacter pylori AND chronic periodontitis”; “Helicobacter pylori AND periodontitis”; “Helicobacter pylori AND dental plaque”, to identify articles up to September 2021. The Newcastle-Ottawa scale was used to assess study quality. A meta-analysis was performed using RevMan 2020 (Cochane Collaboration) software. A total of 1,315 studies were identified and 12 were included, analyzing 226,086 patients with mean age between 10.5 and 63.4 years. The prevalence of H. pylori in the oral cavity ranged from 5.4 to 83.3%. A random-effects model was used to analyze the presence of H. pylori and subgroups were made according to the method of evaluation (PCR or RUT). Statistical significance was found in the overall analysis (p = 0.01). There is no clear evidence that H. pylori present in oral bacterial plaque causes gastric infection and vice versa.

Chinese Consensus Report on Family-Based Helicobacter pylori Infection Control and Management (2021 Edition)

OBJECTIVE

Helicobacter pylori infection is mostly a family-based infectious disease. To facilitate its prevention and management, a national consensus meeting was held to review current evidence and propose strategies for population-wide and family-based H. pylori infection control and management to reduce the related disease burden.

METHODS

Fifty-seven experts from 41 major universities and institutions in 20 provinces/regions of mainland China were invited to review evidence and modify statements using Delphi process and grading of recommendations assessment, development and evaluation system. The consensus level was defined as ≥80% for agreement on the proposed statements.

RESULTS

Experts discussed and modified the original 23 statements on family-based H. pylori infection transmission, control and management, and reached consensus on 16 statements. The final report consists of three parts: (1) H. pylori infection and transmission among family members, (2) prevention and management of H. pylori infection in children and elderly people within households, and (3) strategies for prevention and management of H. pylori infection for family members. In addition to the 'test-and-treat' and 'screen-and-treat' strategies, this consensus also introduced a novel third 'family-based H. pylori infection control and management' strategy to prevent its intrafamilial transmission and development of related diseases.

CONCLUSION

H. pylori is transmissible from person to person, and among family members. A family-based H. pylori prevention and eradication strategy would be a suitable approach to prevent its intra-familial transmission and related diseases. The notion and practice would be beneficial not only for Chinese residents but also valuable as a reference for other highly infected areas.

Colonization by Various Morphological Forms of Helicobacter pylori in the Gingival Sulcus and Antrum of the Stomach

BACKGROUND

Helicobacter pylori eradication therapy can be considered effective if the result of its implementation is removed including all roots and rootlets from which surviving H. pylori can repopulate in the gastric mucosa. One of the reasons for the ineffectiveness of eradication therapy can be the continuous presence of viable coccoid forms of H. pylori in the oral cavity. Therefore, anti-Helicobacter eradication therapy should be supplemented by the sanitation of the oral cavity.

OBJECTIVES

The objective of this study is to determine the frequency of occurrence of H. pylori in the gastric mucosa and in the oral cavity in patients with chronic periodontitis or with chronic gastritis using immunocytochemical method and to evaluate the pathophysiological relationship between periodontitis and HP-associated acid-dependent stomach diseases mediated by H. pylori.

METHODS

A group of patients with chronic gastritis (70 participants, 46 women, 24 men, age: 24 - 55 years) and another group with chronic periodontitis before the start of surgical treatment (61 participants, 30 women, 31 men, age: 20 - 60 years) were examined for НР bacterial cells using immunocytochemical methods of staining gastric biopsy and exfoliate samples from the gingival sulcus surface. The participants did not take any antimicrobial medication before and during the examination. Routine staining was also performed to view microbiota in smears for both groups. The participants signed a voluntary consent agreement to undergo routine medical examinations and join the study at the Nikiforov Russian Centre of Emergency and Radiation Medicine, EMERCOM of Russia, where the ethical committee was made.

RESULTS

Immunocytochemical method could identify all stages of bacillary-coccoid transformation of H. pylori which accounted for 63.4-67.5% of cases. HP-antigenpositive bacteria were found in the oral cavity in both groups of examined patients. It was apparent that spiral forms of H. pylori were dominant over coccoid forms in the gastric mucosa in the antrum of the stomach, whereas coccoid forms of H. pylori were frequently found more in the oral cavity. Helicobacteriosis in the oral cavity was identified in chronic periodontitis.

CONCLUSION

We found certain pathogenetic connections between inflammatory lesions of the oral cavity and diseases of the internal organs of the gastrointestinal tract. Accordingly, we suggest the necessity to use proper medication for oral cavity sanitation along with anti-Helicobacter eradication therapy to influence the HP reservoir in the oral cavity and gingival sulcus. Additionally, bacterial cells of HP reside in the oral cavity in coccoid forms; therefore, the coccoid form of HP should become the second principal target in treating HP.

Nutrient Deficiency Promotes the Entry of Helicobacter pylori Cells into Candida Yeast Cells

Helicobacter pylori, a Gram-negative bacterium, has as a natural niche the human gastric epithelium. This pathogen has been reported to enter into Candida yeast cells; however, factors triggering this endosymbiotic relationship remain unknown. The aim of this work was to evaluate in vitro if variations in nutrient concentration in the cultured medium trigger the internalization of H. pylori within Candida cells. We used H. pylori-Candida co-cultures in Brucella broth supplemented with 1%, 5% or 20% fetal bovine serum or in saline solution. Intra-yeast bacteria-like bodies (BLBs) were observed using optical microscopy, while intra-yeast BLBs were identified as H. pylori using FISH and PCR techniques. Intra-yeast H. pylori (BLBs) viability was confirmed using the LIVE/DEAD BacLight Bacterial Viability kit. Intra-yeast H. pylori was present in all combinations of bacteria-yeast strains co-cultured. However, the percentages of yeast cells harboring bacteria (Y-BLBs) varied according to nutrient concentrations and also were strain-dependent. In conclusion, reduced nutrients stresses H. pylori, promoting its entry into Candida cells. The starvation of both H. pylori and Candida strains reduced the percentages of Y-BLBs, suggesting that starving yeast cells may be less capable of harboring stressed H. pylori cells. Moreover, the endosymbiotic relationship between H. pylori and Candida is dependent on the strains co-cultured.