Impact of the Gastro-Intestinal Bacterial Microbiome on Helicobacter-Associated Diseases

Comparison of three different molecular biology assays (AllPlexTMH. pylori & ClariR assay, Amplidiag® H. pylori + ClariR and RIDA®GENE Helicobacter pylori) to detect Helicobacter pylori and clarithromycin resistance in stool samples

Helicobacter pylori detection and susceptibility profile using feces could optimize guided therapy, when endoscopy is not necessary. This study evaluated the performances of three tests: AllPlexH.pylori&ClariR, RIDAGENEHelicobacterpylori and AmplidiagH.pylori+ClariR assays on stool samples. Stool samples from a documented cohort (50 positive and 25 negative) were analyzed. The gold standard was a composite based on PCR targeting H. pylori and 23S rDNA mutations (A2142C, A2142G, A2143G) on gastric biopsies; and biopsy culture for H.pylori and susceptibility testing. For AllPlex, RidaGene and Amplidiag assays respectively: 55 (73.3%), 75 (100%), 54 (72%) samples could be analyzed; (for detection of H. pylori), sensitivity was 36% (95%CI]28;52%[); 32% (95%CI]21;46%[) and 93% (95%CI]87;100%[); specificity was 100% (95%CI]81;100%[), 83% (95%CI]68;91%[) and 57% (95%CI]33;79%[). (for the Clarithromycin resistance), sensitivity was 18% (95%CI]5;48%[), 25% (95%CI]9;53%[) and 67% (95%CI]39;86%[); specificity was 100% (95%CI]92;100%[). 92% (95%CI]83;97%[) and 97% (95%CI]89;99%[). Innovative technologies could become invaluable tools for mass testing after improvement.

Gut bacterial and fungal dysbiosis in tuberculosis patients

BACKGROUND

Recent studies have more focused on gut microbial alteration in tuberculosis (TB) patients. However, no detailed study on gut fungi modification has been reported till now. So, current research explores the characteristics of gut microbiota (bacteria)- and mycobiota (fungi)-dysbiosis in TB patients and also assesses the correlation between the gut microbiome and serum cytokines. It may help to screen the potential diagnostic biomarker for TB.

RESULTS

The results show that the alpha diversity of the gut microbiome (including bacteria and fungi) decreased and altered the gut microbiome composition of TB patients. The bacterial genera Bacteroides and Prevotella were significantly increased, and Blautia and Bifidobacterium decreased in the TB patients group. The fungi genus Saccharomyces was increased while decreased levels of Aspergillus in TB patients. It indicates that gut microbial equilibrium between bacteria and fungi has been altered in TB patients. The fungal-to-bacterial species ratio was significantly decreased, and the bacterial-fungal trans-kingdom interactions have been reduced in TB patients. A set model including Bacteroides, Blautia, Eubacterium_hallii_group, Apiotrichum, Penicillium, and Saccharomyces may provide a better TB diagnostics option than using single bacterial or fungi sets. Also, gut microbial dysbiosis has a strong correlation with the alteration of IL-17 and IFN-γ.

CONCLUSIONS

Our results demonstrate that TB patients exhibit the gut bacterial and fungal dysbiosis. In the clinics, some gut microbes may be considered as potential biomarkers for auxiliary TB diagnosis.

Bacterial synergies and antagonisms affecting Pseudomonas aeruginosa virulence in the human lung, skin and intestine

Pseudomonas aeruginosa requires a significant breach in the host defense to cause an infection. While its virulence factors are well studied, its tropism cannot be explained only by studying its interaction with the host. Why are P. aeruginosa infections so rare in the intestine compared with the lung and skin? There is not enough evidence to claim specificity in virulence factors deployed by P. aeruginosa in each anatomical site, and host physiology differences between the lung and the intestine cannot easily explain the observed differences in virulence. This perspective highlights a relatively overlooked parameter in P. aeruginosa virulence, namely, potential synergies with bacteria found in the human skin and lung, as well as antagonisms with bacteria of the human intestine.

Comparison of genomic and transcriptional microbiome analysis in gastric cancer patients and healthy individuals

BACKGROUND

Helicobacter pylori and the stomach microbiome play a crucial role in gastric carcinogenesis, and detailed characterization of the microbiome is necessary for a better understanding of the pathophysiology of the disease. There are two common modalities for microbiome analysis: DNA (16S rRNA gene) and RNA (16S rRNA transcript) sequencing. The implications from the use of one or another sequencing approach on the characterization and comparability of the mucosal microbiome in gastric cancer (GC) are poorly studied.

AIM

To characterize the microbiota of GC using 16S rRNA gene and its transcript and determine difference in the bacterial composition.

METHODS

In this study, 316 DNA and RNA samples extracted from 105 individual stomach biopsies were included. The study cohort consisted of 29 healthy control individuals and 76 patients with GC. Gastric tissue biopsy samples were collected from damaged mucosa and healthy mucosa at least 5 cm from the tumor tissue. From the controls, healthy stomach mucosa biopsies were collected. From all biopsies RNA and DNA were extracted. RNA was reverse transcribed into cDNA. V1-V2 region of bacterial 16S rRNA gene from all samples were amplified and sequenced on an Illumina MiSeq platform. Bray-Curtis algorithm was used to construct sample-similarity matrices abundances of taxonomic ranks in each sample type. For significant differences between groups permutational multivariate analysis of variance and Mann-Whitney test followed by false-discovery rate test were used.

RESULTS

Microbial analysis revealed that only a portion of phylotypes (18%-30%) overlapped between microbial profiles obtained from DNA and RNA samples. Detailed analysis revealed differences between GC and controls depending on the chosen modality, identifying 17 genera at the DNA level and 27 genera at the RNA level. Ten of those bacteria were found to be different from the control group at both levels. The key taxa showed congruent results in various tests used; however, differences in 7 bacteria taxa were found uniquely only at the DNA level, and 17 uniquely only at the RNA level. Furthermore, RNA sequencing was more sensitive for detecting differences in bacterial richness, as well as differences in the relative abundance of Reyranella and Sediminibacterium according to the type of GC. In each study group (control, tumor, and tumor adjacent) were found differences between DNA and RNA bacterial profiles.

CONCLUSION

Comprehensive microbial study provides evidence for the effect of choice of sequencing modality on the microbiota profile, as well as on the identified differences between case and control.

New Strategy for the Detection and Treatment of Helicobacter pylori Infections in Primary Care Guided by a Non-Invasive PCR in Stool: Protocol of the French HepyPrim Study

Helicobacter pylori (Hp) infects half of the world population and is responsible for gastric, duodenal ulcers and gastric cancer. The eradication of Hp cures ulcers and prevents ulcer recurrences and gastric cancer. Antibiotic resistance of Hp, and particularly clarithromycin resistance, is the primary cause of treatment failure and is a major concern identified by the WHO as a high priority requiring research into new strategies. Treatments guided by the detection of antibiotic resistance have proven their medical and economical superiority. However, this strategy is severely hampered by the invasive nature of the fibroscopy, since antibiotic resistance detection requires gastric biopsies. The eradication of Hp involves primary care physicians. The objective of this study will be to evaluate the feasibility of a strategy for the management of Hp infection in primary care by a recently developed non-invasive procedure and its non-inferiority in eradication rates compared with the strategy recommended by the French National Authority of Health. The non-invasive procedure is a PCR on stool to detect Hp infection and mutations conferring resistance to clarithromycin allowing a treatment guided by the results of the PCR. We present the protocol of a prospective, multicenter, randomized, controlled interventional study in two arms.

Helicobacter pylori increases the risk of carotid plaque formation: a clinical evidence

Background and aim: Since the relation between Helicobacter pylori (H. pylori) and atherosclerosis has been evidenced, we aimed to analyze whether there is a relationship between the patient's H. pylori infection and age, gender, BMI, blood lipids, and carotid plaque formation.Methods: 810 patients from January 2016 to December 2019 were enrolled in this study, and divided the subjects into H. pylori (+) group and H. pylori (-) group based on the results of UBT. To analyze whether H. pylori infection is related to gender, age, BMI, blood lipids, and neck vascular plaque formation.Results: The single-factor analysis showed that the BMI ≥ 25kg/m2, triglycerides >1.7 mmol/l, the formation of cervical plaques were significantly higher in patients infected with H. pylori in compared to normal cases. Also, multi-variant logistic regression analysis showed that H. pylori infection affects the BMI ≥ 25kg/m2 and triglycerides >1.7 mmol/l to induce vascular plaque. Also, we showed that patients with H. pylori infection are 1.424 times higher than the non-infected group to have triglycerides more elevated than 1.7mmol/l.Conclusion: In this study, we conclude that H. pylori infection is an independent risk factor for higher BMI (>25), triglyceride (>1.7 mmol/l), and neck vascular plaque formation. The multi-variant analysis showed that patients with H. pylori infection are prone to have higher BMI, triglycerides, and neck vascular plaque formation over 1.4-times higher in non-infected individuals.KEY MESSAGESH. pylori infection is an independent risk factor for higher BMI, triglyceride, and neck vascular plaque formation.H. pylori can accelerate vascular plaque formation through increasing BMI and triglyceride.

Helicobacter pylori infection and peptic ulcer disease in cirrhotic patients: An updated meta-analysis

BACKGROUND

Peptic ulcer (PU) is more prevalent in patients with liver cirrhosis. The role of Helicobacter pylori (H. pylori) infection in the pathogenesis of PU in patients with cirrhosis is still not elucidated.

AIM

To perform a meta-analysis on the prevalence of H. pylori infection and PU and their association in liver cirrhosis patients.

METHODS

We searched PubMed, EMBASE, Web of Science, Cochrane, CNKI, Wangfang, and CQVIP databases from inception to July 10, 2020. Odds ratio (OR) and 95% confidence interval (CI) were pooled using a random-effects model. The statistical heterogeneity among studies (I 2-index), subgroup analyses, regression analysis, sensitivity analysis, and the possibility of publication bias were assessed.

RESULTS

A total of 14 studies (13 cross-sectional studies; 1 cohort study) involving 2775 individuals (611 cases with PU and 2164 controls) were included in our meta-analysis. The prevalence of PU in patients with cirrhosis was 22%. The prevalence of H. pylori infection was 65.6% in cirrhotic patients with PU, and 52.5% in those without. The pooled overall OR was 1.73 (95%CI: 1.16-2.56, I 2 = 66.2%, P < 0.001, Z = 2.7, P z < 0.05). We did not find the cause of heterogeneity in the subgroup analyses and meta-regression analysis except for one study. Funnel plot did not show significant publication bias. The results of Begg's test and Egger's test indicated no evidence of substantial publication bias (P Begg = 0.732, P Egger = 0.557).

CONCLUSION

There is a weakly positive association between H. pylori infection and PU in patients with liver cirrhosis. It is suggested that H. pylori infection may play a role in the pathogenesis of PU in liver cirrhotic patients.

Ginger Extract Modulates the Production of Chemokines CCL17, CCL20, CCL22, and CXCL10 and the Gene Expression of Their Receptors in Peripheral Blood Mononuclear Cells from Peptic Ulcer Patients Infected with Helicobacter pylori

Background: The imbalanced expression of chemokines plays critical role in the development of Helicobacter pylori-mediated complications. Objectives: Our aim was to determine ginger extract (GE) effects on the expression of chemokines CCL17, CCL20, CCL22, and CXCL10, as well as CCR4, CCR6, and CXCR3 receptors by peripheral blood mononuclear cells (PBMCs) from H. pylori -infected patients with peptic ulcer (PU). Methods: Peripheral blood mononuclear cells were obtained from 20 patients with H. pylori-associated PU, 20 H. pylori-infected asymptomatic subjects (HAS), and 20 non-infected healthy subjects (NHS). The PBMCs were stimulated by 10 µg/mL of H. pylori-derived crude extract (HPCE) in the presence of 0, 10, 20, and 30 µg/mL of GE. After 36 hours, the supernatant and the RNA extracted from the cells were tested for chemokine concentration and chemokine receptor expression using ELISA and real-time PCR techniques, respectively. Results: In PU patients, treating HPCE-stimulated PBMCs with 10, 20, or 30 µg/mL GE reduced the production of CXCL10 (1.47, 1.5, and 1.53 folds, respectively, P < 0.001 for all), CCL20 (1.44, 1.62, and 1.65 folds, respectively, P < 0.003), and treatment with 30 µg/mL GE increased CCL17 (1.28-fold, P < 0.001) and CCL22 (1.59-fold, P < 0.001) production compared with untreated HPCE-stimulated PBMCs. In PU patients, the HPCE-stimulated PBMCs treated with 10, 20, or 30 µg/mL GE expressed lower levels of CXCR3 (1.9, 3, and 3.5 folds, respectively, P < 0.001) and CCR6 (2.3, 2.7, and 2.8 folds, respectively, P < 0.002) while treating with 10 µg/mL GE upregulated CCR4 (1.7 fold, P = 0.003) compared with untreated HPCE-stimulated PBMCs. Conclusions: Ginger extract modulated the expression of chemokines and their receptors in the PBMCs derived from H. pylori-infected PU patients. The therapeutic potentials of ginger for treating HP-related complications need to be further explored.

Prognostic Role of Intragastric Cytopathology and Microbiota in Surgical Patients with Stomach Cancer

Background:

In the last decade, analysis of malignant cells and flora in gastric lavage (GL) has provided interesting data on pathogenesis of gastric cancer (GC). For this study, combining such two aspects into one cyto-microbiologic category, we tested the prognostic role of the presence/absence of cancer cells (GL1/GL0) and bacterial microbiota (MB1/MB0) in our GC population.

Material and Methods:

Between April 2012 and August 2019, 79 surgical patients with GC were prospectively investigated with the determination of GL MB.

Results:

Compared with GL1 MB0, GL1 MB1 strongly correlated with advanced GC, portended poorer overall survival (OS) (45.8 months vs 20.5 months, P = 0.049), and resulted a significant (P = 0.008) and an independent (P = 0.013) prognostic factor unfavorable for OS.

Conclusion:

In the light of our results, the cyto-microbiologic parameter of GL MB should be used to gain a better prognosis of GC patients. Administration of antimicrobial treatment for MB1 subjects should be entertained because it could reduce the risk of oncogenesis.

Gut-Skin Axis: Current Knowledge of the Interrelationship between Microbial Dysbiosis and Skin Conditions

The microbiome plays an important role in a wide variety of skin disorders. Not only is the skin microbiome altered, but also surprisingly many skin diseases are accompanied by an altered gut microbiome. The microbiome is a key regulator for the immune system, as it aims to maintain homeostasis by communicating with tissues and organs in a bidirectional manner. Hence, dysbiosis in the skin and/or gut microbiome is associated with an altered immune response, promoting the development of skin diseases, such as atopic dermatitis, psoriasis, acne vulgaris, dandruff, and even skin cancer. Here, we focus on the associations between the microbiome, diet, metabolites, and immune responses in skin pathologies. This review describes an exhaustive list of common skin conditions with associated dysbiosis in the skin microbiome as well as the current body of evidence on gut microbiome dysbiosis, dietary links, and their interplay with skin conditions. An enhanced understanding of the local skin and gut microbiome including the underlying mechanisms is necessary to shed light on the microbial involvement in human skin diseases and to develop new therapeutic approaches.

Helicobacter pylori Related Diseases and Osteoporotic Fractures (Narrative Review)

Osteoporosis (OP) and osteoporotic fractures (OFs) are common multifactorial and heterogenic disorders of increasing incidence. Helicobacter pylori (H.p.) colonizes the stomach approximately in half of the world's population, causes gastroduodenal diseases and is prevalent in numerous extra-digestive diseases known to be associated with OP/OF. The studies regarding relationship between H.p. infection (HPI) and OP/OFs are inconsistent. The current review summarizes the relevant literature on the potential role of HPI in OP, falls and OFs and highlights the reasons for controversies in the publications. In the first section, after a brief overview of HPI biological features, we analyze the studies evaluating the association of HPI and bone status. The second part includes data on the prevalence of OP/OFs in HPI-induced gastroduodenal diseases (peptic ulcer, chronic/atrophic gastritis and cancer) and the effects of acid-suppressive drugs. In the next section, we discuss the possible contribution of HPI-associated extra-digestive diseases and medications to OP/OF, focusing on conditions affecting both bone homeostasis and predisposing to falls. In the last section, we describe clinical implications of accumulated data on HPI as a co-factor of OP/OF and present a feasible five-step algorithm for OP/OF risk assessment and management in regard to HPI, emphasizing the importance of an integrative (but differentiated) holistic approach. Increased awareness about the consequences of HPI linked to OP/OF can aid early detection and management. Further research on the HPI-OP/OF relationship is needed to close current knowledge gaps and improve clinical management of both OP/OF and HPI-related disorders.

Gastric cancer - histopathological correlations between tumor and non-tumor gastric mucosa changes

Gastric cancer is a widely geographically distributed malignancy with high prevalence, therefore being a serious health problem that needs standardized methods for early diagnosis and treatment. The aim of the study was to evaluate the correlation of some epidemiological and clinical data with the histological features. The study group was made up of 66 patients that underwent surgical removal of the gastric neoplasm, and the pathological exam showed the morphological features of the tumor, as well as the ones of the unaffected mucosal tissue. Topographically, the highest incidence of the tumor was registered in the gastric antrum, but in recent years, an increased incidence of the superior gastric pole localization was recorded. The macroscopic aspects reveal that the ulcerated type 2 Borrmann is the most frequent, and alongside type 3 Borrmann, the ulcer-infiltrative type represents most of the gastric antrum cancers. The analysis of the tumor invasion showed that most carcinomas underwent surgery when the tumor invaded the serosa (pT3) or even the perigastric tissues (pT4). In our research, we chose Goseki's microscopic classification because of its best coverage of the histological heterogeneity of the gastric carcinomas, providing information about the percentage of the cellular and secretory differentiation with direct impact on the invasion of the tumor. In more than 70% of the cases, the patients showed lesions of severe chronic atrophic gastritis of the non-tumor mucosa. Lately, the incidence of Helicobacter pylori has been 5.5%, lower than indicated by mainstream literature. We observed that the incidence of type 3 incomplete intestinal metaplasia, as the most commonly involved factor in the etiopathogenesis of gastric neoplasms, was encountered in 36.3% of the cases, this percentage rising proportionally with age and being frequently associated with antrum tumors. In conclusion, the permanent analysis of the relation between epidemiological data and some histological features might be relevant for the characterization of the tumoral process or the non-tumor gastric mucosa, leading to an evaluation of the prognosis.

Where to Biopsy to Detect Helicobacter pylori and How Many Biopsies Are Needed to Detect Antibiotic Resistance in a Human Stomach

This study aims to determine the gastric distribution, density, and diversity of Helicobacter pylori infection. Subtotal resection of the stomachs of three H. pylori-infected and asymptomatic obese patients were collected after a sleeve gastrectomy. Distribution and density of H. pylori were determined using culture and RT-PCR on multiple gastric sites (88, 176, and 101 biopsies per patient). Diversity of H. pylori strains was studied using antibiotic susceptibility testing, random amplified polymorphism DNA (RAPD) typing and cagA gene detection on single-colony isolates (44, 96, and 49 isolates per patient). H. pylori was detected in nearly all analyzed sites (354/365 biopsies, 97%). Antral density was higher in one patient only. The three stomachs were almost exclusively infected by an antibiotic-susceptible strain. One clarithromycin-resistant isolate in one biopsy was detected in two stomachs (1/44 and 1/49 isolates), while in the third one, eight (8/96 isolates) metronidazole-resistant isolates were detected. DNA typing showed infection with cagA-negative strains for one patient, cagA-positive strains for a second patient and the third patient was infected with two different strains of distinct cagA genotypes. Infection with H. pylori is shown to spread to the whole surface of the stomach, but a possibility of minor sub-population of antibiotic-resistant clones, undetectable in routine practice.

Patients infected with Mycobacterium africanum versus Mycobacterium tuberculosis possess distinct intestinal microbiota

Background

Mycobacterium tuberculosis complex (MTBC), the causative agent of tuberculosis (TB), is composed of eight subspecies. TB in West Africa, in contrast to other geographical regions, is caused by Mycobacterium africanum (MAF) in addition to M. tuberculosis (MTB), with both infections presenting similar symptoms. Nevertheless, MAF is considered to be hypovirulent in comparison with MTB and less likely to progress to active disease. In this study, we asked whether MAF and MTB infected patients possess distinct intestinal microbiomes and characterized how these microbiota communities are affected by anti-tuberculosis therapy (ATT). Additionally, we assessed if the changes in microbiota composition following infection correlate with pathogen induced alterations in host blood-gene expression.

Methods

A longitudinal, clinical study of MAF infected, MTB infected patients assessed at diagnosis and two months after start of ATT, and healthy, endemic controls was conducted to compare compositions of the fecal microbiome as determined by 16S rRNA sequencing. A blood transcriptome analysis was also performed on a subset of subjects in each group by microarray and the results cross-compared with the same individual’s microbiota composition.

Findings

MAF participants have distinct microbiomes compared with MTB patients, displaying decreased diversity and increases in Enterobacteriaceae with respect to healthy participants not observed in the latter patient group. Interestingly, this observed elevation in Enterobacteriaceae positively correlated with enhanced inflammatory gene expression in peripheral blood and was reversed after initiation of ATT.

Interpretation

Our findings indicate that MAF and MTB have distinct associations with the gut microbiome that may be reflective of the differential susceptibility of West Africans to these two co-endemic infections either as biomarkers or as a contributing determinant.

Mycobacterium africanum (MAF) is a hypovirulent mycobacterium species that is co-endemic with Mycobacterium tuberculosis (MTB) in West Africa and is selectively responsible for up to half the tuberculosis cases in this region. Why some individuals become infected with MAF versus MTB is unclear but has been suggested to be determined by differential host immune competency. Since the microbiome has now been implicated in numerous studies to generally influence host resistance to disease, we investigated whether differences in the intestinal microbiota might associate with MAF as compared with MTB infection. This report presents the first analysis of the intestinal microbiome of MAF-infected subjects as well as a comparison with the microbiota of co-endemic MTB patients and reveals that the microbiota of individuals with MAF infection display both decreased diversity and distinct differences in microbial taxa when compared to both MTB-infected and healthy controls. Furthermore, our data reveal for the first time in TB patients a correlation between the abundance of certain taxa and host blood transcriptional changes related to immune function. Our study also establishes that antibiotic treatment induces parallel changes in the gut microbiota of MAF- and MTB-infected patients. Although not directly addressed in the present study, the findings presented here raise the possibility that the microbiota or other host physiologic or immune factors closely associated with it may be a factor underlying the differential susceptibility of West Africans to MAF infection. In addition, the data identify certain commensal taxa that could be tested in future studies as specific determinants of this association.

Are Helicobacter pylori Infection and Fucoidan Consumption Associated with Fucoidan Absorption?

We examined the associations of Helicobacter pylori and mozuku consumption with fucoidan absorption. Overall, 259 Japanese volunteers consumed 3 g fucoidan, and their urine samples were collected to measure fucoidan values and H. pylori titers before and 3, 6, and 9 h after fucoidan ingestion. Compared to the basal levels (3.7 ± 3.4 ng/mL), the urinary fucoidan values significantly increased 3, 6, and 9 h (15.3 ± 18.8, 24.4 ± 35.1, and 24.2 ± 35.2 ng/mL, respectively) after fucoidan ingestion. The basal fucoidan levels were significantly lower in H. pylori-negative subjects who rarely ate mozuku than in those who regularly consumed it. Regarding the ΔMax fucoidan value (highest value − basal value) in H. pylori-positive subjects who ate mozuku at least once a month, those aged ≥40 years exhibited significantly lower values than <40 years old. Among subjects ≥40 years old who regularly consumed mozuku, the ΔMax fucoidan value was significantly lower in H. pylori-positive subjects than in H. pylori-negative ones. In H. pylori-positive subjects who ate mozuku at least once monthly, basal fucoidan values displayed positive correlations with H. pylori titers and ΔMax fucoidan values in subjects <40 years old. No correlations were found in H. pylori-positive subjects who ate mozuku once every 2–3 months or less. Thus, fucoidan absorption is associated with H. pylori infection and frequency of mozuku consumption.

Diagnostic Accuracy of a Noninvasive Test for Detection of Helicobacter pylori and Resistance to Clarithromycin in Stool by the Amplidiag H. pylori+ClariR Real-Time PCR Assay

The noninvasive detection of Helicobacter pylori and its resistance to clarithromycin could revolutionize the management of H. pylori-infected patients by tailoring eradication treatment without any need for endoscopy when histology is not necessary. Several real-time PCR tests performed on stools have been proposed, but their performances were either poor or they were tested on too few patients to be properly evaluated. We conducted a prospective, multicenter study including 1,200 adult patients who were addressed for gastroduodenal endoscopy with gastric biopsies and who were naive for eradication treatment in order to evaluate the performance of the Amplidiag H. pylori+ClariR assay recently developed by Mobidiag (Espoo, Finland). The results of the Amplidiag H. pylori+ClariR assay performed on DNA from stools (automatic extraction with the EasyMag system [bioMérieux]) were compared with those of culture/Etest and quadruplex real-time PCRs performed on two gastric biopsy samples (from the antrum and corpus) to detect the H. pylori glmM gene and mutations in the 23S rRNA genes conferring clarithromycin resistance. The sensitivity and specificity of the detection of H. pylori were 96.3% (95% confidence interval [CI], 92 to 98%) and 98.7% (95% CI, 97 to 99%), respectively. The positive and negative predictive values were evaluated to be 92.2% (95% CI, 92 to 98%) and 99.3% (95% CI, 98 to 99%), respectively. In this cohort, 160 patients (14.7%) were found to be infected (positive by culture and/or PCR). The sensitivity and specificity for detecting resistance to clarithromycin were 100% (95% CI, 88 to 100%) and 98.4% (95% CI, 94 to 99%), respectively.

The role of the gastric bacterial microbiome in gastric cancer: Helicobacter pylori and beyond

A link between chronic inflammation and carcinogenesis has been depicted in many organ systems. Helicobacter pylori is the most prevalent bacterial pathogen, induces chronic gastritis and is associated with more than 90% of cases of gastric cancer (GC). However, the introduction of nucleotide sequencing techniques and the development of biocomputional tools have surpassed traditional culturing techniques and opened a wide field for studying the mucosal and luminal composition of the bacterial gastric microbiota beyond H. pylori. In studies applying animal models, a potential role in gastric carcinogenesis for additional bacteria besides H. pylori has been demonstrated. At different steps of gastric carcinogenesis, changes in bacterial communities occur. Whether these microbial changes are a driver of malignant disease or a consequence of the histologic progression along the precancerous cascade, is not clear at present. It is hypothesized that atrophy, as a consequence of chronic gastric inflammation, alters the gastric niche for commensals that might further urge the development of H. pylori-induced GC. Here, we review the current state of knowledge on gastric bacteria other than H. pylori and on their synergism with H. pylori in gastric carcinogenesis.