Epidemiology of Helicobacter pylori infection in six Latin American countries (SWOG Trial S0701)

The All-Age Prevalence of Helicobacter pylori Infection and Potential Transmission Routes. A Population-Based Study

BACKGROUND AND AIMS

Previous research on H. pylori epidemiology has mostly focused on adult populations. We have aimed to study H. pylori prevalence in all age groups including children and adolescents and to identify potential routes of transmission.

METHODS

Subjects from all age groups (children 0-11 years, adolescents 12-17 years and adults ≥18 years of age), recruited from both an urban and a rural community in Northern Norway, were invited to provide stool samples for the diagnosis of H. pylori antigen and to fill in a questionnaire (adult and adolescents only) on gastrointestinal symptoms, lifestyle factors and biometric data.

RESULTS

A total of 1 624 (35.3%) of the invited subjects, including 173 (39.3%) of the children, 46 (19.2%) of the adolescents, and 1 416 (36.1%) of the adults, responded to the invitation. H. pylori infection was nearly undetectable (0.6%) among the children, whereas the prevalence increased from 20% in adolescents toward a peak of 45% in the highest age group. Univariate analyses of possible risk factors of H. pylori infection showed significant associations to private well water, the use of outhouse toilet, and having farm animals in childhood, but the associations waned in multivariate analyses.

CONCLUSIONS

In our populations, with apparent high hygienic standards, the transmission of H. pylori infection may start not only in childhood, but also in adolescence, where potential transmission routes may be outdoor toilet use, private well water, and farm animals.

Mass Eradication of Helicobacter pylorito Prevent Gastric Cancer: Theoretical and Practical Considerations

Although the age-adjusted incidence of gastric cancer is declining, the absolute number of new cases of gastric cancer is increasing due to population growth and aging. An effective strategy is needed to prevent this deadly cancer. Among the available strategies, screen-and-treat for Helicobacter pylori infection appears to be the best approach to decrease cancer risk; however, implementation of this strategy on the population level requires a systematic approach. The program also must be integrated into national healthcare priorities to allow the limited resources to be most effectively allocated. Implementation will require adoption of an appropriate screening strategy, an efficient delivery system with a timely referral for a positive test, and standardized treatment regimens based on clinical efficacy, side effects, simplicity, duration, and cost. Within the population, there are subpopulations that vary in risk such that a "one size fits all" approach is unlikely to be ideal. Sensitivity analyses will be required to identify whether the programs can be utilized by heterogeneous populations and will likely require adjustments to accommodate the needs of subpopulations.

Hydrogen Metabolism in Helicobacter pylori Plays a Role in Gastric Carcinogenesis through Facilitating CagA Translocation

A known virulence factor of Helicobacter pylori that augments gastric cancer risk is the CagA cytotoxin. A carcinogenic derivative strain, 7.13, that has a greater ability to translocate CagA exhibits much higher hydrogenase activity than its parent noncarcinogenic strain, B128. A Δhyd mutant strain with deletion of hydrogenase genes was ineffective in CagA translocation into human gastric epithelial AGS cells, while no significant attenuation of cell adhesion was observed. The quinone reductase inhibitor 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO) was used to specifically inhibit the H2-utilizing respiratory chain of outer membrane-permeabilized bacterial cells; that level of inhibitor also greatly attenuated CagA translocation into AGS cells, indicating the H2-generated transmembrane potential is a contributor to toxin translocation. The Δhyd strain showed a decreased frequency of DNA transformation, suggesting that H. pylori hydrogenase is also involved in energizing the DNA uptake apparatus. In a gerbil model of infection, the ability of the Δhyd strain to induce inflammation was significantly attenuated (at 12 weeks postinoculation), while all of the gerbils infected with the parent strain (7.13) exhibited a high level of inflammation. Gastric cancer developed in 50% of gerbils infected with the wild-type strain 7.13 but in none of the animals infected with the Δhyd strain. By examining the hydrogenase activities from well-defined clinical H. pylori isolates, we observed that strains isolated from cancer patients (n = 6) have a significantly higher hydrogenase (H2/O2) activity than the strains isolated from gastritis patients (n = 6), further supporting an association between H. pylori hydrogenase activity and gastric carcinogenesis in humans.

IMPORTANCE

Hydrogen-utilizing hydrogenases are known to be important for some respiratory pathogens to colonize hosts. Here a gastric cancer connection is made via a pathogen's (H. pylori) use of molecular hydrogen, a host microbiome-produced gas. Delivery of the known carcinogenic factor CagA into host cells is augmented by the H2-utilizing respiratory chain of the bacterium. The role of hydrogenase in carcinogenesis is demonstrated in an animal model, whereby inflammation markers and cancer development were attenuated in the hydrogenase-null strain. Hydrogenase activity comparisons of clinical strains of the pathogen also support a connection between hydrogen metabolism and gastric cancer risk. While molecular hydrogen use is acknowledged to be an alternative high-energy substrate for some pathogens, this work extends the roles of H2 oxidation to include transport of a carcinogenic toxin. The work provides a new avenue for exploratory treatment of some cancers via microflora alterations.

Quantitative Detection and Genotyping of Helicobacter pylori from Stool using Droplet Digital PCR Reveals Variation in Bacterial Loads that Correlates with cagA Virulence Gene Carriage

BACKGROUND

Epidemiologic studies of the carcinogenic stomach bacterium Helicobacter pylori have been limited by the lack of noninvasive detection and genotyping methods. We developed a new stool-based method for detection, quantification, and partial genotyping of H. pylori using droplet digital PCR (ddPCR), which allows for increased sensitivity and absolute quantification by PCR partitioning.

MATERIALS AND METHODS

Stool-based ddPCR assays for H. pylori 16S gene detection and cagA virulence gene typing were tested using a collection of 50 matched stool and serum samples from Costa Rican volunteers and 29 H. pylori stool antigen-tested stool samples collected at a US hospital.

RESULTS

The stool-based H. pylori 16S ddPCR assay had a sensitivity of 84% and 100% and a specificity of 100% and 71% compared to serology and stool antigen tests, respectively. The stool-based cagA genotyping assay detected cagA in 22 (88%) of 25 stools from CagA antibody-positive individuals and four (16%) of 25 stools from CagA antibody-negative individuals from Costa Rica. All 26 of these samples had a Western-type cagA allele. Presence of serum CagA antibodies was correlated with a significantly higher load of H. pylori in the stool.

CONCLUSIONS

The stool-based ddPCR assays are a sensitive, noninvasive method for detection, quantification, and partial genotyping of H. pylori. The quantitative nature of ddPCR-based H. pylori detection revealed significant variation in bacterial load among individuals that correlates with presence of the cagA virulence gene. These stool-based ddPCR assays will facilitate future population-based epidemiologic studies of this important human pathogen.

Assessment of Risk and Sero-Prevalence of Helicobacter pylori Colonization among Remote Orang Asli Tribes in Peninsula Malaysia

The epidemiology of Helicobacter pylori (H. pylori) infection is related to human poverty with marked differences between developing and developed countries. Socioeconomic factors and living standards are the main determinants of the age-dependent acquisition rate of H. pylori, and consequently its prevalence. The aim of this study was to assess the risk and sero-prevalence of H. pylori colonization among Orang Asli in Peninsula Malaysia. This cross-sectional study was conducted on Orang Asli subjects in seven isolated settlements spanning across all three major tribes (Negrito, Proto Malay and Senoi) in Malaysia. Socio-demographic characteristics of the subjects were obtained through interview. Subjects were tested for H. pylori colonization based on CagA and whole cell (WC) antigen serological assays. A total of 275 subjects participated in this study. Among these subjects, 115 (44.7%) were H. pylori sero-positive with highest sero-prevalence among Negrito (65.7%). Among subjects who were H. pylori sero-positive, CagA sero positivity was also significantly higher among Negrito. The highest proportion of respondents reported to be H. pylori sero-positive was from age group 30 years old and below (57.9%), males (56.2%), Negrito (48.6%) and live in bamboo house (92.3%). The highest proportion of respondents reported to be CagA sero-positive was from age group 30 years old and below (41.4%), males (35.6%) and Negrito (48.6%). The results of this study demonstrate that H. pylori colonization can be related to age, gender, tribes and house materials and CagA sero-positive stain closely associated with age, gender and tribes.

Functional dyspepsia and dyspepsia associated with Helicobacter pylori infection: Do they have different clinical characteristics?

BACKGROUND

Helicobacter pylori causes motor, secretory, and inflammatory gastrointestinal disorders and therefore the term "functional" has been questioned when referring to dyspepsia associated with this bacterium. Patients with dyspepsia and Helicobacter pylori infection could have clinical characteristics that differentiate them a priori from those with true functional dyspepsia.

AIMS

To determine whether there are clinical differences between patients with functional dyspepsia and Helicobacter pylori-associated dyspepsia that enable their a priori identification and to know the prevalence of Helicobacter pylori infection in patients with functional dyspepsia.

PATIENTS AND METHODS

A total of 578 patients with dyspepsia with no significant lesions detectable through endoscopy were divided into 2 groups according to the presence of Helicobacter pylori. The clinical characteristics, medical history, comorbidities, and use of health resources were compared between the two groups. A sub-analysis pairing the groups by age and sex in a 1:1 ratio was carried out to reduce bias.

RESULTS

A total of 336 patients infected with Helicobacter pylori were compared with 242 non-infected patients. The prevalence of infection in the patients with dyspeptic symptoms and no endoscopically detectable lesions was 58%. The initial analysis showed that the cases with dyspepsia and Helicobacter pylori infection were more frequently associated with overweight, obesity, high blood pressure, diabetes mellitus, and metabolic syndrome, but the paired analysis nullified all these differences.

CONCLUSIONS

The patients with dyspepsia infected with Helicobacter pylori had similar clinical characteristics to the non-infected patients and could not be differentiated a priori. The prevalence of Helicobacter pylori infection in patients with functional dyspepsia was 58% and increased with age.

Relationship between gastrointestinal flora and chronic atrophic gastritis

Large amounts of intestinal flora are living in the gastrointestinal tract and have a close relationship with human health. The imbalance of gastrointestinal flora can lead to various gastrointestinal diseases, including chronic atrophic gastritis (CAG). CAG is a common gastrointestinal disease caused by a combination of many factors. In recent years, more and more studies have been performed to investigate the relationship between gastrointestinal flora and CAG. This paper summarizes their relationship in terms of the pathogenic mechanism and eradication of Helicobacter pylori, and the physiological function and anti-inflammatory mechanism of Lactobacillus and Bifidobacterium, with an aim to help better understand the pathogenesis and clinical treatment of CAG.

Meta-analysis of association between Helicobacter pylori infection and multiple sclerosis

Despite recent research focus on the association between Helicobacter pylori (H. pylori) infection and multiple sclerosis (MS) there is no consensus about the findings. To obtain a more comprehensive estimate of the association we conducted a meta-analysis to determine the prevalence of H. pylori infection in MS patients and healthy controls. Pubmed and EMBASE were searched to identify eligible studies. Nine studies were selected for inclusion, involving 2806 cases (1553 patients with MS and 1253 controls). Overall, the prevalence of H. pylori infection in MS patients was lower than that in control groups (24.66% vs. 31.84%, OR=0.69, 95% CI: 0.57-0.83, P<0.0001). Subgroup analysis revealed that the levels of H.pylori infection among MS patients were lower than for control subjects in Western countries (11.90% vs. 16.08%, OR=0.63, 95% CI: 0.43-0.91, P=0.01), but were not statistically significant in Eastern countries (39.39% vs. 43.82%, OR=0.79, 95% CI: 0.55-1.14, P=0.20). Our data show that H. pylori infection and MS is negatively correlated, especially in Western countries. Whether H. pylori infection is a protective factor against MS risk should thus be addressed in large-scale and prospective studies.

Identification of a Latin American-specific BabA adhesin variant through whole genome sequencing of Helicobacter pylori patient isolates from Nicaragua

Background

Helicobacter pylori (H. pylori) is one of the most common bacterial infections in humans and this infection can lead to gastric ulcers and gastric cancer. H. pylori is one of the most genetically variable human pathogens and the ability of the bacterium to bind to the host epithelium as well as the presence of different virulence factors and genetic variants within these genes have been associated with disease severity. Nicaragua has particularly high gastric cancer incidence and we therefore studied Nicaraguan clinical H. pylori isolates for factors that could contribute to cancer risk.

Methods

The complete genomes of fifty-two Nicaraguan H. pylori isolates were sequenced and assembled de novo, and phylogenetic and virulence factor analyses were performed.

Results

The Nicaraguan isolates showed phylogenetic relationship with West African isolates in whole-genome sequence comparisons and with Western and urban South- and Central American isolates using MLSA (Multi-locus sequence analysis). A majority, 77 % of the isolates carried the cancer-associated virulence gene cagA and also the s1/i1/m1 vacuolating cytotoxin, vacA allele combination, which is linked to increased severity of disease. Specifically, we also found that Nicaraguan isolates have a blood group-binding adhesin (BabA) variant highly similar to previously reported BabA sequences from Latin America, including from isolates belonging to other phylogenetic groups. These BabA sequences were found to be under positive selection at several amino acid positions that differed from the global collection of isolates.

Conclusion

The discovery of a Latin American BabA variant, independent of overall phylogenetic background, suggests hitherto unknown host or environmental factors within the Latin American population giving H. pylori isolates carrying this adhesin variant a selective advantage, which could affect pathogenesis and risk for sequelae through specific adherence properties.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-016-0619-y) contains supplementary material, which is available to authorized users.

Female gender and Helicobacter pylori infection, the most important predisposition factors in a cohort of gastric cancer: A longitudinal study

BACKGROUND

Gastric cancer (GC) is one of the most common Cancers in the world and Helicobacter pylori (HP) infection is considered a causative factor. The aim of this study was to determine the characteristics and the associated factors of (GC) in a small cohort.

METHODS

Overall, 54 patients with diagnosed gastric cancer were followed-up at the Department of Gastroenterology & Hepatology at Baqiyatallah University of Medical Sciences. 37 (68.5%) of them were positive for H pylori infection in histopathological evaluations. Univariate and multivariate regression analyses were used to determine the associations of demographic features and HP infection status with GC characteristics and prognosis.

RESULTS

Univariate analysis showed female gender (odds ratio (OR): 6.53; 95% confidence interval (95%CI): 1.59-26.8; P=0.008), and illiteracy (compared to intermediate education; OR: 5.9, 95%CI: 1.37-25.43; p=0.05) were associated significantly with higher rate of HP infection. After a mean±SD follow-up duration of 254±329 months, only female gender was significantly associated with HP infection in GC (OR:4.56; 95% CI: 1.0-21.76; P=0.05). H pylori positive patients had significantly higher grade of GC (OR: 3.97; 95% CI: 1.0-16.16; P=0.05), and a trend toward greater GC stage (OR: 4.46, 95% CI: 9.39-21.23; p=0.06). There was no association between survival rate and H pylori infection.

CONCLUSION

In the current study, we found a significant association of female gender with GN and an association of higher grade of GC with female gender. These findings may indicate a sex disparity in susceptibility to HP infection regarding GC future studies of larger populations are recommended.

Population, Epidemiological, and Functional Genetics of Gastric Cancer Candidate Genes in Peruvians with Predominant Amerindian Ancestry

BACKGROUND

Gastric adenocarcinoma is associated with chronic infection by Helicobacter pylori and with the host inflammatory response triggered by it, with substantial inter-person variation in the immune response profile due to host genetic factors.

AIM

To investigate the diversity of the proinflammatory genes IL8, its receptors and PTGS2 in Amerindians; to test whether candidate SNPs in these genes are associated with gastric cancer in an admixed population with high Amerindian ancestry from Lima, Peru; and to assess whether an IL8RB promoter-derived haplotype affects gene expression.

METHODS

We performed a Sanger-resequencing population survey, a candidate-gene association study (220 cases, 288 controls) and meta-analyses. We also performed an in vitro validation by a reporter gene assay of IL8RB promoter.

RESULTS

The diversity of the promoter of studied genes in Native Americans is similar to Europeans. Although an association between candidate SNPs and gastric cancer was not found in Peruvians, trend in our data is consistent with meta-analyses results that suggest PTGS2-rs689466-A is associated with H. pylori-associated gastric cancer in East Asia. IL8RB promoter-derived haplotype (rs3890158-A/rs4674258-T), common in Peruvians, was up-regulated by TNF-α unlike the ancestral haplotype (rs3890158-G/rs4674258-C). Bioinformatics analysis suggests that this effect stemmed from creation of a binding site for the FOXO3 transcription factor by rs3890158G>A.

CONCLUSIONS

Our updated meta-analysis reinforces the role of PTGS2-rs689466-A in gastric cancer in Asians, although more studies that control for ancestry are necessary to clarify its role in Latin Americans. Finally, we suggest that IL8RB-rs3890158G>A is a cis-regulatory SNP.

European Code against Cancer 4th Edition: Infections and Cancer

Of the 2,635,000 new cancer cases (excluding non-melanoma skin cancers) occurring in the European Union (EU) in 2012, it is estimated that approximately 185,000 are related to infection with human papillomaviruses (HPVs), hepatitis B and C viruses (HBV and HCV), and Helicobacter pylori (H. pylori). Chronic infection with these agents can lead to cancers of the cervix uteri, liver, and stomach, respectively. Chronic infection with HCV can also lead to B-cell non-Hodgkin lymphoma. Human immunodeficiency virus (HIV) infection continues to be of major public health importance in several EU countries and increases cancer risk via HIV-induced immunosuppression. The fourth edition of the European Code Against Cancer presents recommendations on effective and safe preventive interventions in order to reduce the risk of infection-related cancers in EU citizens. Based on current available evidence, the fourth edition recommends that parents ensure the participation of their children in vaccination programs against HBV (for newborns) and HPV (for girls). In the 'Questions and Answers' (Q&As) section about vaccination and infections in the website for the European Code Against Cancer, individuals who are at risk of chronic HBV or HCV are advised to seek medical advice about testing and obtaining treatment when appropriate. Individuals most at risk of HIV are advised to consult their doctor or healthcare provider to access counselling and, if needed, testing and treatment without delay. Information about H. pylori testing and treatment is also provided as testing might currently be offered in some high-risk areas in Europe. The rationale and supporting evidence for the recommendations on vaccination in the European Code Against Cancer, and for the main recommendations on vaccination and infection in the Q&As, are explained in the present review.

Identification of factors related with Helicobacter pylori infection in adults

AIM: To identify factors related with Helicobacter pylori (H. pylori) infection in the adult population.

METHODS: A total of 10000 adults who underwent physical examination at our hospital from January 2008 to January 2014 were retrospectively studied. The impact of clinical data for these patients such as age, sex, lifestyle, and different endoscopic lesions on H. pylori infection was investigated.

RESULTS: There was no significant difference in the distribution of gender or age group in the whole population (P > 0.05). The 18-25 age group had the lowest rate of H. pylori infection, while the 46-55 age group had the highest rate. High-salt diet, eating sweet food, frequent drinking of unclean water, history of gastric disease, and family history of gastric disease were significantly associated with H. pylori infection (P < 0.05), but eating smoked food, eating raw vegetables, irregular meals and other living habits had no obvious correlation with H. pylori infection (P > 0.05). H. pylori infection rate was significantly lower in reflux esophagitis than in the normal esophagus (P < 0.05). H. pylori infection rate was significantly higher in chronic atrophic inflammation associated with acute gastritis, gastric ulcer, and chronic atrophic gastritis than in the normal gastric mucosa (P < 0.05), and in duodenal ulcer and duodenitis than in the normal duodenum (P < 0.05).

CONCLUSION: Age and gender have a low degree of correlation with H. pylori infection in adults, while higher H. pylori infection rate is associated with bad habits and different endoscopic lesions.

Correlation of nodular gastritis with Helicobacter pylori infection

Nodular gastritis (NG) is a form of chronic Helicobacter pylori (H. pylori) associated gastritis affecting the gastric antrum, which is characterized endoscopically by the presence of small nodular lesions resembling gooseflesh. It is generally accepted that NG is characterized histologically by hyperplasia of lymphoid follicles. At present, there is a wide range of H. pylori infections in the world, and NG is an endoscopic sign of H. pylori infection. After H. pylori eradication therapy, the clinical manifestations, pathology and endoscopic performance of NG patients can be improved significantly. Therefore, H. pylori eradication should be performed as early as possible in NG patients. The research data about NG is still very limited. The relationship between NG as potentially precancerous lesions and gastroduodenal diseases is still a debate and needs to be further explored. Here we review the research progress in understanding the correlation between NG and H. pylori.

Helicobacter pylori Infection Induces Anemia, Depletes Serum Iron Storage, and Alters Local Iron-Related and Adult Brain Gene Expression in Male INS-GAS Mice

Iron deficiency anemia (IDA) affects > 500 million people worldwide, and is linked to impaired cognitive development and function in children. Helicobacter pylori, a class 1 carcinogen, infects about half of the world’s population, thus creating a high likelihood of overlapping risk. This study determined the effect of H. pylori infection on iron homeostasis in INS-GAS mice. Two replicates of INS-GAS/FVB male mice (n = 9-12/group) were dosed with H. pylori (Hp) strain SS1 or sham dosed at 6–9 weeks of age, and were necropsied at 27–29 weeks of age. Hematologic and serum iron parameters were evaluated, as was gene expression in gastric and brain tissues. Serum ferritin was lower in Hp SS1-infected mice than uninfected mice (p < 0.0001). Infected mice had a lower red blood cell count (p<0.0001), hematocrit (p < 0.001), and hemoglobin concentration (p <0.0001) than uninfected mice. Relative expression of gastric hepcidin antimicrobial peptide (Hamp) was downregulated in mice infected with Hp SS1 compared to sham-dosed controls (p<0.001). Expression of bone morphogenic protein 4 (Bmp4), a growth factor upstream of hepcidin, was downregulated in gastric tissue of Hp SS1-infected mice (p<0.001). Hp SS1-infected mice had downregulated brain expression of tyrosine hydroxylase (Th) (p = 0.02). Expression of iron-responsive genes involved in myelination (myelin basic protein (Mbp) and proteolipid protein 2 (Plp2)) was downregulated in infected mice (p = 0.001 and p = 0.02). Expression of synaptic plasticity markers (brain derived neurotrophic factor 3 (Bdnf3), Psd95 (a membrane associated guanylate kinase), and insulin-like growth factor 1 (Igf1)) was also downregulated in Hp SS1-infected mice (p = 0.09, p = 0.04, p = 0.02 respectively). Infection of male INS-GAS mice with Hp SS1, without concurrent dietary iron deficiency, depleted serum ferritin, deregulated gastric and hepatic expression of iron regulatory genes, and altered iron-dependent neural processes. The use of Hp SS1-infected INS-GAS mice will be an appropriate animal model for further study of the effects of concurrent H. pylori infection and anemia on iron homeostasis and adult iron-dependent brain gene expression.

Association between Helicobacter pylori infection and stroke: a meta-analysis of prospective observational studies

BACKGROUND

Some studies have suggested an association between Helicobacter pylori infection and the risk of stroke, but the relationship remains controversial. The aim of this study was to obtain a more comprehensive estimate of H. pylori on the risk of stroke by performing a meta-analysis.

METHODS

A computerized search of PubMed, EMBASE, and the Cochrane library (including CENTRAL) up to February 2014 was performed to identify eligible studies. Prospective studies reported that a multivariate-adjusted estimate for the association between H. pylori and stroke were included. A random-effects model was used to calculate the overall combined risk.

RESULTS

Ten prospective observational studies (6 cohort studies, 4 nested case-control, or case-cohort studies within cohort studies) were included in the meta-analysis. The overall combined odds ratio for H. infection and stroke was .96 (95% confidence interval, .78-1.14). Similar results were yielded in patients with cytotoxin-associated gene-A seropositive strains. The combined estimates were robust across sensitivity analyses and had no observed publication bias.

CONCLUSIONS

In conclusion, our formal meta-analysis indicated no strong association between H. pylori infection and stroke, neither in those with cytotoxin-associated gene-A-positive infection. We believe that future epidemiologic studies of H. pylori and stroke are unlikely to be fruitful.

The Serum Immunoglobulin G Glycosylation Signature of Gastric Cancer

Biomarkers may facilitate detection of gastric cancer at an earlier stage and reduce mortality. Here we sought to determine if the glycosylation profile of serum immunoglobulin G (IgG) could distinguish patients with non-atrophic gastritis (NAG), duodenal ulcer (DU) and gastric cancer (GC). Serum IgG was released and analyzed using nano-LC-TOF mass spectrometry. Statistically significant false discovery rate (FDR)-adjusted p-values were observed for 18 glycans, eight that differed significantly between NAG and GC, three that distinguished NAG from DU, and eight that differed between DU and GC. The IgG glycosylation signature may be useful as a predictive marker for gastric cancer.

Prevention strategies for gastric cancer: a global perspective

Despite the substantial burden of gastric cancer worldwide, population strategies for primary prevention have not been introduced in any country. Recognizing the causal role of Helicobacter pylori infection, there is increasing interest in population-based programs to eradicate the infection to prevent gastric cancer. Nonetheless, the paucity of available evidence on feasibility and effectiveness has prevented implementation of this approach. There are very few secondary prevention programs based on screening with endoscopy or radiography, notably in the Republic of Korea and Japan, two of the countries with the highest incidence rates of gastric cancer. In Korea, where the organized screening program is in place, survival rate of gastric cancer is as high as 67%. More research is needed to quantify the specific contribution of the screening program to observed declines in mortality rates. Gastric cancer screening is unlikely to be feasible in many Low-Middle Income Countries where the gastric cancer burden is high. Prevention strategies are still under development and the optimal approach may differ depending on local conditions and societal values. The present review gives an overview of the etiology and burden of the disease, and possible prevention strategies for countries and regions confronted with a significant burden of disease.

Helicobacter pylori infection in pediatrics

This review concerns important pediatric studies published from April 2013 to March 2014. New data on pathogenesis have demonstrated that Th1 type cytokine secretion at the gastric level is less intense in children compared with adults. They have also shown that the most significant risk factor for Helicobacter pylori infection is the parents' origin and frequency of childcare in settings with a high prevalence of infection. A new hypothesis on the positive relationship between childhood H. pylori infection and the risk of gastric cancer in adults has been suggested which calls for an implementation of preventive programs to reduce the burden of childhood H. pylori infection in endemic areas. Several studies have investigated the role of H. pylori infection in iron-deficiency anemia, and results support the role of the bacterium in this condition. Antibiotic resistance is an area of intense research with data confirming an increase in antibiotic resistance, and the effect of CYP2C19 genetic polymorphism on proton-pump inhibitor metabolism should be further investigated as cure rates are lower in extensive metabolizers. Studies confirmed that probiotic supplementation may have beneficial effects on eradication and therapy-related side effects, particularly diarrhea in children.

Epidemiology of Helicobacter pylori infection

Medline and PubMed databases were searched on epidemiology of Helicobacter pylori for the period of April 2013-March 2014. Several studies have shown that the prevalence of H. pylori is still high in most countries. In north European and North American populations, about one-third of adults are still infected, whereas in south and east Europe, South America, and Asia, the prevalence of H. pylori is often higher than 50%. H. pylori remains highly prevalent in immigrants coming from countries with high prevalence of H. pylori. However, the lower prevalence of infection in the younger generations suggests a further decline of H. pylori prevalence in the coming decades. Low socioeconomic conditions in childhood are confirmed to be the most important risk factors for H. pylori infection. Although the way the infection is transmitted is still unclear, interpersonal transmission appears to be the main route. Finally, H. pylori recurrence after successful eradication can still occur, but seems to be an infrequent event.

Prevention of Helicobacter pylori infection in childhood

Helicobacter pylori (H. pylori) infection is one of the most common infections worldwide. Although infection rates are falling in the developed and developing countries, H. pylori is still widespread in the world. This article has reviewed the important publications on H. pylori in childhood with a focus on its evolving transmission route and the source of infection and preventive strategies in childhood, PubMed was searched up to identify eligible studies. Relevant publications were searched using the following.

Virulence genes of Helicobacter pylori in the Dominican Republic

Although the incidence of gastric cancer in the Dominican Republic is not high, the disease remains a significant health problem. We first conducted a detailed analysis of Helicobacter pylori status in the Dominican Republic. In total, 158 patients (103 females and 55 males; mean age 47.1±16.2 years) were recruited. The status of H. pylori infection was determined based on four tests: rapid urease test, culture test, histological test and immunohistochemistry. The status of cagA and vacA genotypes in H. pylori was examined using PCR and gene sequencing. The overall prevalence of H. pylori infection was 58.9 %. No relationship was found between the H. pylori infection rate and the age range of 17-91 years. Even in the youngest group (patients aged <29 years), the H. pylori infection rate was 62.5 %. Peptic ulcer was found in 23 patients and gastric cancer was found in one patient. The H. pylori infection rate in patients with peptic ulcer was significantly higher than that in patients with gastritis (82.6 versus 54.5 %, P<0.01). The cagA-positive/vacA s1m1 genotype was the most prevalent (43/64, 67.2 %). Compared with H. pylori-negative patients, H. pylori-positive patients showed more severe gastritis. Furthermore, the presence of cagA was related to the presence of more severe gastritis. All CagA-positive strains had Western-type CagA. In conclusion, we found that H. pylori infection is a risk factor for peptic ulcer in the Dominican Republic. Patients with cagA-positive H. pylori could be at higher risk for severe inflammation and atrophy.

Gastric biopsies: the gap between evidence-based medicine and daily practice in the management of gastric Helicobacter pylori infection

BACKGROUND

Many consider histology to be the gold standard for Helicobacter pylori detection. Because the number and distribution of H pylori organisms vary, particularly in patients taking proton pump inhibitors (PPIs), the American Gastroenterological Association recommends discontinuing PPIs two weeks before endoscopy, and taking biopsies from both the body and antrum.

OBJECTIVE

To assess the influence of clinical practice on the histopathological detection of H pylori infection.

METHODS

Electronic patient records were evaluated for the sites of gastric sampling and PPI use at endoscopy. One hundred fifty cases with biopsies taken from both antrum and body were randomly selected for pathological re-review with special stains. The gastric regions sampled, H pylori distribution and influence of clinical factors on pathological interpretation were assessed.

RESULTS

Between 2005 and 2010, 10,268 biopsies were taken to detect H pylori. Only one region was sampled in 60% of patients (antrum 47%, body 13%). Re-review of biopsies taken from both antrum and body indicated that the correct regions were sampled in only 85 (57%) patients. Of these, 54 were H pylori positive and 96 were H pylori negative. H pylori was present in the antrum in only 15% of the patients and body only in 21%. Of 96 H pylori-negative patients, two were reinterpreted as positive. Forty-seven per cent of patients were taking PPIs at endoscopy, contributing to both false-negative and false-positive diagnoses.

CONCLUSION

Despite national and international guidelines for managing H pylori infection, the American Gastroenterological Association guidelines are infrequently adhered to, with PPIs frequently contributing to false diagnosis; sampling one region only increases the likelihood of missing active infection by at least 15%.

Helicobacter pylori eradication in the prevention of gastric cancer: are more trials needed?

The incidence of gastric cancer has decreased in much of the world, but gastric cancer remains the second leading cause of cancer death globally, and the burden is growing in many countries in East Asia and Latin America. Chronic infection with Helicobacter pylori is the dominant cause of gastric cancer, and two recent randomized trials showed that H. pylori eradication significantly decreased gastric cancer risk. Population screening and treating individuals for H. pylori also appears to be cost-effective. Nevertheless, current clinical guidelines differ as to whether asymptomatic adults should be screened and treated for H. pylori, and no countries have yet implemented eradication programs. Some of this inaction may reflect lingering doubts about the effectiveness of H. pylori eradication in preventing gastric cancer, but there is also uncertainty about possible risks of mass antibiotic treatment and its impact on gut flora. Appropriately designed studies will help address these issues and hasten the implementation of population-wide prevention programs.

Role of gene polymorphisms in gastric cancer and its precursor lesions: Current knowledge and perspectives in Latin American countries

Latin America shows one of the highest incidence rates of gastric cancer in the world, with variations in mortality rates among nations or even within countries belonging to this region. Gastric cancer is the result of a multifactorial complex process, for which a multistep model of carcinogenesis is currently accepted. Additionally to the infection with Helicobacter pylori, that plays a major role, environmental factors as well as genetic susceptibility factors are significant players at different stages in the gastric cancer process. The differences in population origin, demographic structure, socio-economic development, and the impact of globalization lifestyles experienced in Latin America in the last decades, all together offer opportunities for studying in this context the influence of genetic polymorphisms in the susceptibility to gastric cancer. The aim of this article is to discuss current trends on gastric cancer in Latin American countries and to review the available published information about studies of association of gene polymorphisms involved in gastric cancer susceptibility from this region of the world. A total of 40 genes or genomic regions and 69 genetic variants, 58% representing markers involved in inflammatory response, have been used in a number of studies in which predominates a low number of individuals (cases and controls) included. Polymorphisms of IL-1B (-511 C/T, 14 studies; -31 T/C, 10 studies) and IL-1RN (variable number of tandem repeats, 17 studies) are the most represented ones in the reviewed studies. Other genetic variants recently evaluated in large meta-analyses and associated with gastric cancer risk were also analyzed in a few studies [e.g., prostate stem cell antigen (PSCA), CDH1, Survivin]. Further and better analysis centered in gene polymorphisms linked to other covariates, epidemiological studies and the information provided by meta-analyses and genome-wide association studies should help to improve our understanding of gastric cancer etiology in order to develop appropriate health programs in Latin America.

Coffee intake and gastric cancer risk: the Singapore Chinese health study

BACKGROUND

Despite experimental evidence showing chemopreventive effects of coffee-related compounds on gastric carcinogenesis, epidemiologic studies generally do not support coffee-gastric cancer associations. Observational data are lacking among high-risk populations with sufficient regular coffee consumption.

METHODS

We examined the association between caffeinated coffee intake and gastric cancer risk in a population-based cohort that enrolled 63,257 Chinese men and women ages 45 to 74 years between 1993 and 1998 in Singapore. Incident gastric cancer cases (n = 647) were identified after a mean follow-up of 14.7 years. Biomarkers of Helicobacter pylori (H. pylori) infection were measured in a subset of gastric cancer cases with blood collected before cancer diagnosis and their matched controls.

RESULTS

In the total cohort, daily versus nondaily coffee intake was associated with a statistically nonsignificant decrease in gastric cancer risk [HR = 0.85; 95% confidence interval (CI), 0.69-1.04]. In women, the inverse association strengthened and reached statistical significance (HR = 0.63; 95% CI, 0.46-0.87). In analyses restricted to never smokers and nondrinkers of alcohol, inverse associations strengthened in the total cohort (HR = 0.69; 95% CI, 0.52-0.91) and in women (HR = 0.52; 95% CI, 0.37-0.74). There was no coffee-gastric cancer risk association among men, regardless of smoking status or alcohol consumption. Similar results were observed in the nested case-control study after adjustment for H. pylori infection.

CONCLUSION

Daily coffee consumption may reduce the risk of gastric cancer in high-risk populations, especially among women.

IMPACT

Research aimed at identifying the compounds in coffee that may protect against gastric carcinogenesis is warranted.

Serum glycan signatures of gastric cancer

Glycomics, a comprehensive study of glycans expressed in biologic systems, is emerging as a simple yet highly sensitive diagnostic tool for disease onset and progression. This study aimed to use glycomics to investigate glycan markers that would differentiate patients with gastric cancer from those with nonatrophic gastritis. Patients with duodenal ulcer were also included because they are thought to represent a biologically different response to infection with Helicobacter pylori, a bacterial infection that can cause either gastric cancer or duodenal ulcer. We collected 72 serum samples from patients in Mexico City that presented with nonatrophic gastritis, duodenal ulcer, or gastric cancer. N-glycans were released from serum samples using the generic method with PNGase F and were analyzed by matrix-assisted laser desorption/ionization Fourier transform-ion cyclotron resonance mass spectrometry. The corresponding glycan compositions were calculated based on accurate mass. ANOVA-based statistical analysis was performed to identify potential markers for each subgroup. Nineteen glycans were significantly different among the diagnostic groups. Generally, decreased levels of high-mannose-type glycans, glycans with one complex type antenna, bigalactosylated biantennary glycans, and increased levels of nongalactosylated biantennary glycans were observed in gastric cancer cases. Altered levels of serum glycans were also observed in duodenal ulcer, but differences were generally in the same direction as gastric cancer. Serum glycan profiles may provide biomarkers to differentiate gastric cancer cases from controls with nonatrophic gastritis. Further studies will be needed to validate these findings as biomarkers and identify the role of protein glycosylation in gastric cancer pathology.

How antibiotic resistances could change Helicobacter pylori treatment: A matter of geography?

Therapeutic management of Helicobacter pylori (H. pylori) remains an unsolved issue. Indeed, no therapeutic regimen is able to cure the infection in all treated patients, and in many the infection persists despite the administration of several consecutive standard therapies. Although antibiotic resistance reports describe alarming results, the outcome of therapeutic regimens does not seem to parallel this scenario in most cases, since a successful performance is often reached in more than 80% of cases. However, the phenomenon of increasing antibiotic resistance is being closely studied, and the results show controversial aspects even in the same geographic area. For the continents of Europe, America, Asia, Africa, and Oceania, minimal and maximal values of resistance to the main antibiotics (clarithromycin, amoxicillin, metronidazole, and levofloxacin) feature wide ranges in different countries. The real enigma is therefore linked to the several different therapeutic regimens, which show results that often do not parallel the in vitro findings even in the same areas. A first aspect to be emphasized is that some regimens are limited by their use in very small geographic districts. Moreover, not all therapeutic trials have considered bacterial and host factors affecting the therapeutic outcome. The additional use of probiotics may help to reduce adverse events, but their therapeutic impact is doubtful. In conclusion, the “ideal therapy”, paradoxically, appears to be a “utopia”, despite the unprecedented volume of studies in the field and the real breakthrough in medical practice made by the discovery and treatment of H. pylori. The ample discrepancies observed in the different areas do not encourage the development of therapeutic guidelines that could be valid worldwide. On these bases, one of the main challenges for the future might be identifying a successful solution to overcome antibiotic resistances. In this context, geography must be considered a relevant matter.

High Seroprevalence of Helicobacter Pylori Infection in Inmates: A Case Control Study in a Northern Mexican City

Background

The epidemiology of Helicobacter pylori infection in inmates has not been previously studied. Therefore, we determine the seroepidemiology of H. pylori infection in inmates.

Methods

Through a case-control study, inmates from a state correctional facility in Durango, Mexico and subjects without incarceration of the same city were examined for the presence of anti-H. pylori IgG antibodies using enzyme-linked immunoassays. Seroprevalence association with socio-demographic, incarceration, clinical and behavioral characteristics of the inmates was also investigated.

Results

Antibodies to H. pylori were found in 140 (83.3%) of 168 inmates and in 101 (60.1%) of 168 controls. Seroprevalence of anti-H. pylori IgG antibodies was significantly higher in inmates than in controls (OR = 3.32; 95% CI: 1.93 - 5.71; P = 0.000002). The seroprevalence of H. pylori infection was not influenced by gender, age, or socioeconomic status of inmates. Seropositivity to H. pylori was found in 3 of 3 inmates with peptic ulcer and in 1 of 2 inmates with gastritis. The seroprevalence of H. pylori exposure was high regardless the jail section, duration (years) in incarceration and number of incarcerations. Multivariate analysis revealed that H. pylori exposure was positively associated with having tattoos (OR = 3.34; 95% CI: 1.14 - 9.70; P = 0.02), and negatively associated with drug abuse (OR = 0.28; 95% CI: 0.11 - 0.70; P = 0.007).

Conclusions

Seroprevalence of H. pylori exposure in inmates is higher than those found in non-incarcerated people and other populations in the region. Results indicate that inmates may represent a new risk group for H. pylori exposure. Results warrant for further research on the potential role of incarceration and behavioral features of inmates for H. pylori infection.

Diagnosis and epidemiology of Helicobacter pylori infection

A limited amount of new information was published in the field of diagnosis and epidemiology of Helicobacter pylori this last year. Besides some improvement in current tests, it is interesting to note the attempts to identify severe disease, for example gastric cancer, by breath analysis using nanomaterial-based sensors. In contrast, the predictive value for gastric cancer and atrophy of pepsinogen determinations was found inadequate. Prevalence studies of H. pylori infection have been carried out in adults and children around the world in the general population but also in specific communities. The usual risk factors were found. In addition, a Japanese study highlighted the role of grandmothers in the familial transmission of H. pylori. A study showed that the infection may not always readily establish itself in children, given the number of transient infections observed. It was also noted that after eradication, a first-year relapse is likely to be a recurrence of the previous infection, while later on it is probably a reinfection with a new strain.

Contaminated water as a source of Helicobacter pylori infection: A review

Over the preceding years and to date, the definitive mode of human infection by Helicobacter pylori has remained largely unknown and has thus gained the interest of researchers around the world. Numerous studies investigated possible sources of transmission of this emerging carcinogenic pathogen that colonizes >50% of humans, in many of which contaminated water is mentioned as a major cause. The infection rate is especially higher in developing countries, where contaminated water, combined with social hardships and poor sanitary conditions, plays a key role. Judging from the growing global population and the changing climate, the rate is expected to rise. Here, we sum up the current views of the water transmission hypothesis, and we discuss its implications.

Association of a probiotic to a Helicobacter pylori eradication regimen does not increase efficacy or decreases the adverse effects of the treatment: a prospective, randomized, double-blind, placebo-controlled study

Background

The treatment for the eradication of Helicobacter pylori (H. pylori) is complex; full effectiveness is rarely achieved and it has many adverse effects. In developing countries, increased resistance to antibiotics and its cost make eradication more difficult. Probiotics can reduce adverse effects and improve the infection treatment efficacy.

If the first-line therapy fails a second-line treatment using tetracycline, furazolidone and proton-pump inhibitors has been effective and low cost in Brazil; however it implies in a lot of adverse effects. The aim of this study was to minimize the adverse effects and increase the eradication rate applying the association of a probiotic compound to second-line therapy regimen.

Methods

Patients with peptic ulcer or functional dyspepsia infected by H. pylori were randomized to treatment with the furazolidone, tetracycline and lansoprazole regimen, twice a day for 7 days. In a double-blind study, patients received placebo or a probiotic compound (Lactobacillus acidophilus, Lactobacillus rhamnosus, Bifidobacterium bifidum and Streptococcus faecium) in capsules, twice a day for 30 days. A symptom questionnaire was administered in day zero, after completion of antibiotic therapy, after the probiotic use and eight weeks after the end of the treatment. Upper digestive endoscopy, histological assessment, rapid urease test and breath test were performed before and eight weeks after eradication treatment.

Results

One hundred and seven patients were enrolled: 21 men with active probiotic and 19 with placebo plus 34 women with active probiotic and 33 with placebo comprising a total of 55 patients with active probiotic and 52 with placebo. Fifty-one patients had peptic ulcer and 56 were diagnosed as functional dyspepsia. The per-protocol eradication rate with active probiotic was 89.8% and with placebo, 85.1% (p = 0.49); per intention to treat, 81.8% and 79.6%, respectively (p = 0.53). The rate of adverse effects at 7 days with the active probiotic was 59.3% and 71.2% with placebo (p = 0.20). At 30 days, it was 44.9% and 60.4%, respectively (p = 0.08).

Conclusions

The use of this probiotic compound compared to placebo in the proposed regimen in Brazilian patients with peptic ulcer or functional dyspepsia showed no significant difference in efficacy or adverse effects.

Trial registration

Current Controlled Trials ISRCTN04714018

Association of a probiotic to a Helicobacter pylori eradication regimen does not increase efficacy or decreases the adverse effects of the treatment: a prospective, randomized, double-blind, placebo-controlled study

Internet websites are a resource for patients seeking information about probiotics. We examined a sample of 71 websites presenting probiotic information. We found that descriptions of benefits far outnumbered descriptions of risks and commercial websites presented significantly fewer risks than noncommercial websites. The bias towards the presentation of therapeutic benefits in online content suggests that patients are likely interested in using probiotics and may have unrealistic expectations for therapeutic benefit. Gastroenterologists may find it useful to initiate conversations about probiotics within the context of a comprehensive health management plan and should seek to establish realistic therapeutic expectations with their patients.