Non-invasive genotyping of Helicobacter pylori cagA, vacA, and hopQ from asymptomatic children

Helicobacter pylori Outer Membrane Proteins and Virulence Factors: Potential Targets for Novel Therapies and Vaccines

Helicobacter pylori is a gastric oncopathogen that infects over half of the world's human population. It is a Gram-negative, microaerophilic, helix-shaped bacterium that is equipped with flagella, which provide high motility. Colonization of the stomach is asymptomatic in up to 90% of people but is a recognized risk factor for developing various gastric disorders such as gastric ulcers, gastric cancer and gastritis. Invasion of the human stomach occurs via numerous virulence factors such as CagA and VacA. Similarly, outer membrane proteins (OMPs) play an important role in H. pylori pathogenicity as a means to adapt to the epithelial environment and thereby facilitate infection. While some OMPs are porins, others are adhesins. The epithelial cell receptors SabA, BabA, AlpA, OipA, HopQ and HopZ have been extensively researched to evaluate their epidemiology, structure, role and genes. Moreover, numerous studies have been performed to seek to understand the complex relationship between these factors and gastric diseases. Associations exist between different H. pylori virulence factors, the co-expression of which appears to boost the pathogenicity of the bacterium. Improved knowledge of OMPs is a major step towards combatting this global disease. Here, we provide a current overview of different H. pylori OMPs and discuss their pathogenicity, epidemiology and correlation with various gastric diseases.

Infiltration to infection: key virulence players of Helicobacter pylori pathogenicity

PURPOSE

This study aims to comprehensively review the multifaceted factors underlying the successful colonization and infection process of Helicobacter pylori (H. pylori), a prominent Gram-negative pathogen in humans. The focus is on elucidating the functions, mechanisms, genetic regulation, and potential cross-interactions of these elements.

METHODS

Employing a literature review approach, this study examines the intricate interactions between H. pylori and its host. It delves into virulence factors like VacA, CagA, DupA, Urease, along with phase variable genes, such as babA, babC, hopZ, etc., giving insights about the bacterial perspective of the infection The association of these factors with the infection has also been added in the form of statistical data via Funnel and Forest plots, citing the potential of the virulence and also adding an aspect of geographical biasness to the virulence factors. The biochemical characteristics and clinical relevance of these factors and their effects on host cells are individually examined, both comprehensively and statistically.

RESULTS

H. pylori is a Gram-negative, spiral bacterium that successfully colonises the stomach of more than half of the world's population, causing peptic ulcers, gastric cancer, MALT lymphoma, and other gastro-duodenal disorders. The clinical outcomes of H. pylori infection are influenced by a complex interplay between virulence factors and phase variable genes produced by the infecting strain and the host genetic background. A meta-analysis of the prevalence of all the major virulence factors has also been appended.

CONCLUSION

This study illuminates the diverse elements contributing to H. pylori's colonization and infection. The interplay between virulence factors, phase variable genes, and host genetics determines the outcome of the infection. Despite biochemical insights into many factors, their comprehensive regulation remains an understudied area. By offering a panoramic view of these factors and their functions, this study enhances understanding of the bacterium's perspective, i.e. H. pylori's journey from infiltration to successful establishment within the host's stomach.

Reactive Oxygen Species and H. pylori Infection: A Comprehensive Review of Their Roles in Gastric Cancer Development

Gastric cancer (GC) is the fifth most common cancer worldwide and makes up a significant component of the global cancer burden. Helicobacter pylori (H. pylori) is the most influential risk factor for GC, with the International Agency for Research on Cancer classifying it as a Class I carcinogen for GC. H. pylori has been shown to persist in stomach acid for decades, causing damage to the stomach's mucosal lining, altering gastric hormone release patterns, and potentially altering gastric function. Epidemiological studies have shown that eliminating H. pylori reduces metachronous cancer. Evidence shows that various molecular alterations are present in gastric cancer and precancerous lesions associated with an H. pylori infection. However, although H. pylori can cause oxidative stress-induced gastric cancer, with antioxidants potentially being a treatment for GC, the exact mechanism underlying GC etiology is not fully understood. This review provides an overview of recent research exploring the pathophysiology of H. pylori-induced oxidative stress that can cause cancer and the antioxidant supplements that can reduce or even eliminate GC occurrence.

The Importance of Accurate Early Diagnosis and Eradication in Helicobacter pylori Infection: Pictorial Summary Review in Children and Adults

Among the most widespread childhood infections, Helicobacter pylori (H. pylori) develops potentially life-threatening conditions in adults if not appropriately treated. Helicobacter pylori is a common human pathogen that was first described in the stomach many years ago. The discovery of H. pylori was crucial in gastroenterology; this bacterium is associated with chronic gastritis, peptic ulcers, gastric cancer, and lymphoid tissue lymphoma related to the gastric mucosa. Studies published so far estimate that approximately 10% of subjects infected with H. pylori develop a peptic ulcer, and 1-3% of subjects develop gastric cancer. The clinical manifestations are variable and characteristically depend on the individual factors of the host. Various methods of detection and diagnosis of H. pylori infection have been developed, each with advantages, disadvantages, and/or limitations. Available diagnostic tests are usually performed using invasive (endoscopy, biopsy, rapid urease test, cultures, and molecular tests) and noninvasive methods (urea breath test, stool antigen examination, and serological and molecular tests). Although there is extensive accessibility for diagnosing and treating H. pylori infection, the prevalence of antibiotic resistance is not negligible. Thus, numerous studies and meta-analyses are focused on a new orientation of gastroenterologists in diagnosing and treating H. pylori infections. A fascinating perspective hypothesis is the administration of probiotics to reduce H. pylori adhesion to gastric epithelial cells, preventing H. pylori colonization, especially in children, or reinfection with H. pylori in high-risk adult patients.

DNMT1 Gene Expression in Patients with Helicobacter pylori Infection

DNMT1, as a critical enzyme affecting epigenetics through methylation of DNA cytosine-rich sequences, regulates gene expression. Exterior factors including long-term infections, in this study Helicobacter pylori infection, could change host cells' epigenetics by affecting DNMT1 gene expression. This study investigated the statistical correlation between H. pylori virulence genes and DNMT1 gene expression in gastric antral epithelial cells of gastric adenocarcinoma and gastritis patients. In a case-control study, 50 and 53 gastritis and gastric adenocarcinoma antral biopsies, including 23 and 21 patients with H. pylori infection, respectively, were collected from hospitals in the west of Iran. Having extracted total RNA from gastric biopsy samples, cDNA was synthesized and virulence genes of H. pylori were detected by using the PCR method. Relative real-time RT PCR was used to detect ΔΔCt fold changes of the DNMT1 gene expression in divided groups of patients based on H. pylori infection and clinical manifestations. The results showed that along with increasing patients' age, the DNMT1 gene expression will increase in gastric antral epithelial cells of gastric cancer patients (P ≤ 0.05). On the other hand, the biopsy samples with infection of H. pylori cagA, cagY, and cagE genotypes revealed a direct correlation along with increased DNMT1 gene expression. This study revealed the correlations of H. pylori cag pathogenicity island genes with increased DNMT1 gene expression.

ptk2 and mt2a Genes Expression in Gastritis and Gastric Cancer Patients with Helicobacter pylori Infection

BACKGROUND

ptk2 and mt2a genes contribute to the cell cycle during proliferation and apoptosis, respectively. Designing a case-control study including gastric adenocarcinoma and gastritis patients with and without Helicobacter pylori infection would lead to determinate of the correlations between ptk2 and mt2a genes expression with H. pylori infection in gastric antral epithelial cells.

METHODS

Overall, 50 and 30 gastric antral biopsy samples of gastric cancer (case group) and gastritis (control group) patients were included into study, respectively. All biopsy samples were collected considering the exclusion criteria including patients with a history of consumption of tobacco, alcohol, and anti-H. pylori drugs. Each patient group is divided into with and without H. pylori infection to detect cDNA fold changes of ptk2 and mt2a genes by using Real Time RT PCR. Furthermore, the presence of H. pylori virulence genes was detected directly by using specific primers and simple PCR on cDNA synthesized from total RNA of gastric antral biopsy samples.

RESULTS

A negative correlation was revealed between age and clinical manifestations with the ΔCt value of the ptk2 gene (P < 0.05). The H. pylori iceA1/2 and cagE genes revealed positive and negative correlations with the ΔCt value of the ptk2 gene (P < 0.05), respectively. Furthermore, a weak correlation was detectable between H. pylori babA2/B, oipA, and cagY genes and the ΔCt value of the mt2a gene in gastric antral epithelial cells of patients (P < 0.1).

CONCLUSIONS

The results of the current study opened a view for more investigation on the stunning roles of H. pylori infection in clinical outcomes through mt2a and ptk2 gene expression in gastric antral epithelial cells.

Genotyping Helicobacter pylori and fgf7 gene expression in gastric cancer

BACKGROUND

Helicobacter pylori as the causative agent of the most common chronic bacterial infectious disease in human still involves a range of clinical challenging complications. In this meantime, the survey of the interaction between H. pylori virulence genes expression and its consequences on gastric antral epithelial cells is Controversial. This study surveyed the correlations between H. pylori cag Pathogenicity Island and virulence factors genes with Fgf7 gene expression as an angiogenic factor in developing gastric cancer in gastric antral epithelial cells of patients with H. pylori infection.

METHOD

Gastric antral biopsy samples collected from patients out of exclusion criteria, including consumption of tobacco, alchohol and anti-H. pylori drugs, were categorized into gastric cancer (case group n:53) and gastritis (control group n:50) with and without H. pylori infection to detect changes in cDNA of fgf7 in gastric antral epithelial cells by using Real Time RT PCR. Extracted total RNA from gastric antral biopsy samples was used to synthesize cDNA for real time PCR. Furthermore, the cDNA of H. pylori cag Pathogenicity Island and other virulence factors genes were detected by using specific designed primers and simple PCR.

RESULTS

Fgf7 gene expression revealed a significantly increase in gastric antral epithelial cells of gastric cancer and H. pylori-positive patients in contrast with gastritis and H. pylori-negative patients (p < 0.05). In the meanwhile, cag Pathogenicity Island and hopQ genotypes showed a positive correlation with Fgf7 gene expression (fold changes of cDNA) in gastric antral epithelial cells (p < 0.05).

CONCLUSION

This study revealed an obvious correlation between Fgf7 gene expression in gastric antral epithelial cells of patients with H. pylori carcinogenic genotypes infection and some host factors including age.

Helicobacter pylori-Mediated Oxidative Stress and Gastric Diseases: A Review

Gastric cancer is considered to be a type of gastrointestinal tumor and is mostly accompanied by Helicobacter pylori (HP) infection at the early stage. Hence, the long-term colonization of the gastric mucosa by HP as a causative factor for gastrointestinal diseases cannot be ignored. The virulence factors secreted by the bacterium activate the signaling pathway of oxidative stress and mediate chronic inflammatory response in the host cells. The virulence factors also thwart the antibacterial effect of neutrophils. Subsequently, DNA methylation is induced, which causes continuous cell proliferation and evolution toward low-grade-differentiated gastric cells. This process provides the pathological basis for the occurrence of progressive gastric cancer. Therefore, this review aims to summarize the oxidative stress response triggered by HP in the gastric mucosa and the subsequent signaling pathways. The findings are expected to help in the formulation of new targeted drugs for preventing the occurrence of early gastric cancer and its progression to middle and advanced cancer.

Sirt3, 6, and 7 Genes Expression in Gastric Antral Epithelial Cells of Patients with Helicobacter pylori Infection

Sirtuins, known as the intracellular acylation enzymes, play a major role in regulating the cell's physiological activities. The relevant studies have shown diversely sirtuin genes expression in various cancers in humans. This study has surveyed the transcription of sirt3, 6, and 7 genes in gastric antral epithelial cells (GAECs) of gastritis and gastric adenocarcinoma patients with and without Helicobacter pylori infection. First of all, a case-control study was conducted, including 50 and 53 gastric antral biopsy samples collected from gastritis and gastric adenocarcinoma patients with and without H. pylori infection referred to hospitals of Sanandaj City during 2018-2019. Total RNAs were extracted from biopsy samples, then cDNAs were synthesized by using TaKaRa kits. Quality essay of H. pylori virulence genes expression and relative quantitative essay of sirt3, 6, and 7 genes expressions in gastric antral biopsy samples were performed using the real-time RT-PCR method. The statistical analysis showed the significant correlations between H. pylori vacA s1m2 and sabA cDNAs with sirt3 geneś expression in GAECs (P < 0.05, 0.05 respectively). In addition, sirt6 gene's expression decreased along increasing age in gastric adenocarcinoma patients (P < 0.05). The samples of gastritis patients with gastric antral epithelial biopsy containing H. pylori hopQII, oipA, and sabB cDNA showed an increased amount of sirt7 genes expression (P < 0.05, 0.05, and 0.05 respectively). In conclusion, the H. pylori virulence genes expression and increasing age of patients showed the significant correlations with sirt3, 6, and 7 genes expressions in GAECs of gastric and gastric cancer patients.

Methods for detection of Helicobacter pylori from stool sample: current options and developments

Accurate detection of Helicobacter pylori infection and determination of antibiotics have significant meaning in clinical practice. The detection methods can be categorized into two types, invasive and non-invasive, but nowadays we use the urease breath test most frequently which is non-invasive. However, many developing countries cannot meet the requirements for having specialized equipment and they lack trained personnel. Also, for the children, it is difficult to make them cooperate for the test. Methods that detect Helicobacter pylori from stool sample can be a promising alternative for detection used in children and mass screening. Stool antigen tests have several advantages such as rapidity, simplicity, and cheapness, though their results may be influenced by the heterogenicity of antigens, the nature of biochemical techniques, and the amount of antigen presented in the stool. PCR-based methods can specifically detect Helicobacter pylori infection and antibiotic resistance by targeting specific gene sequence, but they also are limited by the requirements of facilities and experts, the existence of inhibitory substance, and interference from the dead bacteria. Some novel methods also deserve our attention. Here we summarized the results of researches about methods using stool sample and we hope our work can help clinicians choose the appropriate test in clinical practice.

Transcriptional Profile of Helicobacter pylori Virulence Genes in Patients with Gastritis and Gastric Cancer

Introduction

Numerous molecular epidemiology studies have been performed about the frequency of Helicobacter pylori virulence genes in patients with H. pylori infection so far. This study was conducted to detect transcriptional profile by cDNA of H. pylori virulence genes in gastric biopsy samples of gastritis and gastric carcinoma patients.

Materials and Methods

In a case-control study, based on the prevalence of gastritis and gastric cancer in Sanandaj city during 2018 and 2019, 23 and 11 gastric antral biopsy samples with H. pylori infection were collected from gastritis and gastric carcinoma patients by the consecutive and available sampling method. Pathological characters, including tumor grades and tumor areas for gastric carcinoma biopsy samples prepared from gastric cancer areas, were determined by the pathologist. Total RNA of gastric antral biopsy samples was extracted, and their cDNA was synthesized by TaKaRa kit. H. pylori virulence genes' cDNA using specific primers and PCR was detected. This study's results were analyzed by SPSS version 25 and statics chi-square tests for determination of relationship and correlation between cDNAs of H. pylori transcriptional profile and clinical outcomes of H. pylori infection, including gastritis, gastric carcinoma, tumor grades, and tumor area.

Results

The positive statistical correlations were observed between transcripts of cagA, cagA-EPIYAC, cagE, and cagY genes and H. pylori infection clinical outcomes (P < 0.05).

Conclusion

Detection of the H. pylori virulence genes' cDNA in gastric biopsy samples can help provide the prognosis of clinical outcomes.

ZAK Gene Expression in Patients with Helicobacter pylori Infection

BACKGROUND

ZAK protein is a member of the MLK family proteins defined as mediators in the cell cycle. A survey of ZAK gene expression in gastric antral epithelial cells (GAECs) of gastritis and gastric adenocarcinoma patients with Helicobacter pylori genotypes infection can elucidate carcinogenesis of H. pylori genotypes.

METHODS

In a case-control study, ZAK gene expression was evaluated in GAECs biopsy samples of gastritis and gastric adenocarcinoma patients with (n 23, 21) and without H. pylori infection (n 27, 32), respectively. Total RNA was extracted from each gastric antral biopsy samples and cDNA synthesized by using Takara kits. H. pylori virulence genes֝ cDNA were detected by traditional PCR and specific primers. The ZAK gene expression was measured using the relative Real-Time RT PCR.

RESULTS

The prevalence of gastric adenocarcinoma was the highest in man and 61-85 aged groups (p < .05). There was no significant correlation between the prevalence of H. pylori infection and patients' demographic groups. This study showed that ZAK gene overexpression gradually increases with increasing age and tumor grade among gastric adenocarcinoma patients. The gastric antral biopsy samples with H. pylori vacA s1m2 genotype infection showed a weak correlation with ZAK gene overexpression (p < .1).

CONCLUSION

ZAK gene expression was higher in GAECs of gastritis cancer than in gastric adenocarcinoma, indicating the protective effect of ZAK against gastric cancer (p < .005). Reducing ZAK gene expression shows the negative correlations with H. pylori infection and gastric adenocarcinoma.

Helicobacter pylori Virulence Factors-Mechanisms of Bacterial Pathogenicity in the Gastric Microenvironment

Gastric cancer constitutes one of the most prevalent malignancies in both sexes; it is currently the fourth major cause of cancer-related deaths worldwide. The pathogenesis of gastric cancer is associated with the interaction between genetic and environmental factors, among which infection by Helicobacter pylori (H. pylori) is of major importance. The invasion, survival, colonization, and stimulation of further inflammation within the gastric mucosa are possible due to several evasive mechanisms induced by the virulence factors that are expressed by the bacterium. The knowledge concerning the mechanisms of H. pylori pathogenicity is crucial to ameliorate eradication strategies preventing the possible induction of carcinogenesis. This review highlights the current state of knowledge and the most recent findings regarding H. pylori virulence factors and their relationship with gastric premalignant lesions and further carcinogenesis.

Effects of Concurrent Omega-3 and Cranberry Juice Consumption Along with Standard Antibiotic Therapy on the Eradication of Helicobacter pylori, Gastrointestinal Symptoms, Some Serum Inflammatory and Oxidative Stress Markers in Adults with Helicobacter pylori Infection: A Study Protocol for a Randomized Controlled Trial

BACKGROUND

It seems alternative treatments such as antioxidant intervention and anti-inflammatory intervention adjuvant to antibiotic regimens may enhance cancer prevention approaches and decrease adverse side effects related to therapeutic antibiotic regimens. So, we will evaluate the effects of concurrent omega-3 and cranberry juice supplementation along with standard antibiotic therapy on the eradication of Helicobacter pylori, gastrointestinal symptoms, some serum inflammatory and oxidative stress markers in adults with HP infection.

METHODS

We will conduct a 4-week double-blinded randomized clinical trial. The subjects will be randomly stratified according to sex and BMI using a permuted block randomization procedure by Random Allocation Software (RAS). They will be assigned to one of the four study groups: (1) cranberry juice fortified with omega-3 Intervention (n=23), (2) cranberry juice intervention group (n=23), (3) placebo beverage fortified with omega-3 intervention group (n=23), and (4) placebo beverage intervention (control group) (n=23). All statistical analyses will be performed using IBM SPSS Statistics software.

DISCUSSION

A combination of alternative therapies may have a synergistic effect compared to a single approach. It could potentially be more effective in promoting the efficacy of standard antibiotic therapy in eradicating HP infection.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (IRCT20151128025274N3, www.irct.ir/trial/28997).

TRIAL STATUS

This study is in the early stages of sampling.

Helicobacter pylori virulence genes

Helicobacter pylori (H. pylori) is one of the most important human pathogens, infecting approximately half of the global population. Despite its high prevalence, only a subset of H. pylori infected individuals develop serious gastroduodenal pathology. The pathogenesis of H. pylori infection and disease outcome is thus thought to be mediated by an intricate interplay between host, environmental and bacterial virulence factors. H. pylori has adapted to the harsh milieu of the human stomach through possession of various virulence genes that enable survival of the bacteria in the acidic environment, movement towards the gastric epithelium, and attachment to gastric epithelial cells. These virulence factors enable successful colonization of the gastric mucosa and sustain persistent H. pylori infection, causing chronic inflammation and tissue damage, which may eventually lead to the development of peptic ulcers and gastric cancer. Numerous studies have focused on the prevalence and role of putative H. pylori virulence genes in disease pathogenesis. While several virulence factors with various functions have been identified, disease associations appear to be less evident, especially among different study populations. This review presents key findings on the most important H. pylori virulence genes, including several bacterial adhesins and toxins, in children and adults, and focuses on their prevalence, clinical significance and potential relationships.

Expression of tryptophan hydroxylase in gastric mucosa in symptomatic and asymptomatic Helicobacter pylori infection

INTRODUCTION

Helicobacter pylori infection induces clinical symptoms in 15-20% of subjects, and the reason for this variation is still not clear. The aim of the present study is to evaluate the expression of tryptophan hydroxylase (TpH-1) in gastric mucosa of patients with symptomatic and asymptomatic H. pylori infection in relation to the intensity of bacterial colonization and severity of dyspeptic symptoms.

MATERIAL AND METHODS

Ninety subjects (aged 35-49 years) were enrolled in the study and separated into 3 groups of 30 subjects each. Group I - healthy volunteers without H. pylori infection, group II - subjects with asymptomatic H. pylori infection, group III - H. pylori-infected patients with dyspeptic symptoms, mainly fasting and nocturnal epigastric pain. To diagnose H. pylori infection the urea breath test (UBT-13C) and histological analysis were performed. The level of mRNA expression of tryptophan hydroxylase (TpH-1) was estimated in gastric mucosa with RT-PCR.

RESULTS

The expression of this enzyme in antral mucosa was 2.69 ±0.97 in group I, 2.28 ±0.69 in group II (p > 0.05) and 4.40 ±1.64 in group III (p < 0.001). The levels of expression of TpH-1 in gastric body mucosa were 2.16 ±0.70, 1.57 ±0.52 (p > 0.05) and 3.40 ±1.51 (p < 0.001), respectively. In group III a positive correlation was found between intensity of H. pylori colonization and TpH-1 expression as well as between TpH-1 expression and severity of dyspeptic symptoms.

CONCLUSIONS

Increased expression of TpH-1 in gastric mucosa plays a role in pathogenesis of chronic dyspepsia.

Helicobacter pylori infection in children: an overview of diagnostic methods

Children differ from adults regarding Helicobacter pylori (H. pylori) infection in many terms. H. pylori infection represents a key factor in the pathogenesis of duodenal ulcer and chronic gastritis in children. H. pylori infection causes some extraintestinal diseases as well as gastrointestinal diseases. Although, among these illnesses in children, symptoms like recurrent abdominal pain are not specific. Moreover, the role of the pathogen in the growth faltering, iron deficiency anemia, and asthma still remains controversial. A reliable method to detect H. pylori infection is a crucial issue, sand is still a matter of active debate. The tests applied for H. pylori diagnosis are grouped as either invasive or non-invasive methods. Invasive methods consist of endoscopic evaluation, the rapid urease test (RUT), histology, and bacterial culture. Non-invasive tests include the urea breath test (UBT), stool antigen test (SAT), serology, and molecular diagnostic approaches. Use of endoscopy is a pre-requisite for all invasive methods and poses difficulties in children as it is a difficult procedure and requires patient's cooperation. For this reason, the non-invasive tests have been commonly used in children, although their accuracy is not very reliable in some cases. Invasive tests may be opted to confirm the diagnosis as and when needed. This review presents the diagnostic tests used to detect H. pylori infection in children.

Evaluation of Helicobacter pylori Infection and Clarithromycin Resistance in Strains From Symptomatic Colombian Children

The aim of the study was to determine the current prevalence of Helicobacter pylori in symptomatic Colombian children and evaluate the presence of mutations associated with clarithromycin resistance. Biopsies from 133 children were analyzed. The gastric fragment was used for urease test and reused for polymerase chain reaction sequencing of the 23SrDNA gene. Mutations were detected by bioinformatic analysis. Polymerase chain reaction sequencing established that H pylori infection was present in 47% of patients. Bioinformatics analysis of the 62 positive sequences for 23SrDNA revealed that 92% exhibited a genotype susceptible to clarithromycin, whereas the remaining strains (8%) showed mutations associated with clarithromycin resistance. The low rate of resistance to clarithromycin (8%) suggests that conventional treatment methods are an appropriate choice for children. Recycling a biopsy that is normally discarded reduces the risks associated with the procedure. The 23SrDNA gene amplification could be used for a dual purpose: detection of H pylori and determination of susceptibility to clarithromycin.

Detection of Helicobacter pylori in stool samples of young children using real-time polymerase chain reaction

BACKGROUND

The aims of this study were to develop and validate a multiplex real-time polymerase chain reaction (q-PCR) assay of Helicobacter pylori in stool samples of healthy children. Additionally, we determined the prevalence of clarithromycin resistance and cagA gene in H. pylori-positive samples.

MATERIALS AND METHODS

Archived stool samples from 188 children aged 6-9 years and 272 samples of 92 infants aged 2-18 months were tested for H. pylori antigens using enzyme immunoassay (EIA). A multiplex q-PCR assay was designed to detect H. pylori 16S rRNA and urease and the human RNase P gene as an internal control. Kappa coefficient was calculated to assess the agreement between q-PCR and EIA.

RESULTS

Laboratory validation of the q-PCR assay using quantitated H. pylori ATCC 43504 extracted DNA showed S-shaped amplification curves for all genes; the limit of detection was 1 CFU/reaction. No cross-reactivity with other bacterial pathogens was noted. Applying the multiplex q-PCR to DNA extracted from fecal samples showed clear amplification curves for urease gene, but not for 16S rRNA. The prevalence of H. pylori infection was 50% (95% CI 43%-57%) by q-PCR (urease cycle threshold <44) vs 59% (95% CI 52%-66%) by EIA. Kappa coefficient was .80 (P < .001) and .44 (P < .001) for children aged 6-9 years and 2-18 months, respectively. Sixteen samples were positive for cagA and three were positive for clarithromycin resistance mutation (A2143G) as confirmed by sequencing.

CONCLUSIONS

The developed q-PCR can be used as a cotechnique to enhance the accuracy of H. pylori detection in epidemiological studies and in clinical settings.

Review: Prevalence and dynamics of Helicobacter pylori infection during childhood

INTRODUCTION

Long-term persistent Helicobacter pylori infection has been associated with ulceropeptic disease and gastric cancer. Although H. pylori is predominantly acquired early in life, a clear understanding of infection dynamics during childhood has been obfuscated by the diversity of populations evaluated, study designs, and methods used.

AIM

Update understanding of true prevalence of H. pylori infection during childhood, based on a critical analysis of the literature published in the past 5 years.

METHODS

Comprehensive review and meta-analysis of original studies published from 2011 to 2016.

RESULTS

A MEDLINE^® /PubMed^® search on May 1, 2016, using the terms pylori and children, and subsequent exclusion, based on abstract review using predefined criteria, resulted in 261 citations. An Embase^® search with the same criteria added an additional 8 citations. In healthy children, meta-analysis estimated an overall seroprevalence rate of 33% (95% CI: 27%-38%). Seven healthy cohort studies using noninvasive direct detection methods showed infection prevalence estimates ranging from 20% to 50% in children ≤5 and 38% to 79% in children >5 years. The probability of infection persistence after a first positive sample ranged from 49% to 95%. Model estimates of cross-sectional direct detection studies in asymptomatic children indicated a prevalence of 37% (95% CI: 30%-44%). Seroprevalence, but not direct detection rates increased with age; both decreased with increasing income. The model estimate based on cross-sectional studies in symptomatic children was 39% (95% CI: 35%-43%).

CONCLUSIONS

The prevalence of H. pylori infection varied widely in the studies included here; nevertheless, model estimates by detection type were similar, suggesting that overall, one-third of children worldwide are or have been infected. The few cohort and longitudinal studies available show variability, but most studies, show infection rates over 30%. Rather surprisingly, overall infection prevalence in symptomatic children was only slightly higher, around 40%. Studies including only one positive stool sample should be interpreted with caution as spontaneous clearance can occur.

Role of Helicobacter pylori Infection in Body Height of Adult Dyspeptic Patients

INTRODUCTION

The prevalence of H. pylori infection is high in underdeveloped countries and is associated with growth retardation. In the first half of the 20th century, Sardinia was an underdeveloped region; however, more recent development resulted in a decline in H. pylori infection. Because body height is correlated with health and nutritional status in childhood, the association among H. pylori infection and height was explored.

MATERIALS AND METHODS

A retrospective observational study was conducted involving patients undergoing endoscopy for dyspepsia from 2002 to 2012. H. pylori status was assessed by histology plus the rapid urease test or 13Carbon-urea breath test.

RESULTS

Body height and H. pylori status were assessed in 5045 adult patients: 3257 (64.6%) were women. Patients born after 1950 showed a significant increase in height (average 3.22 cm) compared to patients born before 1950 (163.93 vs 160 cm; 95% confidence interval, CI = 2.74-3.70 cm) (p < .0001). H. pylori-infected patients were nearly 1 cm shorter than uninfected patients (95% CI = -1.35 to·-0.09 cm) (p = .012). The multivariate linear regression analysis showed male gender, birth cohort, and occupational categories to be strongly associated with height, while the weak effect of H. pylori infection disappeared.

CONCLUSIONS

Our results demonstrate a strong secular trend related to body height in Sardinia with a minimal influence of H. pylori infection.

Diagnosis of Helicobacter pylori infection: Current options and developments

Accurate diagnosis of Helicobacter pylori (H. pylori) infection is a crucial part in the effective management of many gastroduodenal diseases. Several invasive and non-invasive diagnostic tests are available for the detection of H. pylori and each test has its usefulness and limitations in different clinical situations. Although none can be considered as a single gold standard in clinical practice, several techniques have been developed to give the more reliable results. Invasive tests are performed via endoscopic biopsy specimens and these tests include histology, culture, rapid urease test as well as molecular methods. Developments of endoscopic equipment also contribute to the real-time diagnosis of H. pylori during endoscopy. Urea breathing test and stool antigen test are most widely used non-invasive tests, whereas serology is useful in screening and epidemiological studies. Molecular methods have been used in variable specimens other than gastric mucosa. More than detection of H. pylori infection, several tests are introduced into the evaluation of virulence factors and antibiotic sensitivity of H. pylori, as well as screening precancerous lesions and gastric cancer. The aim of this article is to review the current options and novel developments of diagnostic tests and their applications in different clinical conditions or for specific purposes.

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.

Helicobacter pylori hopQ alleles (type I and II) in gastric cancer

The Helicobacter pylori (H. pylori) outer membrane protein (HopQ) of is one of the proteins involved in bacterial adherence to gastric mucosa and has been suggested to have a role in the virulence of H. pylori. The aim of the present study was to determine the association between H. pylori virulence types I and II hopQ genotypes and patients with different gastrointestinal diseases. A polymerase chain reaction-based assay was used to determine the presence of type I and type II hopQ genes in 88 H. pylori strains isolated from H. pylori-infected patients. Of the total 88 H. pylori isolates, type I and type II hopQ alleles were detected in 52 (59.1%) and 36 (40.9%), respectively. A significant association was found between type I hopQ gene and gastric cancer [odds ratio, 2.3; 95% confidence interval (CI), 1.3-4.1] and gastric ulcers (odds ratio, 2.5; 95% CI, 1.4-4.3). A significant association was also identified between the type II hopQ gene and gastric cancer (odds ratio, 2.4; 95% CI, 1.1-3.0). The association between hopQ type I and hopQ type II genotypes and clinical status suggest that these genes may be helpful in the universal prediction of specific disease risks.

Diagnosis of Helicobacter pylori infection: Current options and developments

Accurate diagnosis of Helicobacter pylori (H. pylori) infection is a crucial part in the effective management of many gastroduodenal diseases. Several invasive and non-invasive diagnostic tests are available for the detection of H. pylori and each test has its usefulness and limitations in different clinical situations. Although none can be considered as a single gold standard in clinical practice, several techniques have been developed to give the more reliable results. Invasive tests are performed via endoscopic biopsy specimens and these tests include histology, culture, rapid urease test as well as molecular methods. Developments of endoscopic equipment also contribute to the real-time diagnosis of H. pylori during endoscopy. Urea breathing test and stool antigen test are most widely used non-invasive tests, whereas serology is useful in screening and epidemiological studies. Molecular methods have been used in variable specimens other than gastric mucosa. More than detection of H. pylori infection, several tests are introduced into the evaluation of virulence factors and antibiotic sensitivity of H. pylori, as well as screening precancerous lesions and gastric cancer. The aim of this article is to review the current options and novel developments of diagnostic tests and their applications in different clinical conditions or for specific purposes.

What exists beyond cagA and vacA? Helicobacter pylori genes in gastric diseases

Helicobacter pylori (H. pylori) infection is present in more than half the world's population and has been associated with several gastric disorders, such as gastritis, peptic ulceration, and gastric adenocarcinoma. The clinical outcome of this infection depends on host and bacterial factors where H. pylori virulence genes seem to play a relevant role. Studies of cagA and vacA genes established that they were determining factors in gastric pathogenesis. However, there are gastric cancer cases that are cagA-negative. Several other virulence genes have been searched for, but these genes remain less well known that cagA and vacA. Thus, this review aimed to establish which genes have been suggested as potentially relevant virulence factors for H. pylori-associated gastrointestinal diseases. We focused on the cag-pathogenicity island, genes with adherence and motility functions, and iceA based on the relevance shown in several studies in the literature.

Microevolution of Virulence-Related Genes in Helicobacter pylori Familial Infection

Helicobacter pylori, a bacterial pathogen that can infect human stomach causing gastritis, ulcers and cancer, is known to have a high degree of genome/epigenome diversity as the result of mutation and recombination. The bacteria often infect in childhood and persist for the life of the host. One of the reasons of the rapid evolution of H. pylori is that it changes its genome drastically for adaptation to a new host. To investigate microevolution and adaptation of the H. pylori genome, we undertook whole genome sequencing of the same or very similar sequence type in multi-locus sequence typing (MLST) with seven genes in members of the same family consisting of parents and children in Japan. Detection of nucleotide substitutions revealed likely transmission pathways involving children. Nonsynonymous (amino acid changing) mutations were found in virulence-related genes (cag genes, vacA, hcpDX, tnfα, ggt, htrA and the collagenase gene), outer membrane protein (OMP) genes and other cell surface-related protein genes, signal transduction genes and restriction-modification genes. We reconstructed various pathways by which H. pylori can adapt to a new human host, and our results raised the possibility that the mutational changes in virulence-related genes have a role in adaptation to a child host. Changes in restriction-modification genes might remodel the methylome and transcriptome to help adaptation. This study has provided insights into H. pylori transmission and virulence and has implications for basic research as well as clinical practice.

Persistent and transient Helicobacter pylori infections in early childhood

BACKGROUND

Helicobacter pylori, the main cause of peptic ulcer disease and gastric cancer in adult populations, is generally acquired during the first years of life. Infection can be persistent or transient and bacterial and host factors determining persistence are largely unknown and may prove relevant for future disease.

METHODS

Two cohorts of healthy Chilean infants (313 total) were evaluated every 3 months for 18-57 months to determine pathogen- and host-factors associated with persistent and transient infection.

RESULTS

One-third had at least one positive stool ELISA by age 3, with 20% overall persistence. Persistent infections were acquired at an earlier age, associated with more household members, decreased duration of breastfeeding, and nonsecretor status compared to transient infections. The cagA positive strains were more common in persistent stools, and nearly 60% of fully characterized persistent stool samples amplified cagA/vacAs1m1. Persistent children were more likely to elicit a serologic immune response, and both infection groups had differential gene expression profiles, including genes associated with cancer suppression when compared to healthy controls.

CONCLUSIONS

These results indicate that persistent H. pylori infections acquired early in life are associated with specific host and/or strain profiles possibly associated with future disease occurrence.

CagA phosphorylation EPIYA-C motifs and the vacA i genotype in Helicobacter pylori strains of asymptomatic children from a high-risk gastric cancer area in northeastern Brazil

Helicobacter pylori infection is one of the most common infections worldwide and is associated with gastric diseases. Virulence factors such as VacA and CagA have been shown to increase the risk of these diseases. Studies have suggested a causal role of CagA EPIYA-C in gastric carcinogenesis and this factor has been shown to be geographically diverse. We investigated the number of CagA EPIYA motifs and the vacA i genotypes in H. pylori strains from asymptomatic children. We included samples from 40 infected children (18 females and 22 males), extracted DNA directly from the gastric mucus/juice (obtained using the string procedure) and analysed the DNA using polymerase chain reaction and DNA sequencing. The vacA i1 genotype was present in 30 (75%) samples, the i2 allele was present in nine (22.5%) samples and both alleles were present in one (2.5%) sample. The cagA-positive samples showed distinct patterns in the 3&#8217; variable region of cagA and 18 of the 30 (60%) strains contained 1 EPIYA-C motif, whereas 12 (40%) strains contained two EPIYA-C motifs. We confirmed that the studied population was colonised early by the most virulent H. pylori strains, as demonstrated by the high frequency of the vacA i1 allele and the high number of EPIYA-C motifs. Therefore, asymptomatic children from an urban community in Fortaleza in northeastern Brazil are frequently colonised with the most virulent H. pylori strains.

Evaluation of Helicobacter pylori vacA and cagA Genotypes and Correlation With Clinical Outcome in Patients With Dyspepsia in Hamadan Province, Iran

Background:

Helicobacter pylori is known to be a causative agent of chronic active gastritis, peptic ulcer and gastric cancer in human. Diverse genotypes of H. pylori strains have different virulence potency and geographic distribution.

Objectives:

The purpose of this study was to investigate the association between the cytotoxin-associated gene (cagA), and the various vacuolating cytotoxin (vacA) genotypes of H. pylori strains and clinical outcomes in patients referred to Shahid-Beheshti Hospital in Hamadan, Iran.

Patients and Methods:

In this cross-sectional study, biopsy samples were collected consecutively from 153 patients with gastric cancer (GC), peptic ulcer dyspepsia (PUD) and non-ulcer dyspepsia (NUD) in the gastroenterology department of Shahid-Beheshti Hospital in Hamadan province, the west of Iran. H. pylori infection was confirmed in 83 patients (3 with GC, 27 with PUD, and 53 with NUD) by histology, rapid urease test (RUT) and culture. Genomic DNA was extracted from the bacterial isolate and was further confirmed with 16S rRNA gene sequencing as H. pylori, and characterized based on cagA and vacA genotyping using the polymerase chain reaction (PCR) method.

Results:

In this study, vacA genotypes s1/m2, s1/m1, s2/m2 and s2/m1 were determined in 43.4%, 19.3%, 13.2% and 6% of the isolated H. pylori, respectively. The vacAs1 genotype was detected in 52 (62.6%) isolates, of which the vacAs1a genotype was detected in 45.2, 40.7, and 66.6% of the isolates from patients with NUD, PUD, and GC, respectively. The cagA-positive genotype was determined in 73 (87.9%) isolates and 10 (12.1%) were negative. The frequency rates of cagA gene were 84.9, 92.6 and 100% in isolates of patients with NUD, PUD, and GC, respectively. The cagA-positive genotype is strongly associated with s1a/m2 and s1a/m1 vacA genotypes.

Conclusions:

The most predominant VacA genotypes in our areas were s1/m2 and s1/m1, which regard as the genotypes with more virulence intensity. The H. pylorivacAs1a, cagA genotypes have a significant relationship with the presence of PUD and GC in Iranian patients with dyspepsia.

High Prevalence of Helicobacter pylori hopQ II Genotype Isolated from Iranian Patients with Gastroduodenal Disorders

Helicobacter pylori plays an important role in the pathogenesis of chronic gastritis, peptic ulceration, and noncardia gastric cancer. Several putative virulence factors for H. pylori have been identified including vacA, babA, and iceA. HopQ is one of the outer membrane proteins involved in bacterial adherence to gastric mucosa and has been suggested to also play a role in the virulence of H. pylori. Due to the substantial geographic differences in the prevalence of H. pylori virulence factors reported, the main purpose of the current study was to investigate the association between different H. pylori virulence hopQ alleles (types I and II) and patients with gastroduodenal disorders. The presence of H. pylori and hopQ alleles in gastric biopsy specimens was identified by specific PCR assays. H. pylori type II hopQ was found to be significantly associated with gastric cancer patients (odds ratio: 3.47, 95% CI: 1.56–5.89). Information about the prevalence of H. pylori hopQ type II can be used for determining the high-risk diseases type which is actually colonized by H. pylori hopQ type II positive strains. The presence of H. pylori hopQ type II should be investigated in different geographical regions as confirmatory findings may provide a definite biomarker attributed to the pathogenesis of certain severe digestive diseases.

Human and Helicobacter pylori coevolution shapes the risk of gastric disease

Helicobacter pylori is the principal cause of gastric cancer, the second leading cause of cancer mortality worldwide. However, H. pylori prevalence generally does not predict cancer incidence. To determine whether coevolution between host and pathogen influences disease risk, we examined the association between the severity of gastric lesions and patterns of genomic variation in matched human and H. pylori samples. Patients were recruited from two geographically distinct Colombian populations with significantly different incidences of gastric cancer, but virtually identical prevalence of H. pylori infection. All H. pylori isolates contained the genetic signatures of multiple ancestries, with an ancestral African cluster predominating in a low-risk, coastal population and a European cluster in a high-risk, mountain population. The human ancestry of the biopsied individuals also varied with geography, with mostly African ancestry in the coastal region (58%), and mostly Amerindian ancestry in the mountain region (67%). The interaction between the host and pathogen ancestries completely accounted for the difference in the severity of gastric lesions in the two regions of Colombia. In particular, African H. pylori ancestry was relatively benign in humans of African ancestry but was deleterious in individuals with substantial Amerindian ancestry. Thus, coevolution likely modulated disease risk, and the disruption of coevolved human and H. pylori genomes can explain the high incidence of gastric disease in the mountain population.

Helicobacter pylori in pediatrics

This review concerned the important pediatric studies published between April 2012 and March 2013. Symptomatology in Helicobacter pylori-positive children is nonspecific, except for those suffering from peptic ulcer diseases. Investigation of H. pylori status in children and adolescents with sideropenic anemia is recommended, and it is the aim of several studies worldwide. Associations of H. pylori with plasma ghrelin levels as well as the negative association of H. pylori with atopic disease were interesting objectives for several studies this year. Success rates of sequential therapy tended to be lower in recent studies than in previous trials, which probably reflects the increase in macrolide resistance. A beneficial effect of probiotics was reported although not all trials supported this result in children. Intrafamilial transmission and young age could be major risk factors associated with reinfection in children.

Helicobacter pylori in pediatrics

This review summarizes important pediatric studies published from April 2011 up to March 2012. Proteomics profile of ulcerogenic Helicobacter pylori strains was defined in the most interesting study of the last year. The antigen stool test is becoming the "gold standard" in prevalence studies, and according to the last epidemiologic studies, the prevalence of H. pylori infection in childhood is not decreasing any more in the developed world. The resistance rate of H. pylori strains is high in children. Therefore, among other important issues concerning H. pylori in pediatrics, guidelines published by ESPGHAN and NASPGHAN last year also recommended culture and susceptibility testing before first-line treatment in areas with high or unknown antibiotic resistance rates.

Epidemiology and diagnosis of Helicobacter pylori infection

Medline, PubMed and the Cochrane databases were searched on epidemiology and diagnosis of Helicobacter pylori for the period of April 2011-March 2012. Several studies have shown that the prevalence of H. pylori infection is decreasing in adults and children in many countries. Various diagnostic tests are available, and most of them have high sensitivity and specificity. The Maastricht IV/Florence consensus report states that the urea breath test using (13)C urea remains the best test to diagnose H. pylori infection. Among the stool antigen tests, the ELISA monoclonal antibody test is recommended. All these tests were used, either as a single diagnostic test or in combination, to investigate H. pylori infection among different populations throughout the world. Of particular interest, current improvements in high-resolution endoscopic technologies enable increased diagnostic accuracy for the detection of H. pylori infection, but none of these techniques, at present, are specific enough for obtaining a real-time diagnosis of H. pylori infection.