Analysis of Helicobacter pylori genotypes and correlation with clinical outcome in Turkey

Accuracy of Fecal Polymerase Chain Reaction Testing in Clarithromycin-Resistant Helicobacter Pylori: A Systematic Review and Meta-Analysis

INTRODUCTION

The increasing prevalence of clarithromycin (CLA)-resistant Helicobacter pylori(H. pylori) strains poses a significant challenge in the management of H. pylori infections. This systematic review and meta-analysis investigates the diagnostic accuracy of polymerase chain reaction (PCR) in identifying CLA-resistant H. pylori strains in stool.

METHODS

A comprehensive literature search was conducted using PubMed, Embase, and Cochrane databases from database inception to April 30, 2023. Eligible studies evaluated the effectiveness of PCR stool tests in detecting CLA-resistant H. pylori strains in adults (>18-year-old). Studies of pediatric populations, alternative methods to PCR or stool samples, and reference tests other than gastric biopsy were excluded. The bivariate random-effects model was used to pool diagnostic accuracy from the included studies.

RESULTS

The analysis of 11 prospective diagnostic studies with a total of 866 patients showed a pooled sensitivity of 0.97 (95% CI: 0.9-0.99) and a pooled specificity of 0.98 (95% CI: 0.81-1.00). Subgroup analysis based on the used technique demonstrated consistent findings without notable variations. The diagnostic odds ratio was calculated at 1843.92 (95% CI: 134.28-25,321.3). The positive likelihood ratio was determined as 51.02 (95% CI: 4.61-564.5), while the negative likelihood ratio was found to be 0.03 (95% CI: 0.01-0.1).

DISCUSSION

PCR testing for clarithromycin-resistant H. pylori was highly sensitive and specific across studies with proven reliability in clinical practice, particularly in outpatient settings. Their implementation offers cost-effectiveness and the potential for tailored treatment strategies, holding promise for improved patient outcomes.

Virulence gene polymorphisms in Shandong Helicobacter pylori strains and their relevance to gastric cancer

BACKGROUND

Helicobacter pylori (H. pylori) virulence factors, particularly the cagA and vacA genotypes, play important roles in the pathogenic process of gastrointestinal disease.

METHODS

The cagA and vacA genotypes of 87 H. pylori strains were determined by PCR and sequencing. The EPIYA and CM motif patterns were analyzed and related to clinical outcomes. We examined the associations between the virulence genes of H. pylori and gastrointestinal diseases in Shandong, and the results were analyzed via the chi-square test and logistic regression model.

RESULTS

Overall, 76 (87.36%) of the strains carried the East Asian-type CagA, with the ABD types being the most prevalent (90.79%). However, no significant differences were observed among the different clinical outcomes. The analysis of CagA sequence types revealed 8 distinct types, encompassing 250 EPIYA motifs, including 4 types of EPIYA or EPIYA-like sequences. Additionally, 28 CM motifs were identified, with the most prevalent patterns being E (66.67%), D (16.09%), and W-W (5.75%). Notably, a significant association was discovered between strains with GC and the CM motif pattern D (P < 0.01). With respect to the vacA genotypes, the strains were identified as s1, s2, m1, m2, i1, i2, d1, d2, c1, and c2 in 87 (100%), 0 (0), 26 (29.89%), 61 (70.11%), 73 (83.91%), 14 (16.09%), 76 (87.36%), 11 (12.64%), 18 (20.69%), and 69 (79.31%), respectively. Specifically, the vacA m1 and c1 genotypes presented a significantly greater prevalence in strains from GC compared to CG (P < 0.05). Following adjustment for age and sex, the vacA c1 genotype demonstrated a notable association with GC (OR = 5.174; 95% CI, 1.402-20.810; P = 0.012). This association was both independent of and more pronounced than the correlations between vacA m1 and GC.

CONCLUSIONS

CagA proteins possessing CM motif pattern D were more frequently observed in patients with GC (P < 0.01), implying a potentially higher virulence of CM motif pattern D than the other CM motif patterns. Moreover, a strong positive association was identified between the vacA c1 genotype and GC, indicating that the vacA c1 genotype is a robust risk indicator for GC among male patients aged ≥55 years in Shandong.

A Genetic and Immunohistochemical Analysis of Helicobacter pylori Phenotypes and p27 Expression in Adenocarcinoma Patients in Jordan

Stomach (gastric) cancer is one of the most prevalent and deadly cancers worldwide and most gastric cancers are adenocarcinomas. Based on prior research, there is an association between Helicobacter pylori (H. pylori) infection together with the frequency of duodenal ulcer, distal gastric adenocarcinoma, mucosa-associated lymphoid tissue (MALT) lymphoma, and antral gastritis. Helicobacter pylori virulence and toxicity factors have been identified before that significantly influence the clinical outcomes of H. pylori infection and gastric adenocarcinoma. However, it remains unclear exactly how different strains of H. pylori affect gastric adenocarcinoma. Current research suggests this involves tumor suppressor genes, like p27 but also H. pylori toxic virulence proteins. Therefore, we quantified known H. pylori genotypes within adenocarcinoma patients to establish the prevalence of known toxins that include cytotoxin-associated gene A (cagA) as well as vacuolating cytotoxin A (vacA) within patients of variable adenocarcinoma diagnosis. This analysis used gastrectomy samples validated for DNA viability. The incidence of H. pylori in adenocarcinoma patients in Jordan was established to be 54.5% positive (ureA gene positive) with cagA genotype occurrence at 57.1%, but also in this population study vacA gene ratios found to be 24.7%:22.1%:14.3%:14.3%. (vacAs1:vacAs2:vacAm1:vacAm2). Using immunohistochemistry (IHC), we confirmed with statistical significance that p27 was dysregulated and suppressed, within nearly all H. pylori vacA genotypes. In addition, within 24.6% of H. pylori samples analyzed was a different bacterial genotype, and curiously that p27 protein expression was retained in 12% of tested adenocarcinoma H. pylori samples. This is suggestive that p27 could be used as a prognostic indicator but also that an unknown genotype could be contributing to the regulatory effects of p27 protein within this bacterial and cellular environment that may include other virulence factors and unknown immune system regulatory changes.

Glycopeptidomics Analysis of a Cell Line Model Revealing Pathogenesis and Potential Marker Molecules for the Early Diagnosis of Gastric MALT Lymphoma

Background & Aims

Gastric mucosa-associated lymphoma (GML) is a mature B cell tumor related to Helicobacter pylori (H.pylori) infection. The clinical manifestations of GML are not specific, so GML is often misdiagnosed, leading to excessive treatment. The pathogenesis of H.pylori-induced GML is not well understood and there are no molecular markers for early GML diagnosis.

Methods

Glycopeptidomics analyses of host cell lines (a BCG823 cell line, C823) and C823 cells infected by H. pylori isolated from patients with GML (GMALT823), gastritis (GAT823), gastric ulcer (GAU823) and gastric cancer (GAC823) were carried out to clarify the host reaction mechanism against GML and to identify potential molecular criteria for the early diagnosis of GML.

Results

Thirty-three samples were analyzed and approximately 2000 proteins, 200 glycoproteins and 500 glycopeptides were detected in each sample. O-glycans were the dominant glycoforms in GMALT823 cells only. Four specific glycoforms in GMALT823 cells and 2 specific glycoforms in C823 and GMALT823 cells were identified. Eight specific glycopeptides from 7 glycoproteins were found in GMALT823 cells; of these glycopeptides, 6 and 3 specific glycopeptides had high affinity for T cell epitopes and have conformational B cell epitopes, respectively.

Conclusion

The predominant glycoforms of host cells infected by MALT H. pylori isolates differ from others, and the glycoproteins, glycosylation sites and glycoforms might be closely related to the formation of GML, which provides new insights into the pathogenic mechanisms of H. pylori infection and suggests molecular indicators for the early diagnosis of GML.

Helicobacter pylori-related risk predictors of gastric cancer: The latest models, challenges, and future prospects

Helicobacter pylori is known as an important determinant of preneoplastic lesions or gastric cancer (GC) risk. The bacterial genotypes may determine the clinical outcomes. However, the evidence for these associations has varied between and within continents, and the actual effect of each gene and corresponding allelic variants are still debatable. In recent years, two new models have been proposed to predict the risk of GC; the phylogeographic origin of H. pylori strains and a disrupted co-evolution between H. pylori and its human host, which potentially explain the geographic differences in the risk of H. pylori-related cancer. However, these models and earlier ones based on putative virulence factors of the bacterium may not fully justify differences in the incidence of GC, reflecting that new theories should be developed and examined. Notably, the new findings also support the role of ancestry-specific germline alteration in contributing to the ethnic/population differences in cancer risk. Moreover the high and low incidence areas of GC have shown differences in transmission ecology, largely affecting the composition of H. pylori populations. As a new hypothesis, it is proposed that any high-risk population may have its own specific risk loci (or variants) as well as new H. pylori strains with national/maybe regional gene pools that should be considered. The latter is seen in the Americas where the rapid evolution of distinct H. pylori subpopulations has been occurred. It is therefore proposed that the deep sequencing of both H. pylori and its human host is simultaneously performed in GC patients and age-sex-matched controls from high-risk areas. The expression and functional activities of the identified new determinants of GC must then be assessed and matched with human and pathogen ancestry, because some of risk loci are ancestry-specific. In addition, potential study-level covariates and moderator variables (eg physical conditions, life styles, gastric microbiome, etc) linked to causal relationships, and their impact, should be recognized and controlled.

Detection of Anti-CagA Antibodies in Sera of Helicobacter pylori-Infected Patients Using an Immunochromatographic Test Strip

The cagA gene of Helicobacter pylori that encodes an immunodominant CagA protein provokes severe mucosal damage and acts as a risk factor for the development of peptic ulcer disease and gastric cancer. Our aim is to develop an immunochromatographic test strip (ICTS) using our previously developed recombinant CagA (rCagA) protein and anti-rCagA monoclonal antibody (Mab) for the detection of anti-CagA antibodies in sera of infected patients. The rCagA was firstly conjugated to gold nanoparticle and placed into the conjugate pad. A nonconjugated rCagA and anti-rCagA Mab (CK-02) were immobilized on the test line and control line, respectively. Biopsy and serum samples from 30 H. pylori-infected patients were used. The presence of cagA gene in biopsy samples was first detected by PCR (Polymerase Chain Reaction), and 22 patients were found positive while 8 were negative. When serum samples were tested by our developed ICTS, 21 were positive for anti-CagA antibodies while 9 were negative. The serum samples were also tested by a commercial ELISA (Enzyme Linked Immunosorbent Assay), and when compared to the ICTS a sensitivity of 95% and a specificity of 100% were obtained. The ICTS can be used for rapid detection of CagA-positive H. pylori infection instead of expensive, time consuming and laborious invasive approaches.

Helicobacter pylori Infection, Virulence Genes' Distribution and Accompanying Clinical Outcomes: The West Africa Situation

Data on Helicobacter pylori (H. pylori) infection and virulence factors in countries across West Africa are scattered. This systematic review seeks to present an update on the status of H. pylori infection focusing on prevalence rate, distribution of virulent genes, and their link to clinical outcomes across countries in the western part of Africa. This information is expected to broaden the knowledge base of clinicians and researchers regarding H. pylori infection and associated virulence factors in West African countries. Search Method. A comprehensive search of the scientific literature in PubMed and ScienceDirect was conducted using the search terms including “Helicobacter pylori infection in West Africa”. Databases were sourced from January 1988 to December 2018. Results. Data on the incidence of H. pylori infection and related pathological factors were found for some countries, whereas others had no information on it. Smoking, alcohol, exposure to high levels of carcinogens and diet were reported to be involved in the pathogenesis of gastroduodenal diseases and gastric cancer. Besides the environmental factors and genetic characteristics, there are important characteristics of H. pylori such as the ability to infect, replicate, and persist in a host that have been associated with the pathogenesis of various gastroduodenal diseases. Concluding Remarks. This systematic search has provided information so far available on H. pylori virulence factors and clinical outcomes in West Africa. Accordingly, this piece has identified gaps in the body of knowledge highlighting the need for more studies to clarify the role of H. pylori virulence factors and associated clinical outcomes in the burden of this bacterial infection in West Africa, as data from these countries do not give the needed direct relation.

Prevalence of Helicobacter pylori in Turkish children with celiac disease and its effect on clinical, histopathological, and laboratory parameters

INTRODUCTION

The aim of the study was to assess the prevalence of Helicobacter pylori (HP) in children with celiac disease (CD) and its relationship with clinical, histopathological, and laboratory parameters.

MATERIAL AND METHODS

Two hundred and fifty-six patients with serologically and histopathologically diagnosed CD at the Pediatric Gastroenterology Department, Turkey, from January 2012 to March 2017, were included in the study, as well as 1012 patients with dyspeptic complaints. Biopsies of the duodenum and antrum were taken; the existence of HP and the histological level of damage were studied. HP (+) and HP (-) cases were compared according to age, sex, noted complaints, and clinical and laboratory features.

RESULTS

Seventy (27.4%) CD patients and 270 (26.7%) patients with dyspeptic complaints were HP (+). The diagnostic age was higher in HP (+) cases, and diarrhea and abdominal distension were significantly higher. Although hemoglobin, ferritin, vitamin B12, and transferrin saturation were lower in HP (+) cases, the differences were not statistically significant. The serum folate level in the HP (+) group was significantly lower compared to the HP (-) group.

CONCLUSIONS

The prevalence of HP was not increased in cases of CD. The CD was diagnosed later in HP (+) cases, distension and diarrhea complaints were more frequent, and folate deficiency was significant.

Concurrent detection of cagA, vacA, sodB and hsp60 virulence genes and their relationship with clinical outcomes of disease in Helicobacter pylori isolated strains of southwest of Iran

BACKGROUND AND OBJECTIVES

Helicobacter pylori is a Gram-negative spiral-shaped bacterium that contaminates more than half of the world's inhabitants, and infection with this bacterium is associated with some gastric disorders. Also, 5% to 10% of H. pylori genes are specific to this bacterium and many bacterial virulence factors fall into this group. The cagA, vacA, sodB and hsp60 are among important virulence factors of H. pylori.

MATERIALS AND METHODS

A gastric biopsy specimen was taken from 341 gastric patients and cultivated on a Colombia agar plate, containing various antibiotics, such as vancomycin, amphotericin B, and trimethoprim & polymyxin B, and incubated for 3 to 10 days under microaerophilic conditions at 37°C. PCR was used to detect the ureC, cagA, vacA, sodB and hsp60 genes.

RESULTS

In this study, 131 isolates were identified as H. pylori. The prevalence of cagA, vacA, sodB and hsp60 were 74%, 100%, 92.4% and 96.2%, respectively. The correlation between the clinical forms of the disease and the virulence genes were analyzed by statistical tests and no significant correlation was found.

CONCLUSION

The obtained results are similar to some studies conducted in different parts of the world and is different in other cases. This discrepancy is due to the difference in the type of gastric disorders, sample size and methodology.

Interactions between Helicobacter pylori and gastroesophageal reflux disease

Interactions between Helicobacter Pylori (HP) and gastroesophageal reflux disease (GERD) are a complex issue. Several pathophysiological factors influence the development and the course of GERD, HP infection might be only one of these. Many studies emphasize the co-existence of these diseases. HP infection could contribute to GERD through both a protective and an aggressive role. Gastric acid secretion is a key factor in the pathophysiology of reflux esophagitis. Depending on the type of gastritis related to HP, acid secretion may either increase or decrease. Gastritis in corpus leads to hypoacidity, while antrum gastritis leads to hyperacidity. In cases of antral gastritis and duodenal ulcers which have hyperacidity, the expectation is an improvement in pre-existing reflux esophagitis after eradication of HP. In adults, HP infection is often associated with atrophic gastritis in the corpus. Atrophic gastritis may protect against GERD. Pangastritis which leads to gastric atrophy is commonly associated with CagA strains of HP and it causes more severe gastric inflammation. In case of HP-positive corpus gastritis in the stomach, pangastritis, and atrophic gastritis, reflux esophagitis occurs frequently after eradication of HP. Nonetheless, as a predisposing disease of gastric cancer, HP should be treated. In conclusion, as the determinative factors affecting GERD involving in HP, detailed data on the location of gastric inflammation and CagA positivity should be obtained by the studies at future.

Genotyping and antibiotic resistance properties of Helicobacter pylori strains isolated from human and animal gastric biopsies

Purpose

The present study was done to assess the prevalence rate, antibiotic resistance pattern and genotyping status of the Helicobacter pylori strains isolated from human and animal gastric biopsy samples.

Patients and methods

A total of 1,150 gastric biopsy samples were randomly collected from humans (children and adults) and animals (cows, sheep and goats). All samples were subjected to culture, urease test and histopathologic examination. H. pylori isolates were also confirmed using the 16S rRNA gene PCR-amplification. Antibiotic resistance pattern was assessed by the disk diffusion method. Distribution of different genotypes was studied by PCR.

Results

The prevalence of H. pylori in gastric biopsy samples which were studied using urease test, culture and histological examination were 57.04%, 55.40% and 60.80%, respectively. Samples that were collected from adult humans (78%) and sheep (70%) had the highest prevalence of H. pylori strains, while those of goats (0.6%) and cows (4%) had the lowest. Findings of the culture method were confirmed using PCR-based amplification of 16S rRNA. Distribution of H. pylori among the gastric ulcers, duodenal ulcers, chronic gastritis gastric cancer and chronic cancer samples were 10.40%, 15.70%, 96.50%, 0.60% and 3.14%, respectively. H. pylori strains harbored the highest prevalence of resistance against ampicillin (74.4%), clarithromycin (63.4%), trimethoprim (61.5%) and metronidazole (61.5%). The most commonly detected genotypes among the H. pylori strains isolated from different types of biopsy samples were cagA (84.79%), vacA m2 (55.95%), vacA s1a (49.84%), cagE (48.58%), iceA1 (47.02%) and iceA2 (47.02%).

Conclusion

High prevalence of antibiotic resistance and virulent genotypes indicates an important public health issue. Similarities in antibiotic resistance and genotyping pattern of H. pylori strains isolated from humans and animals may show their similar routes of infection.

Fecal Helicobacter pylori glmM and 16S rRNA genes correlate with serum TNF-α and IL-1β cytokine fluctuations

The proinflammatory cytokines of TNF-α and IL-1β have been reported to be increased in gastric mucosal surfaces in people with Helicobacter pylori infection. Accordingly, this study was conducted to investigate the relationship between the presence of H. pylori genes and the serum oscillations of these cytokines. In this study, DNA was first extracted from the stool samples of infected individuals and used as DNA template to investigate the presence of glmM and 16S rRNA genes in PCR. The ELISA assay was employed to examine serum levels of TNF-α and IL-1β cytokines. According to statistical analysis, there was a significant correlation between the presence of glmM and 16S rRNA genes in the stool samples of infected persons and the serum oscillations of TNF-α and IL-1β cytokines. At the end of study and analysis of the data in case group with HPSAg+, 47.6% of the glmM gene and 23.6% of the 16S rRNA gene were positive. In addition, a significant correlation was observed between the presence of glmM and 16S rRNA genes in the stool specimens of infected individuals and the serum levels of TNF-α and IL-1β cytokines (p < 0.05). Considering the results, it can be concluded that fluctuations in the amount of HPSA, TNF-α, and IL-1β in H. pylori infection depend on the presence of glmM and 16S rRNA genes. The presence of glmM and 16S rRNA in the stool sample increases by boosting the response level to stool antigen (HPSA), IL-1β, and TNF-α, suggesting the prognosis of the disease with a bacterial virulence form using stool tests.

Presence of gastric Helicobacter species in children suffering from gastric disorders in Southern Turkey

BACKGROUND

Infections with gastric Helicobacter spp. are associated with gastritis, peptic ulceration, and malignancies. Helicobacter pylori is the most prevalent Helicobacter species colonizing the human stomach. Other gastric non-H. pylori helicobacters (NHPHs) have been described in 0.2%-6% of human patients with gastric disorders. Nevertheless, due to difficulties in the diagnosis of NHPH infections and lack of routine screening, this is most likely an underestimation of their true prevalence. To the best of our knowledge, no studies have been performed in the presence of Helicobacter spp. in children suffering from gastric disorders in Southern Turkey.

MATERIALS AND METHODS

In total, 110 children with gastric complaints were examined at the Cukurova University Balcali hospital, Turkey. Gastroscopy was performed to evaluate the presence of gastric mucosal lesions. Biopsies of the pyloric gland zone were taken for histopathological analysis, rapid urease testing, and presence of Helicobacter spp. DNA by PCR.

RESULTS

Based on the PCR results, the prevalence of Helicobacter spp. was 32.7% (36/110). H. pylori was found in 30.9% (34/110), H. suis in 1.8% (2/110), and H. heilmannii/H. ailurogastricus in 0.9% (1/110) of the human patients. A mixed infection with H. pylori and H. suis was present in one patient. The presence of mucosal abnormalities, such as nodular inflammation, ulceration, and hyperemia, as well as gastritis, was significantly higher in Helicobacter spp. positive patients.

CONCLUSION

Helicobacter pylori, H. suis, and H. heilmannii/H. ailurogastricus were present in children with gastric complaints. Infection with these pathogens may be involved in the development of gastritis and ulceration.

Prevalence of Helicobacter pylori vacA, cagA, cagE, oipA, iceA, babA2 and babB genotypes in Iranian dyspeptic patients

There is diversity in clinical outcome of Helicobacter pylori infection in different regions. Microbial, host and environmental factors seem to be reason of such variation. Considering microbial factors, we studied H. pylori genotypes and their association with clinical feature of the infection. Overall 160 H. pylori-positive patients were enrolled in this study. Clinical information and biopsy were collected from each patient. The presence of the major virulence genes were determined by PCR. Regardless to clinical outcomes, vacA, cagA, cagE, oipA, iceA1, babA2 and babB genes was positive in 100%, 69%, 51%, 55%, 26%,78% and 28% of 160 strains respectively. The s1m2 was more common vacA allels and s1a and m1a were predominant s and m regions. In patient with gastric cancer (GC), the oipA was less frequent while the iceA1 was the most common. The babA2 was common in all patient groups. The babB was significantly observed in strains isolated from patients with GC. There were significant association among cagA status with presence of vacAs1, vacAm2, cagE, oipA, iceA1 and babA2. Presence of the babB and oipA was connected with higher and lower risk for GC respectively. There was no association between the cagA, vacA, cagE or iceA status and clinical outcome in patients in Iran. We showed that presence of the babB and iceA1 were significantly connected with higher risk for gastric cancer development in Iranian dyspeptic patients while H. pylori isolates with positive oipA had little threat for leading patients to cancer.

Evaluation of Invasive and Noninvasive Methods for the Diagnosis of Helicobacter Pylori Infection

Objective:

The present study was conducted to evaluate invasive and noninvasive diagnostic methods for detection of Helicobacter pylori (H. pylori) in patients admitted with dyspeptic complaints and to compare sensitivities and specificities.

Method:

Sets of four gastric biopsy specimens were obtained from a total of 126 patients included in the study. The presence of H. pylori was determined by invasive tests including culture, rapid urease test, polymerase chain reaction (PCR) and histopathology. Among noninvasive tests, urea breath test, serological tests and enzyme-linked immunosorbent assay (ELISA) were performed.

Results:

H. pylori was isolated in 79 (62.7%) gastric biopsy cultures, whereas positivity was concluded for 105 (83.3%) patients by rapid urease test, for 106 (84.1%) by PCR, for 110 (87.3%) by histopathology, for 119 (94.4%) by urea breath test, and for 107 (84.9%) by ELISA. In the present study, the culture findings and histopathological examination findings were accepted as gold standard. According to the gold standard, urea breath test had the highest sensitivity (96.5%) and the lowest specificity (30%), whereas culture and histopathology had the highest specificities (100%).

Conclusion:

The use of PCR invasively with gastric biopsy samples yielded parallel results with the gold standard. PCR can be recommended for routine use in the diagnosis of H. pylori.

Clinical relevance of Helicobacter pylori virulence factors in Iranian patients with gastrointestinal diseases

Helicobacter pylori (H. pylori) usually colonizes the gastric mucosa of more than 50% of the human population, causing an infection that may appear in early childhood and can persist for life. H. pylori is suggested as the main cause of peptic ulcer and chronic gastritis. It is also associated with gastric cancer. Its severity and symptoms depend on environmental factors, host susceptibility and bacterial components, which allow H. pylori to switch between commensalism and pathogenicity. H. pylori is genetically highly variable, and the variability which affects H. pylori virulence factors might be useful in identifying the strains with different degrees of pathogenicity. The geographic distribution of distinct H. pylori genotypes is largely unknown and should be established. The prevalence of more pathogenic genotypes in certain areas may have important epidemiological consequences. It also might be associated with the severity of H. pylori related diseases in such regions. Given that Iran is located in the Middle East and Asian populations have revealed high levels of gastric cancer, it is of clinical interest to clarify the potential of H. pylori virulence markers in predicting the associated clinical outcomes. In this review, clinical relevance of adhesion molecules and significant virulence factors of H. pylori in Iranian patients with gastrointestinal diseases are discussed in comparison to other countries.

Relevance of Helicobacter pylori vacA 3'-end Region Polymorphism to Gastric Cancer

BACKGROUND

Helicobacter pylori vacA genotypes play an important role in the pathogenesis of severe gastrointestinal disease.

MATERIALS AND METHODS

We identified a novel polymorphic site in the 3'-end region of H. pylori vacA gene, denoted by c1/-c2 (c1: with deletion of 15 bp), and examined associations of this and the previous four sites as well as cagA status with gastroduodenal diseases, in a total of 217 Iranian H. pylori isolates. Histopathologic evaluations were performed and patients with gastric cancer (GC) were further classified based on the anatomic site of tumor, including cardia and noncardia GC, and the histopathologic type of tumor, including intestinal- and diffuse-type GC.

RESULTS

The vacA m1, i1, d1, c1, and cagA genotypes were significantly associated with an increased risk of GC, the odds ratio (95% confidence interval) was 4.29 (2.03-9.08), 6.11 (2.63-14.19), 3.18 (1.49-6.76), 15.13 (5.86-39.01), and 2.59 (1.09-6.12), respectively. The vacA c1 genotype had an increased age- and sex-adjusted risk for GC by the multiple logistic regression analysis; the OR was 38.32 (95% CI, 6.60-222.29). This association was independent of and larger than the associations of the m-, i-, and d-type of vacA or cagA status with GC. No significant correlation was found between s1, whether independently or in combination, and the risk of GC or peptic ulcer disease (PUD). The vacA i1 and cagA genotypes were linked to an increased risk of PUD; the OR (95% CI) was 2.80 (1.45-5.40) and 2.62 (1.23-5.61), respectively. The presence of both the vacA i1 and cagA genotypes further increased the risk of PUD; the OR was 5.20 (95% CI, 1.92-14.03).

CONCLUSION

The H. pylori vacA c1 genotype might therefore be one of the strongest risk predictors of GC in male patients aged ≥55 in Iran.

Helicobacter pylori isolated from Iranian drinking water: vacA, cagA, iceA, oipA and babA2 genotype status and antimicrobial resistance properties

Despite the clinical importance of Helicobacter pylori in human gastric disorders, its exact route of transmission is still uncertain. Based on the contentious hypothesis and findings of previous investigations, water may play an important role in the transmission of H. pylori to humans. This study was carried out to investigate the vacA, cagA, oipA, iceA and babA2 genotype status and antimicrobial resistance properties of H. pylori strains isolated from the drinking water samples of four major provinces in Iran. A total of 400 drinking water samples were cultured and tested. H. pylori-positive strains were analyzed for the presence of various genotypes and antimicrobial resistance. Twelve of 400 (3%) water samples were positive for H. pylori. Samples from Isfahan province had the highest, while those from Shiraz had the lowest prevalence of H. pylori. The seasonal distribution was also determined, with the highest prevalence of bacteria in the summer season (7.36%). H. pylori strains harbored the highest levels of resistance against ampicillin (100%), erythromycin (75%), clarithromycin (75%), and trimethoprim (58.3%). The most commonly detected genotypes were vacAs1a (83.3%), vacAm1a (66.6%), vacAs2 (50%) and cagA (50%). The presence of similar genotypes in the H. pylori strains of drinking water and those of human clinical samples suggest that contaminated water maybe the sources of bacteria. Spiramycin and furazolidone are suggested for the treatment of cases of H. pylori infection.

Helicobacter pylori in bottled mineral water: genotyping and antimicrobial resistance properties

BACKGROUND

Up to now, fecal-oral and oral-oral are the most commonly known routes for transmission of H. pylori, therefore, contaminated water can play an important role in transmission of H. pylori to humans. Genotyping using virulence markers of H. pylori is one of the best approaches to study the correlations between H. pylori isolates from different samples. The present research was carried out to study the vacA, cagA, cagE, oipA, iceA and babA2 genotyping and antimicrobial resistance properties of H. pylori isolated from the bottled mineral water samples of Iran.

RESULTS

Of 450 samples studied, 8 samples (1.77%) were contaminated with H. pylori. Brand C of bottled mineral water had the highest prevalence of H. pylori (3.63%). The bottled mineral water samples of July month had the highest levels of H. pylori-contamination (50%). H. pylori strains had the highest levels of resistance against metronidazole (62.5%), erythromycin (62.5%), clarithromycin (62.5%), amoxicillin (62.5%) and trimethoprim (62.5%). Totally, 12.5% of strains were resistant to more than 6 antibiotics. VvacAs1a (100%), vacAm1a (87.5%), cagA (62.5%), iceA1 (62.5%), oipA (25%), babA2 (25%) and cagE (37.5%) were the most commonly detected genotypes. M1as1a (62.5%), m1as2 (37.5%), m2s2 (37.5%) and S1a/cagA+/IceA2/oipA-/babA2-/cagE- (50%) were the most commonly detected combined genotypes.

CONCLUSIONS

Contaminated bottled mineral water maybe the sources of virulent and resistant strains H. pylori. Careful monitoring of bottled mineral water production may reduce the risk of H. pylori transmission into the human population.

Molecular Epidemiology of Helicobacter pylori Infection in Nepal: Specific Ancestor Root

Prevalence of Helicobacter pylori infection in Nepal, a low-risk country for gastric cancer, is debatable. To our knowledge, no studies have examined H. pylori virulence factors in Nepal. We determined the prevalence of H. pylori infection by using three different tests, and the genotypes of virulence factors were determined by PCR followed by sequencing. Multilocus sequence typing was used to analyze the population structure of the Nepalese strains. The prevalence of H. pylori infection in dyspeptic patients was 38.4% (56/146), and was significantly related with source of drinking water. In total, 51 strains were isolated and all were cagA-positive. Western-type-cagA (94.1%), cagA pre-EPIYA type with no deletion (92.2%), vacA s1a (74.5%), and m1c (54.9%) were the predominant genotypes. Antral mucosal atrophy levels were significantly higher in patients infected with vacA s1 than in those infected with s2 genotypes (P = 0.03). Several Nepalese strains were H. pylori recombinants with genetic features of South Asian and East Asian genotypes. These included all East-Asian-type-cagA strains, with significantly lesser activity and inflammation in the corpus than the strains of the specific South Asian genotype (P = 0.03 and P = 0.005, respectively). Although the population structure confirmed that most Nepalese strains belonged to the hpAsia2 population, some strains shared hpEurope- and Nepalese-specific components. Nepalese patients infected with strains belonging to hpEurope showed higher inflammation in the antrum than strains from the Nepalese specific population (P = 0.05). These results support that ancestor roots of Kathmandu`s people not only connected with India alone.

The clearance effect of bovine anti-Helicobacter pylori antibody-containing milk in O blood group Helicobacter pylori-infected patients: a randomized double-blind clinical trial

BACKGROUND

The failure in standard triple therapy has recently increased to high levels in China, primarily because of insufficient patient compliance, antimicrobial resistance, and high costs. Effective prevention and eradication of Helicobacter pylori (H. pylori) by artificial passive immunization with orally administered bovine antibodies in the milk has been demonstrated in many animal studies, but the clinical studies that are available have shown no H. pylori eradication. This study was to evaluate the efficacy and safety of orally administered bovine anti-H. pylori antibodies for the clearance of H. pylori infecting O blood group subpopulations.

METHODS

Two local epidemic H. pylori strains that were prevalent locally were screened and then used to immunize dairy cows. After confirmation of the presence of anti-H. pylori polyclonal antibodies in the milk by enzyme-linked immunosorbent assay, the milk was subsequently defatted and processed into sterile milk by pasteurization. This study was designed as a double-blind placebo-controlled randomized clinical trial. Our 61 H. pylori-infected O blood group subjects were assigned to two groups; 31 subjects were treated with bovine milk containing antibodies and 30 subjects with the placebo. The medication-based study was continued for 28 days. Subjects were followed up for 56 days. The effect was assessed by the C-14 urea breath test (UBT). SPSS 17.0 software for Windows was used to analyze the data.

RESULTS

Of the 61 subjects enrolled, 58 completed the protocol. One volunteer in the antibodies group and two volunteers in the control group dropped out. Of the 30 antibody-treated subjects, 13 became UBT negative, whereas none of the 30 of the placebo-treated subjects became UBT negative after the medication. Of 13 UBT negative patients, 3 became positive again at the end of the follow-up. Both intention to treat and per-protocol analysis indicated a significant difference in the clearance rate of infected patients between the groups treated with bovine antibody-containing milk and the placebo (P = 0.001, P < 0.05) and no significant difference in adverse effects (P > 0.05 all).

CONCLUSIONS

Bovine antibody-based oral immunotherapy appears to be safe and has a significant clearance effect on intragastric H. pylori that infects O blood group adults.

TRIAL REGISTRATION

ChiCTR-TRC-14005212.

Prevalence of Helicobacter pylori in children in eastern Turkey and molecular typing of isolates

The objectives of the present study were to determine Helicobacter pylori via culture, polymerase chain reaction and histopathological diagnosis in 101 children ranging in age from 4 to 18 years, to identify the association among restriction fragment length polymorphism types and clinical disease and to investigate the relationships among different isolates of H. pylori in different age groups. We observed a high prevalence of H. pylori infections in children between the ages of 13 and 18 (75.8%), while children aged 4 to 6 years had the lowest prevalence of infection (40%). H. pylori was detected in 30.7% (31 of 101), 66.3% (67 of 101) and 63.2% (60 of 95) of children as determined by culture methods, PCR and histological examination, respectively. H. pylori isolates with RFLP types I and III were the most common among children with antral nodularity, whereas RFLP types II and IV were the least detected types. Interestingly, all isolates from peptic ulcer patients were type III. Although our results show a high prevalence of H. pylori infections in the pediatric population in eastern Turkey, no association was identified between H. pylori infection with antral nodularity and recurring abdominal pain. In addition, we found low genetic variation among H. pylori isolates from children and no association between RFLP types and antral nodularity (p > 0.05). Additionally, we found that H. pylori isolates with specific RFLP types were predominant in different age groups.

Duodenal ulcer promoting gene 1 (dupA1) is associated with A2147G clarithromycin-resistance mutation but not interleukin-8 secretion from gastric mucosa in Iraqi patients

Helicobacter pylori causes peptic ulceration and gastric adenocarcinoma. The aims were to study the influence of dupA1 positivity upon interleukin-8 (IL-8) secretion from gastric mucosa and determine the prevalence of mutations responsible for clarithromycin and fluoroquinolone resistance. DNA was extracted from 74 biopsies and the virulence factors were studied. Levels of IL-8 in gastric mucosa were measured using ELISA and the mutations responsible for clarithromycin and fluoroquinolone resistance were determined using a GenoType-HelicoDR assay. The prevalence of cagA in strains isolated from gastric ulcer (GU) and duodenal ulcer (DU) was significantly higher than those isolated from non-ulcer disease (NUD) (90% and 57.9% versus 33.3%; p 0.01). The vacA s1m1 genotype was more prevalent in patients with DU (73.7%) and GU (70%) than in those with NUD (13.3%) (p 0.01). The prevalence of dupA1 was higher in DU patients (36.8%) than those with GU (10%) and NUD (8.9%) (p 0.01). Multivariate analysis showed that a cagA+/vacA s1i1m2 virulence gene combination was independently associated with the developing peptic ulcer disease (PUD) with increased odds of developing PUD (p 0.03; OR = 2.1). We found no significant difference in the levels of IL-8 secretion in gastric mucosa infected with H. pylori dupA-negative and H. pylori dupA1-positive strains (dupA-negative: mean ± median: 28 ± 26 versus 30 ± 27.1 for dupA1; p 0.6). While 12 strains were clarithromycin resistant, only three isolates were levofloxacin resistant. A significant association was found between dupA1 genotype and A2147G clarithromycin resistance mutation (p <0.01). Further study is needed to explore the relationship between virulence factors and disease process and treatment failure.

Friend and foe: factors influencing the movement of the bacterium Helicobacter pylori along the parasitism-mutualism continuum

Understanding the transition of bacterial species from commensal to pathogen, or vice versa, is a key application of evolutionary theory to preventative medicine. This requires working knowledge of the molecular interaction between hosts and bacteria, ecological interactions among microbes, spatial variation in bacterial prevalence or host life history, and evolution in response to these factors. However, there are very few systems for which such broad datasets are available. One exception is the gram-negative bacterium, Helicobacter pylori, which infects upwards of 50% of the global human population. This bacterium is associated with a wide breadth of human gastrointestinal disease, including numerous cancers, inflammatory disorders, and pathogenic infections, but is also known to confer fitness benefits to its host both indirectly, through interactions with other pathogens, and directly. Outstanding questions are therefore why, when, and how this bacterium transitions along the parasitism–mutualism continuum. We examine known virulence factors, genetic predispositions of the host, and environmental contributors that impact progression of clinical disease and help define geographical trends in disease incidence. We also highlight the complexity of the interaction and discuss future therapeutic strategies for disease management and public health in light of the longstanding evolutionary history between the bacterium and its human host.

Coextraction and PCR Based Analysis of Nucleic Acids From Formalin-Fixed Paraffin-Embedded Specimens

BACKGROUND

Retrospective studies of archived human specimens, with known clinical follow-up, are used to identify predictive and prognostic molecular markers of disease. Due to biochemical differences, however, formalin-fixed paraffin embedded (FFPE) DNA and RNA have generally been extracted separately from either different tissue sections or from the same section by dividing the digested tissue. Our optimized co-extraction approach provides the option of collecting DNA, which would otherwise be discarded or degraded, for additional or subsequent studies because of the high importance and less availability of clinical FFPE specimen.

METHODS

Coextraction of DNA and RNA from a single gastric cancer FFPE specimen was optimized by using TRIzol and purifying DNA from the lower aqueous and RNA from the upper organic phases. The protocol involves modification of incubation period for 30 min with proteinase K in glycin-tris-ethylenediamine tetra acetic acid buffer before adding TRIzol.

RESULTS

All samples tested successfully performed semiquantitative gene expression by reverse transcriptase PCR. The quantity and quality of DNA from FFPE samples was high which resulted in successful PCR amplification. The isolated DNA also aided in detection of Helicobacter pylori by amplifying the ribosomal 16S gene in a multiplex PCR reaction along with cagA.

CONCLUSION

These results show that the RNA/DNA isolated by this method can be used for easy clinical diagnosis of disease-related gene expression as well as mutation and pathogen detection from a homogenous population of tumor cells.

Helicobacter pylori CagA and VacA genotypes and gastric phenotype: a meta-analysis

BACKGROUND

CagA+ and vacuolizing cytotoxin (VacA)-specific strains of Helicobacter pylori have been associated with different risks for developing gastric lesions. We aim to summarize a possible association between these genotypes and the risk for developing different gastric phenotypes.

MATERIALS AND METHODS

A MEDLINE database (PubMed) search was performed and a meta-analysis conducted.

RESULTS

Forty-four studies were retrieved, all with either a case-control (n=13) or cross-sectional (n=31) design, including 17 374 patients. CagA positivity was associated with an increased risk for gastric cancer [odds ratio (OR) 2.09 (95% confidence interval (CI), 1.48-2.94)] compared with that in individuals without gastric lesions [OR 2.44 (95% CI 1.27-4.70)] and in those with previously identified gastritis. In addition, there was an increased risk for peptic ulcer disease [OR 1.69 (95% CI 1.12-2.55)]. Individuals harboring the H. pylori strains VacA s1 (vs. s2), m1 (vs. m2), s1m1 (vs. s1m2), and s1m1 (vs. s2m2) had an increased risk for development of cancer [OR of 5.32 (95% CI 2.76-10.26), 2.50 (95% CI 1.67-3.750), 2.58 (95% CI 1.24-5.38), and 4.36 (95% CI 2.08-9.10), respectively]. s1m1 strains (vs. s2m2) were also associated with peptic ulcer disease [OR 2.04 (1.01-4.13)].

CONCLUSION

Our results indicate that individuals infected with CagA+ H. pylori strains and those infected with VacA s1 and m1 strains have an increased risk for gastric cancer. Cohort studies are welcome to integrate this information in the management of at-risk individuals such as those with precancerous cancer conditions and/or a family history of gastric cancer.

Association between Helicobacter pylori, cagA, and vacA Status and Clinical Presentation in Iranian Children

OBJECTIVE

Seroprevalence of H. pylori infection in Iran exceeds 65% of pediatric population. In this study, we intended to find association between the virulence genes (cagA and vacA) and clinical presentations.

METHODS

H. pylori isolates were achieved from the gastric mucosa of children. In each case, the gastric biopsy specimens were cultured and the organisms identified. Detection of different genotypes was carried out by PCR method.

FINDINGS

A total of 106 biopsy specimens were cultured and 33 H. pylori isolates obtained. Among these 33 H. pylori strains 24 (73%) were cagA-positive. Genotypes of vacA s1m2, s1m1, s2m2, and s2m1 were 45.5%, 30.3%, 21.2%, and 3%, respectively. Most female patients were infected with genotype s1m2. The vacA-m1 strains were significantly more common in patients with nodular gastritis. There were no statistical differences between the vacA and cagA genotypes and clinical outcomes.

CONCLUSION

The frequency of cagA genotype was high. In this study, nodular gastritis was a common finding and was rather significantly associated with m1 allele of vacA.

The distribution of cagA and dupA genes in Helicobacter pylori strains in Kurdistan region, northern Iraq

BACKGROUND AND OBJECTIVES

Helicobacter pylori is a Gram negative bacteria that causes peptic ulceration and gastric adenocarcinoma. H pylori virulence factors, such as cagA and dupA, are important to study in populations as they contribute to disease risk. This study aimed to look at the distribution of the cagA and dupA genes in H pylori strains isolated from patients suffering from gastroduodenal diseases in Kurdistan region, Iraq.

DESIGN AND SETTINGS

A cross-sectional study conducted between June 2011 and January 2012. Biopsies were collected from the Endoscopy Department in Duhok and Sulaimania hospitals, Kurdistan region, northern Iraq.

PATIENTS AND METHODS

Upper gastrointestinal (GI) endoscopy examination was performed and 4 gastric biopsies (2 from the antrum and 2 from the corpus) were obtained from 204 patients. H pylori positivity was examined by CLO test; then the association between disease status and virulence factors was assessed by polymerase chain reaction.

RESULTS

154 (75%) of our samples were found to be H pylori + by CLO test. Endoscopic diagnoses for those who were positive were as follows: peptic ulcer disease (PUD) including duodenal ulcer, 45; gastric ulcer, 23; and no ulcer (NPUD), 86. The overall prevalence rates of cagA and dupA were 72.7% and 18.8%, respectively. While a significant association between cagA and PUD was observed (P. ≤.017; OR=0.4; CI=0.18–0.85), no relationship between dupA and PUD could be seen.

CONCLUSION

These data suggested that the presence of cagA may be a predictor of clinical outcome in Kurdistan region, northern Iraq.

Diversity of Helicobacter Pylori cagA and vacA Genes and Its Relationship with Clinical Outcomes in Azerbaijan, Iran

PURPOSE

The purpose of this research was to analyze cagA and vacA genotypes status in H. pylori isolates and relationship with clinical outcomes.

METHODS

Gastric biopsy specimens were cultured for H. pylori isolation and cagA and vacA genes were detected in these isolates. Data were collected and the results were analyzed using χ2 and Fishers exact tests by SPSS software version. 16.

RESULTS

Of the total 115 H. pylori isolates, 79 (68.7 %) were cagA positive and 82 (71.3%) of isolates contained the s1 allele which 33 (28.7%) were subtype s2. s1m2 was the most frequent vacA allelic combination in the H. pylori isolates examined (63 cases), followed by s2m2 (31 cases), s1m1 (19 cases) and s2m1 (2 case). Strains cagA positive were more frequent in peptic ulcer diseases patients than non ulcer diseases patients, as 47 (59.5%) and 32 (40.5%), while cagA negative were low, as 15 (41.7%) and 21 (58.3%), respectively.

CONCLUSION

We found that the cagA and vacA status were not related to clinical outcomes in this area. Overall, in the present study, vacA s1/m2, cagA-positive strains were predominant irrespective of clinical outcome, but s2/m1 was rare.

Infection with Helicobacter pylori strains carrying babA2 and cagA is associated with an increased risk of peptic ulcer disease development in Iraq

BACKGROUND AND STUDY AIM

Several genes of Helicobacter pylori, such as vacA, cagA, iceA and babA, have been reported to significantly increase the risk of gastrointestinal diseases. The aim of this study was to study the relationship between H. pylori virulence factors and clinical outcomes and identify the independent markers of peptic ulcer disease in Iraq.

PATIENTS AND METHODS

DNA was extracted from specimens taken from 154 unselected H. Pylori positive Iraqi patients. Genotyping was performed by the polymerase chain reaction (PCR), using specific primers for cagA, vacA (s, m), iceA and babA2 genes.

RESULTS

A total of 56 (82%) peptic ulcer disease (PUD) patients carried cagA+ strains, significantly more than the 56 (65%) non-ulcer disease (NUD) patients (p=0.017). The difference in the prevalence of babA2 positivity was significant between patients with NUD (33.7%) and PUD (58.8%) (p=0.002). In addition, babA2 was associated as an independent factor, with PUD (p=0.005; odds ratio (OR)=0.4; confidence interval (CI)=0.18-0.68) followed by cagA (p=0.05; OR=0.4; CI=0.18-0.85). Forty-five isolates (29%) were typed as 'triple positive' strains, and their presence was significantly associated with PUD (p=0.001).

CONCLUSION

The cagA and babA2 genotypes might be considered as useful markers for PUD patients. However, iceA1 and iceA2 seem not to be good markers for the disease. The presence of H. pylori strains with triple-positive status is of high clinical relevance to H. pylori-associated diseases.

Prevalence of genotypes in Helicobacter pyloriisolates from patients in eastern Turkey and the association of these genotypes with clinical outcome

There is not much information available regarding the prevalence of the genotypes of Helicobacter pylori isolates in Turkey, particularly in eastern Turkey. The aims of this study were to detect the prevalence of different genotypes of H. pylori in Turkish patients with gastrointestinal complaints and to determine the relationship of these genotypes with clinical outcome and sex. One hundred forty H. pylori isolates were examined for the presence of its genotypes by the PCR. We found that the prevalence of vacAs1,vacAs2, cagA, cagE, iceA1, iceA2 and babA2 genes were 88.6%, 11.4%, 71.4%, 35.7%, 41.4%, 58.6%, and 62.1%, respectively. The most predominant vacA subtype was s1a (81.4%). The most vacA allelic combination detected were vacAs1m1 (65.2%) and s1m2 (53.9%) in patients with peptic ulcer and gastritis, respectively. The only vacAs1 isolate was significantly associated with gastritis and peptic ulcer (p<0.05). The vacAs1a, ml, slml and babA2 genes were significantly associated with peptic ulcer (p<0.05), whereas m2 gene was significantly associated with only gastritis (p<0.05). The difference between sex and genotypes was statistically significant among the cagA,vacAs1, iceA2 and babA2 genes. This study reported for the first time the prevalence of H. pylori genotypes in patients with gastrointestinal complaints in eastern Turkey. Further studies are needed to understand epidemiological importance of the genotypes of H. pylori isolates in this region and the association between the virulence genes and clinical outcome in different regions.

Prevalence of genotypes in Helicobacter pyloriisolates from patients in eastern Turkey and the association of these genotypes with clinical outcome

There is not much information available regarding the prevalence of the genotypes of Helicobacter pylori isolates in Turkey, particularly in eastern Turkey. The aims of this study were to detect the prevalence of different genotypes of H. pylori in Turkish patients with gastrointestinal complaints and to determine the relationship of these genotypes with clinical outcome and sex. One hundred forty H. pylori isolates were examined for the presence of its genotypes by the PCR. We found that the prevalence of vacAs1,vacAs2, cagA, cagE, iceA1, iceA2 and babA2 genes were 88.6%, 11.4%, 71.4%, 35.7%, 41.4%, 58.6%, and 62.1%, respectively. The most predominant vacA subtype was s1a (81.4%). The most vacA allelic combination detected were vacAs1m1 (65.2%) and s1m2 (53.9%) in patients with peptic ulcer and gastritis, respectively. The only vacAs1 isolate was significantly associated with gastritis and peptic ulcer (p<0.05). The vacAs1a, ml, slml and babA2 genes were significantly associated with peptic ulcer (p<0.05), whereas m2 gene was significantly associated with only gastritis (p<0.05). The difference between sex and genotypes was statistically significant among the cagA,vacAs1, iceA2 and babA2 genes. This study reported for the first time the prevalence of H. pylori genotypes in patients with gastrointestinal complaints in eastern Turkey. Further studies are needed to understand epidemiological importance of the genotypes of H. pylori isolates in this region and the association between the virulence genes and clinical outcome in different regions.

Detection of primary clarithromycin resistance of Helicobacter pylori and association between cagA (+) status and clinical outcome

Helicobacter pylori was examined in 110 patients (82 (74.5) with gastritis, 18 (16.4) with duodenitis, six (5.5) with duodenal ulcer and gastroesophageal reflux, and four (3.6 %) with normal) with gastrointestinal problems living in rural area, no history of macrolide use, and detected by culture (71.8) or direct detection from gastric biopsies by PCR (82.7 %). Also, cagA gene was identified using PCR and was found positive in 68/91 (74.7 %) strains. The prevalence of clarithromycin-resistant H. pylori was investigated by two methods including PCR-RFLP (7.7 (A2142G 1.1 and A2143G 6.6 %)) and twofold agar dilution (8.9 %) to detect phenotypic and genotypic status simultaneously. Among all the H. pylori positive patients, eight (8.8 %) isolates were found to be resistant to clarithromycin by at least one of the AD and/or PCR-RFLP methods. H. pylori positive rates were significantly correlated with patients' sex, age, and endoscopic findings (p = 0.040, <0.001 and <0.001, respectively). There were no differences in gender or endoscopic findings related to cagA (+) and cagA (-) patients. The gene of cagA was not significantly helpful in predicting the clinical outcome of H. pylori infection alone. In conclusion, we revealed that there was a low prevalence of primer clarithromycin resistance in patients living in rural area with no history of macrolide use. The prevalence of mutant strains among the macrolide-resistant H. pylori varies even geographically between close provinces.

Study of Helicobacter pylori genotype status in saliva, dental plaques, stool and gastric biopsy samples

AIM: To compare genotype of Helicobacter pylori (H. pylori) isolated from saliva, dental plaques, gastric biopsy, and stool of each patient in order to evaluate the mode of transmission of H. pylori infection.

METHODS: This cross-sectional descriptive study was performed on 300 antral gastric biopsy, saliva, dental plaque and stool samples which were obtained from patients undergoing upper gastrointestinal tract endoscopy referred to endoscopy centre of Hajar hospital of Shahrekord, Iran from March 2010 to February 2011. Initially, H. pylori strains were identified by rapid urease test (RUT) and polymerase chain reaction (PCR) were applied to determine the presence of H. pylori (ureC) and for genotyping of voculating cytotoxin gene A (vacA) and cytotoxin associated gene A (cagA) genes in each specimen. Finally the data were analyzed by using statistical formulas such as Chi-square and Fisher’s exact tests to find any significant relationship between these genes and patient’s diseases. P < 0.05 was considered statistically significant.

RESULTS: Of 300 gastric biopsy samples, 77.66% were confirmed to be H. pylori positive by PCR assay while this bacterium were detected in 10.72% of saliva, 71.67% of stool samples. We were not able to find it in dental plaque specimens. The prevalence of H. pylori was 90.47% among patients with peptic ulcer disease (PUD), 80% among patients with gastric cancer, and 74.13% among patients with none ulcer dyspepsia (NUD) by PCR assay. The evaluation of vacA and cagA genes showed 6 differences between gastric biopsy and saliva specimens and 11 differences between gastric and stool specimens. 94.42% of H. pylori positive specimens were cagA positive and all samples had amplified band both for vacA s and m regions. There was significant relationship between vacA s1a/m1a and PUD diseases (P = 0.04), s2/m2 genotype and NUD diseases (P = 0.05). No statically significant relationship was found between cagA status with clinical outcomes and vacA genotypes (P = 0.65). The evaluation of vacA and cagA genes showed 6 differences between gastric biopsy and saliva specimens and 11 differences between gastric and stool specimens.

CONCLUSION: Regard to high similarity in genotype of H. pylori isolates from saliva, stomach and stool, this study support the idea which fecal- oral is the main route of H. pylori transmission and oral cavity may serve as a reservoir for H. pylori, however, remarkable genotype diversity among stomach, saliva and stool samples showed that more than one H. pylori genotype may exist in a same patient.

Differential expression of MYC in H. pylori-related intestinal and diffuse gastric tumors

Evidence suggests that the carcinogenic process guided by Helicobacter pylori is related to the expression of cell cycle and apoptosis proteins as BCL-2, BAX, and MYC. However, the literature is conflicting regarding the expression frequency in the histological subtypes and did not consider cagA gene presence. To investigate the expression of these proteins considering the histological subtypes of gastric cancer associated with H. pylori (cagA), a total of 89 cases were used. H. pylori infection and cagA status were determined by PCR. Immunodetection was performed for MYC, BCL-2, and BAX proteins. H. pylori was found in 95.5% of the patients, among them, 65.8% were cagA(+). Nuclear MYC was detected in 36.4%, BAX in 55.7%, while BCl-2 in just 5%. Nuclear MYC staining was significantly lower in the intestinal than diffuse subtype (p = 0.008) and was related with the presence of H. pylori cagA(+). Additionally, most of the few cases cytoplasmic MYC positive were in the intestinal subtype. In diffuse tumors, although most nuclear MYC positive cases were cagA(+), it was not significant. No difference was observed between BCL-2 or BAX expression considering the presence of cagA gene in the histological subtypes. It seems that MYC could be relevant for the diffuse tumorigenic pathway associated with H. pylori and possibly influenced by the presence of cagA gene, while in intestinal tumors, the tumorigenic pathway does not occur through the MYC expression.

Prevalence of Helicobacter pylori genotypes (vacA, cagA, cagE and virB11) in gastric cancer in Brazilian's patients: an association with histopathological parameters

PURPOSE

To investigate the frequency and the association of vacA alleles, cagA, cagE and virB11 genes of Helicobacter pylori from patients with gastric cancer, considering the clinic histopathological parameters.

METHODS

One hundred and one gastric adenocarcinoma tissues were assessed by PCR to detect H. pylori and vacA alleles, cagA, cagE and virB11.

RESULTS

The distribution of cases according to the presence of the genes studied showed that the group containing vacA s1m1, cagA, cagE and virB11 H. pylori genes was significantly more frequent, followed by the group with at least one marker on the right side and left of the island. They were also present in the early stages and were the most frequent in nearly all histopathological grades.

CONCLUSIONS

This study verified that vacAs1m1 and cag-PAI genes, cagA, cagE and virB11 are important H. pylori markers for gastric cancer development. Also, this study corroborates the importance of cagE and cagA together as cag-PAI marker.

Coevolution and adaptation of Helicobacter pylori and the case for 'functional molecular infection epidemiology'

Helicobacter pylori is a major human pathogen and its transmission and epidemiology have been extensively studied; it has been found that H. pylori's prevalence and infection outcome is characterized by marked differences between the developing and the developed worlds. Recent data on genomic analyses and comparative core genome haplotyping have revealed that H. pylori has coevolved with its human host. While several studies advocate the protective effects of H. pylori colonization, it is prudent to systematically unleash the role of the strong virulence apparatus present within most H. pylori strains and to determine how to disarm them (or protect the host from the effects) if the intent is to allow it to remain a friendly organism or to use it as a vaccine delivery tool. While genotyping and phenotyping based on a few genetic markers have not provided much insight into such issues, use of replicate/chronological genomics (of virulent versus innocuous strains) coupled with functional screens in animal models is expected to be able to explain the acquisition and evolution of virulence factors of H. pylori and their discreet associations with serious clinical outcomes such as gastric cancer.

Mechanisms of disease: Helicobacter pylori virulence factors

Helicobacter pylori plays an essential role in the development of various gastroduodenal diseases; however, only a small proportion of people infected with H. pylori develop these diseases. Some populations that have a high prevalence of H. pylori infection also have a high incidence of gastric cancer (for example, in East Asia), whereas others do not (for example, in Africa and South Asia). Even within East Asia, the incidence of gastric cancer varies (decreasing in the south). H. pylori is a highly heterogeneous bacterium and its virulence varies geographically. Geographic differences in the incidence of gastric cancer can be explained, at least in part, by the presence of different types of H. pylori virulence factor, especially CagA, VacA and OipA. However, it is still unclear why the pathogenicity of H. pylori increased as it migrated from Africa to East Asia during the course of evolution. H. pylori infection is also thought to be involved in the development of duodenal ulcer, which is at the opposite end of the disease spectrum to gastric cancer. This discrepancy can be explained in part by the presence of H. pylori virulence factor DupA. Despite advances in our understanding of the development of H. pylori-related diseases, further work is required to clarify the roles of H. pylori virulence factors.

Mechanisms of disease: Helicobacter pylori virulence factors

Helicobacter pylori plays an essential role in the development of various gastroduodenal diseases; however, only a small proportion of people infected with H. pylori develop these diseases. Some populations that have a high prevalence of H. pylori infection also have a high incidence of gastric cancer (for example, in East Asia), whereas others do not (for example, in Africa and South Asia). Even within East Asia, the incidence of gastric cancer varies (decreasing in the south). H. pylori is a highly heterogeneous bacterium and its virulence varies geographically. Geographic differences in the incidence of gastric cancer can be explained, at least in part, by the presence of different types of H. pylori virulence factor, especially CagA, VacA and OipA. However, it is still unclear why the pathogenicity of H. pylori increased as it migrated from Africa to East Asia during the course of evolution. H. pylori infection is also thought to be involved in the development of duodenal ulcer, which is at the opposite end of the disease spectrum to gastric cancer. This discrepancy can be explained in part by the presence of H. pylori virulence factor DupA. Despite advances in our understanding of the development of H. pylori-related diseases, further work is required to clarify the roles of H. pylori virulence factors.

cagA and vacA status and influence of Helicobacter pylori infection on serum oxidative DNA damage in Iranian patients with peptic ulcer disease

BACKGROUND

Infection with Helicobacter pylori strains may result in different pathological manifestations and increased oxidative stress leading to a strong inflammatory response in gastric mucosa.

AIMS

The prevalence of cagA and vacA genes, proteins and the association of serum levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) with oxidative DNA damage were determined.

METHODS

The presence of cagA gene and vacA alleles and IgG antibodies against CagA and VacA proteins were determined. Oxidative DNA damage status was determined using serum levels of 8-OHdG.

RESULTS

Helicobacter pylori-positive, cagA-positive, and vacA alleles (s1 and m2) were predominant in all clinical outcomes. There was no significant association between prevalence of CagA and VacA status and clinical outcomes. The serum levels of 8-OHdG was at a higher level in H. pylori-positive patients.

CONCLUSIONS

These virulence factors are not associated with the development of PUD in Iranian patients. H. pylori infection may be associated with increased serum 8-OHdG.

Helicobacter pylori and gastric cancer in the Middle East: A new enigma?

The Middle East is the home of ethnic groups from three main backgrounds: Semitic (Arabs and Jews), Indo-European (Persians and Kurdish) and Turkic (Turkish and Turkmens). Its geographic location, which has been under continuous influences from Asia, Europe and Africa, has made it an ideal site for epidemiological studies on Helicobacter pylori (H. pylori) infection and genotyping. The gastric cancer rate differs in this region from very high in Iran (26.1/10⁵) to low in Israel (12.5/10⁵) and very low in Egypt (3.4/10⁵). Epidemiological studies showed that the prevalence of H. pylori is almost similar in those countries with a high level of infection in childhood. Importantly, the frequency of vacA s1 and m1 regions and cagA+ genotypes were higher in non Semitic populations who inhabit the North than Semitic populations, the inhabitants of Southern parts of the Middle East. H. pylori infection prevalence, distribution pattern of virulence factors, diet and smoking could not have explained the difference in cancer rate. This reflects the multifactorial aetiology of gastric cancer and suggests that H. pylori infection does not always directly correlate with the risk for gastrointestinal disease, such as gastric cancer. Further detailed investigations and international comparative studies of each risk factor need to be performed to investigate whether this represents a true enigma.