Characterization of Helicobacter pylori cagA and vacA genotypes among Alaskans and their correlation with clinical disease. J Clin Microbiol. 2011;49:3114-3121. [PMID: 21752979 DOI: 10.1128/jcm.00469-11]

The prevalence and risk factors of Helicobacter pylori infection and cagA virulence gene carriage in adults in the Navajo Nation

Background

American Indian and Alaska Native people in the United States experience high rates of stomach cancer. Helicobacter pylori infection is a significant risk factor for stomach cancer, and H. pylori strains that carry the cagA gene are linked to greater gastrointestinal disease severity. Yet, little is known about H. pylori and cagA infections in American Indian and Alaska Native people, particularly at the tribal level. We assessed the prevalence and risk factors of H. pylori infection and cagA gene carriage in tribal members from the Navajo Nation.

Materials and Methods

We conducted a cross-sectional study with adults from the Navajo Nation. Stool samples collected from participants were analyzed with droplet digital PCR for H. pylori 16S ribosomal and cagA virulence genes. Self-administered health and food questionnaires were mailed to participants to collect information on sociodemographic, health, lifestyle, and environmental risk factors for H. pylori infection. Logistic regression assessed the association between risk factors and H. pylori infection and cagA gene carriage.

Results

Among 99 adults, the median age was 45 (age range: 18 to 79 years), and 73.7% were female. About 56.6% (95% CI: 46.2-66.5) of participants were infected with H. pylori. Of H. pylori-infected participants, 78.6% (95% CI: 65.6-88.4) were cagA-gene positive. No significant associations of relevant risk factors with H. pylori and cagA-gene positive infections were noted.

Conclusions

In a community-based study population, a substantial proportion of adult tribal members had H. pylori and cagA-gene positive infections. Given these high proportions, culturally appropriate prevention strategies and interventions addressing H. pylori infections present an avenue for additional research and stomach cancer prevention in the Navajo Nation.

Genetic diversity of Helicobacter pylori type IV secretion system cagI and cagN genes and their association with clinical diseases

A number of cagPAI genes in the Helicobacter pylori genome are considered the most evolved genes under a diversifying selection and evolutionary pressure. Among them, cagI and cagN are described as a part of the two different-operon of cagPAI that are involved in the T4SS machinery, but the definite association of these factors with clinical manifestations is still unclear. A total of 70 H. pylori isolates were obtained from different gastroduodenal patients. All isolates were examined for the presence of primary H. pylori virulence genes by PCR analysis. Direct DNA sequence analysis was performed for the cagI and cagN genes. The results were compared with the reference strain. The cagI, cagN, cagA, cagL, vacA s1m1, vacA s1m2, vacA s2m2, babA2, sabA, and dupA genotypes were detected in 80, 91.4, 84, 91.4, 32.8, 42.8, 24.4, 97.1, 84.3, and 84.3% of the total isolates, respectively. The most variable codon usage in cagI was observed at residues 20-25, 55-60, 94, 181-199, 213-221, 241-268, and 319-320, while the most variable codon usage in CagN hypervariable motif (CagNHM) was observed at residues 53 to 63. Sequencing data analysis of cagN revealed a hypothetical hexapeptide motif (EAKDEN/K) in residues of 278-283 among six H. pylori isolates, which needs further studies to evaluate its putative function. The present study demonstrated a high prevalence of cagI and cagN genes among Iranian H. pylori isolates with gastroduodenal diseases. Furthermore, no significant correlation between cagI and cagN variants and clinical diseases was observed in the present study. However, all patients had a high prevalence of cagPAI genes including cagI, cagN, cagA, and cagL, which indicates more potential role of these genes in disease outcome.

Correlation analysis of gastric mucosal lesions with Helicobacter pylori infection and its virulence genotype in Guiyang, Guizhou province, China

Background

Helicobacter Pylori (H. pylori) infection is the most important factor affecting clinical outcome in patients with gastric mucosal lesions. This study aimed to investigate H. pylori infection in patients with gastric mucosal lesions and their virulence genotype in Guiyang, China.

Methods

Pathological examinations of 1,364 biopsies from patients with upper gastrointestinal symptoms and H. pylori infection were analyzed according to different pathological types. The bacterial genome DNA was extracted from H. pylori strains isolated from gastric biopsies, and the cagA, vacA, and iceA virulence genes were detected and typed to analyze the correlation of their genotypes between different pathological lesions.

Results

The positive rate of H. pylori infection was approximately 19.9% (272/1,364), as determined by histopathological examination (HPE). It was more frequently detected in men than in women. A total of 85 H. pylori isolates were obtained from 280 clinical samples (positive rate 30.4%, 85/280). Of these 85 strains, cagA, vacA, and iceA genes were identified in 85.9%, 100%, and 83.5% of samples, respectively. Approximately 74.1% of strains were cagA East Asian type (cagA-ABD), and 11.8% of were cagA Western strains (cagA-AB, cagA-ABC), only present in patients with chronic non-atrophic gastritis. Gastric intraepithelial neoplasia and gastric cancer harbored both Asian strains. A total of 7 combinations of vacA genotypes were noted, among which s1c/m1b (30.6%) and s1c/m2 (41.2%) were the dominant genotypes. The predominant iceA genotype was iceA1 (64.7%).

Conclusions

We observed that the positive rate of H. pylori infection was related to the pathological type of patients' gastric mucosal lesions. Isolated H. pylori strains showed a unique genotype, mainly East Asian type cagA (ABD), vacA s1c/m2 genotype, and iceA1. These results provide an important reference for further studies of H. pylori in Guizhou province, China.

Helicobacter pylori in Native Americans in Northern Arizona

Background: In Arizona Helicobacter pylori prevalence of infection among Navajo adults is about 62% and gastric cancer incidence rate is 3–4 times higher than that of the non-Hispanic White population. Aim: The aim of this study was to estimate the prevalence of specific H. pylori virulence factors (cagA and vacA) among Navajo patients undergoing and their association with gastric disease. Methods: Virulence genes, cagA and vacA, in H. pylori were investigated in gastric biopsies from 96 Navajo patients over age 18 who were undergoing esophagogastroduodenoscopy. Biopsies from the antrum and fundus were used for molecular characterization to determine cagA type and number of EPIYA motifs and presence of alleles in the signal (s) and medium (m) regions of the vacA gene. Results: H. pylori infection was found in 22.9% of the biopsy samples. The cagA gene amplified in 57.6% of samples and showed a predominant “Western cagA” type, with the EPIYA-ABC motif (45.4%), most prevalent. The vacA allele s1bm1 was the most prevalent (54.5%). Conclusions: H. pylori genotypes were predominantly cagA Western-type and ABC EPIYA motifs. The vacA s1bm1 genotype was the most prevalent and seemed to be associated with gastritis. American Indian/Alaska Native populations are at higher risk for gastric cancer. It is important to identify genotypes of H. pylori and virulence factors involved in the high prevalence of H. pylori and associated disease among the Navajo population.

The Relation Between Host TLR9 -1486T/C, rs187084 Gene Polymorphisms and Helicobacter pylori cagA, sodB, hsp60, and vacA Virulence Genes among Gastric Cancer Patients

To identify the associations between different genotypes of TLR9 -1486T/C (rs187084) with gastric cancer patients and reveal their relation to Helicobacter pylori virulence genes (cagA, sodB, hsp60 and vacA). Patients with gastric cancer were recruited to our study, diagnosed both endoscopically and histopathologically. H. pylori were isolated from gastric samples by culture and PCR amplification of the glmM gene. Virulence genes cagA, sodB, hsp60, and vacA were detected by multiplex PCR. Blood samples were used for genotyping of TLR9 -1486T/C (rs187084) by PCR-RFLP. Out of 132 patients with gastric cancer, 106 (80.3%) were positive for H. pylori. A similar number of healthy participants was recruited as controls. The prevalence of cagA, sodB, hsp60, and vacA genes among H. pylori was 90.6%, 70.8%, 83.0%, and 95.3%, respectively. The vacA gene alleles had a prevalence of 95.3% for vacAs1/s2, 52.8% for vacAm1, and 42.5% for vacAm2. The CC genotype of TLR9 -1486T/C had a significantly higher frequency in gastric cancer patients when compared to healthy participants (p = 0.045). Furthermore, the CC genotype demonstrated a significant association with H. pylori strains carrying sodB, hsp60, and vacAm1 virulence genes (p = 0.021, p = 0.049, and p = 0.048 respectively). Patients with CC genotype of TLR9 -1486T/C (rs187084) might be at higher risk for the development of gastric cancer, and its co-existence with H. pylori strains carrying sodB, hsp60, or vacAm1 virulence genes might have a synergistic effect in the development of gastric cancer. Further studies on a wider scale are recommended.

Interruption of Helicobacter pylori-Induced NLRP3 Inflammasome Activation by Chalcone Derivatives

Helicobacter pylori causes chronic gastritis through cag pathogenicity island (cagPAI), vacuolating cytotoxin A (VacA), lipopolysaccharides (LPS), and flagellin as pathogen-related molecular patterns (PAMPs), which, in combination with the pattern recognition receptors (PRRs) of host cells promotes the expression and secretion of inflammation-causing cytokines and activates innate immune responses such as inflammasomes. To identify useful compounds against H. pylori-associated gastric disorders, the effect of chalcone derivatives to activate the nucleotide-binding oligomerization domain (NOD)-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome was examined in an H. pylori-infected human monocytic THP-1 cell line in this study. Among the five synthetic structurally-related chalcone derivatives examined, 2'-hydroxy-4',6'-dimethoxychalcone (8) and 2'-hydroxy-3,4,5- trimethoxychalcone (12) strongly blocked the NLRP3 inflammasome in H. pylori-infected THP-1 cells. At 10 μM, these compounds inhibited the production of active IL-1β, IL-18, and caspase-1, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) oligomerization, but did not affect the expression levels of NLRP3, ASC, and pro-caspase-1. The interruption of NLRP3 inflammasome activation by these compounds was found to be mediated via the inhibition of the interleukin-1 receptor-associated kinase 4 (IRAK4)/IκBα/NF-κB signaling pathway. These compounds also inhibited caspase-4 production associated with non-canonical NLRP3 inflammasome activation. These results show for the first time that certain chalcones could interrupt the activation of the NLRP3 inflammasome in H. pylori-infected THP-1 cells. Therefore, these chalcones may be helpful in alleviating H. pylori-related inflammatory disorders including chronic gastritis.

Presence of cagPAI genes and characterization of vacA s, i and m regions in Helicobacter pylori isolated from Alaskans and their association with clinical pathologies

Introduction. Gastric cancer is a health disparity in the Alaska Native people. The incidence of Helicobacter pylori infection, a risk factor for non-cardia gastric adenocarcinoma, is also high. Gastric cancer is partially associated with the virulence of the infecting strain.Aim. To genotype the vacA s, m and i and cag pathogenicity island (cagPAI) genes in H. pylori from Alaskans and investigate associations with gastropathy.Methodology. We enrolled patients with gastritis, peptic ulcer disease (PUD) and intestinal metaplasia (IM) in 1998-2005 and patients with gastric cancer in 2011-2013. Gastric biopsies were collected and cultured and PCR was performed to detect the presence of the right and left ends of the cagPAI, the cagA, cagE, cagT and virD4 genes and to genotype the vacA s, m and i regions.Results. We recruited 263 people; 22 (8 %) had no/mild gastritis, 121 (46 %) had moderate gastritis, 40 (15%) had severe gastritis, 38 (14 %) had PUD, 30 (11 %) had IM and 12 (5 %) had gastric cancer. H. pylori isolates from 150 (57%) people had an intact cagPAI; those were associated with a more severe gastropathy (P≤0.02 for all comparisons). H. pylori isolates from 77 % of people had either the vacA s1/i1/m1 (40 %; 94/234) or s2/i2/m2 (37 %; 86/234) genotype. vacA s1/i1/m1 was associated with a more severe gastropathy (P≤0.03 for all comparisons).Conclusions. In this population with high rates of gastric cancer, we found that just over half of the H. pylori contained an intact cagPAI and 40 % had the vacA s1/i1/m1 genotype. Infection with these strains was associated with a more severe gastropathy.

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.

Detection of Helicobacter pylori and its virulence genes (cagA, dupA, and vacA) among patients with gastroduodenal diseases in Chris Hani Baragwanath Academic Hospital, South Africa

BACKGROUND

The global prevalence of H. pylori approaches 50%, with prevalence rates between 20 and 40% in developed countries and up to 90% in Africa and other developing nations of the world. Development of H. pylori-associated diseases is determined by a number of virulence factors. This study aimed at determining the prevalence of H. pylori infections and virulence genes (cagA, dupA, and vacA); the relationship between virulence factors and gastroduodenal diseases among patients.

METHODS

Gastric biopsies were obtained from patients and cultured, DNA was extracted from cultured isolates and biopsies for PCR assay after which samples were investigated using standard laboratory procedures. Data of associated risk factors were obtained with the aid of questionnaires.

RESULTS

Of the 444 participants, H. pylori was detected in 115 (25.9%) from culture analysis and 217 (48.9%) by direct PCR method. Ninety-eight (85.2%) of the culture-positive patients were also detected by PCR giving an overall prevalence of 52.7% (234/444). The highest number of H. pylori isolates 76.9% (180/234) was obtained from patients suffering from pangastritis. The CagA virulence gene was found in 62% (145/234), dupA in 53.4% (125/234) and vacA in 90.6% (212/234). VacA genotype s1 m1 was the most prevalent [56.4% (132)] followed by s2 m2 [11.5% (27)], s2 m1 [10.3% (24)] and [s1 m2 9.4% (22)]. There was a significant association observed in vacA s1 and peptic ulcer disease, as well as vacA s1/m2 and gastric erosion (P < 0.05).

CONCLUSION

The study revealed a significant association between virulence genes and the development of certain forms of gastric infections while the variations in H. pylori detection and the associated risk factors investigated in the study were not significantly related.

Genetic diversity and amino acid sequence polymorphism in Helicobacter pylori CagL hypervariable motif and its association with virulence markers and gastroduodenal diseases

Genetic variability in cagL gene especially within the Helicobacter pylori CagL hypervariable motif (CagLHM) may affect the development of gastric cancer. Therefore, this study was conducted to investigate the association of CagL diversity with clinical outcomes and with H pylori virulence markers. A total of 126 patients with different gastric diseases including non-ulcer dyspepsia (NUD), peptic ulcer disease (PUD), gastric erosion (GE), and gastric cancer (GC) were enrolled. H pylori was cultured from gastric biopsies, and the isolates were screened for the presence of cagL, cagA, vacA, babA2, sabA, and cagPAI integrity by PCR. The amino acid polymorphisms of cagL were analyzed using DNA sequencing. We isolated 61 (48.4%) H pylori strains from 36 NUD, eight PUD, 12 GE, and five GC patients. Almost all isolates were cagL positive (97%), and their RGD, RHS, and SKIIVK motifs were highly conserved. Among 10 CagLHM variants identified, NEIGQ and NKIGQ were detected as the most prevalent sequences. Interestingly, a significant association was found between the presence of NKMGK and PUD (P = 0.002). Notably, the NEIGQ isolates with multiple C-type EPIYA repeat that carried intact cagPAI correlated with disease risk for PUD, GE, and GC (P = 0.021). In conclusion, we identified novel variants of H pylori CagLHM sequences in Iranian population such as NKMGK, which was associated with disease risk for PUD. Further studies using a large number of strains are required to better clarify the function of certain CagLHM motifs in gastric carcinogenesis and disease outcome.

H. pylori-associated pathologic findings among Alaska native patients

Helicobacter pylori infection is common among Alaska native (AN) people, however scant gastric histopathologic data is available for this population. This study aimed to characterise gastric histopathology and H. pylori infection among AN people. We enrolled AN adults undergoing upper endoscopy. Gastric biopsy samples were evaluated for pathologic changes, the presence of H. pylori, and the presence of cag pathogenicity island-positive bacteria. Of 432 persons; two persons were diagnosed with gastric adenocarcinoma, two with MALT lymphoma, 40 (10%) with ulcers, and 51 (12%) with intestinal metaplasia. Fifty-five per cent of H. pylori-positive persons had cag pathogenicity island positive bacteria. The gastric antrum had the highest prevalence of acute and chronic moderate-severe gastritis. H. pylori-positive persons were 16 and four times more likely to have moderate-severe acute gastritis and chronic gastritis (p < 0.01), respectively. An intact cag pathogenicity island positive was correlated with moderate-severe acute antral gastritis (53% vs. 31%, p = 0.0003). H. pylori-positive persons were more likely to have moderate-severe acute and chronic gastritis compared to H. pylori-negative persons. Gastritis and intestinal metaplasia were most frequently found in the gastric antrum. Intact cag pathogenicity island positive was correlated with acute antral gastritis and intestinal metaplasia.

Helicobacter pylori infection downregulates duodenal CFTR and SLC26A6 expressions through TGFβ signaling pathway

BACKGROUND

The pathogenesis of Helicobacter pylori (H. pylori) infection-induced duodenal ulcer remains to be elucidated. Duodenal mucosal bicarbonate secretion is the most important protective factor against acid-induced mucosal injury. We previously revealed that H. pylori infection downregulated the expression and functional activity of duodenal mucosal cystic fibrosis transmembrane conductance regulator (CFTR) and solute linked carrier 26 gene family A6 (SLC26A6) which are the two key duodenal mucosal epithelial cellular bicarbonate transporters to mediate duodenal bicarbonate secretion. In this study, we investigated the mechanism of H. pylori infection-induced duodenal CFTR and SLC26A6 expression downregulation.

RESULTS

We found that H. pylori infection induced the increase of serum transforming growth factor β (TGFβ) level and duodenal mucosal TGFβ expression and the decrease of duodenal mucosal CFTR and SLC26A6 expressions in C57 BL/6 mice. The results from the experiments of human duodenal epithelial cells (SCBN) showed that H. pylori increased TGFβ production and decreased CFTR and SLC26A6 expressions in SCBN cells. TGFβ inhibitor SB431542 reversed the H. pylori-induced CFTR and SLC26A6 expression decreases. The further results showed that TGFβ directly decreased CFTR and SLC26A6 expressions in SCBN cells. TGFβ induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and P38 MAPK inhibitor SB203580 reversed the TGFβ-induced CFTR and SLC26A6 expression decreases.

CONCLUSIONS

H. pylori infection downregulates duodenal epithelial cellular CFTR and SLC26A6 expressions through TGFβ-mediated P38 MAPK signaling pathway, which contributes to further elucidating the pathogenesis of H. pylori-associated duodenal ulcer.

Gastric cancer in Alaska Native people: A cancer health disparity

AIM

To evaluate recent trends in gastric cancer incidence, response to treatment, and overall survival among Alaska Native (AN) people.

METHODS

A retrospective analysis of the Alaska Native Medical Center patient database was performed. Patient history, clinical, pathological, response to treatment and patient outcomes were collected from one-hundred and thirty-two AN gastric cancer patients. The Surveillance, Epidemiology and End Result database 18 was used to collect comparison United States non-Hispanic White (NHW) and AN gastric cancer patient data between 2006-2014.

RESULTS

AN gastric cancer patients have a higher incidence rate, a poorer overall survival, and are diagnosed at a significantly younger age compared to NHW patients. AN patients differ from NHW patients in greater prevalence of non-cardia, diffuse subtype, and signet ring cell carcinomas. AN females were more likely to be diagnosed with later stage cancer, stage IV, compared to AN males. Diminished overall survival was observed among AN patients with increasing stage, O+ blood type, < 15 lymph nodes examined at resection, and no treatment. This study is the first report detailing the clinicopathologic features of gastric cancer in AN people with outcome data.

CONCLUSION

Our findings confirm the importance of early detection, treatment, and surgical resection for optimizing AN patient outcomes. Further research on early detection markers are warranted.

Prevalence of Helicobacter pylori cagA and iceA Genes and Their Association with Gastrointestinal Diseases

H. pylori infection causes peptic ulcer, chronic gastritis, mucosa-associated lymphoid tissue lymphoma, and gastric carcinoma. It has several virulence factors such as cytotoxin-associated gene A(cagA) and the induced by contact with epithelium antigen (iceA). We aimed to explore the relationship between cagA and iceA of H. pylori and gastrointestinal diseases. One hundred and eighteen patients who attended Gastrointestinal Endoscopy Unit at Zagazig University Hospitals, Egypt, were included in this study. Two gastric biopsies were collected and evaluated by rapid urease test (RUT) and PCR. cagA and iceA genes were amplified by PCR. We found that 54 patients (45.76%) were positive by both RUT and PCR. cagA and iceA genes were present in 57.4% and 46.29% of the studied patients, respectively. cagA was the most prevalent gene in gastritis (33.3%) and peptic ulcer (68.7%). iceA1/iceA2 positive genes were the most prevalent in gastric cancer (75%). iceA1 gene was present in 38.7% of cagA positive cases, but iceA2 gene was present in 45.2% of cagA positive cases. iceA1/iceA2 positive genes were present in 29% of cagA positive cases. In conclusion, cagA and iceA genes could be used as markers for severe gastrointestinal diseases. iceA gene was strongly related to cagA gene.

The Evaluation of Diagnostic and Predictive Values of Helicobacter pylori Stool Antigen Test in Iranian Patients with Dyspepsia

BACKGROUND AND OBJECTIVES

Iran, as a developing country, is experiencing high burdens of Helicobacter pylori (Hp)-associated non-communicable diseases. Hp stool antigen test (HpSA) is widely used as an inexpensive and feasible noninvasive method to diagnose Hp infection, instead of invasive approaches. The current study aimed at evaluating the diagnostic and predictive values of HpSA test for Hp infection in Iranian patients with dyspepsia.

METHODS

The current cross sectional study was performed on 100 patients with dyspepsia. Gastric mucosal specimens were taken, processed, and examined according to the standard protocols. Simultaneously, stool samples were obtained and sent to laboratory for further analyses. Hp stool antigen titers were assessed using enzyme-linked immunosorbent assay (ELISA) technique.

RESULTS

Stool antigen titers were not associated with gender (P-value=0.284), but correlated to age (r=0.213, P-value=0.034). Considering 0.385 as a cutoff point, the HpSA test had 80.4% sensitivity and 85.7% specificity.

CONCLUSION

Based on cost-effectiveness of HpSA test, the current study findings corroborated the use of HpSA test to detect and follow-up patients with Hp infection, as an alternative method to detect Hp rather than invasive procedures.

Helicobacter pylori cagA and vacA genes in dyspeptic Ghanaian patients

BACKGROUND

Helicobacter pylori infection is prevalent in Ghana. The development of gastro-duodenal disease is dependent on virulence of the infecting strain, host susceptibility and environmental factors. Helicobacter pylori cagA and vacA strains induce more inflammation, ulceration and oncogenesis. Here, for the first time we present data on H. pylori cagA and vacA genes and their association with gastro-duodenal disease in Ghana. A total of 159 patients with dyspepsia at Korle-Bu Teaching Hospital, Accra, were investigated for H. pylori with urease-CLO, of which 113 (71.1%) were positive. Genomic DNA was extracted from antral biopsies using QIAGEN DNeasy kit. Detection of H. pylori vacA and cagA genes were determined by PCR as previously described.

RESULTS

In total, 110 (69.2%) vacAs1, 71 (44.7%) vacAm1, 35 (22.0%) vacAm2, 77 (48.4%) cagA-(hydrophilic region) and 109 (68.6%) cagA-(internal duplication region) were detected. In multivariate analysis, duodenal ulcer was more likely than other diagnoses to have detectable cagA-(hydrophilic region) (OR 3.1 CI 1.2-7.9) or vacAs1m1 (OR 6.5 CI 1.2-34.0).

CONCLUSIONS

Majority of biopsies were colonized with H. pylori harboring both cagA and vacA. H. pylori cagA-(internal duplication region) was more prevalent than cagA-(hydrophilic region). Duodenal ulcer was more likely than other diagnoses to have detectable cagA-(hydrophilic region) or vacAs1m1.

Helicobacter pylori vacA s1m1 genotype but not cagA or babA2 increase the risk of ulcer and gastric cancer in patients from Southern Mexico

BACKGROUND

The vacA, cagA and babA2 genotypes of Helicobacter pylori are associated with gastric pathology. The objectives were to determine the frequency of infection and distribution of the vacA, cagA and babA2 genotypes of H. pylori in patients with gastric ulcer, chronic gastritis and gastric cancer, and to evaluate the association of virulent genotypes with diagnosis.

METHODS

We studied 921 patients with symptoms of dyspepsia or with presumptive diagnosis of gastric cancer. The DNA of H. pylori and the vacA, cagA and babA2 genes was detected by PCR in total DNA from gastric biopsies. The association of H. pylori and of its cagA, vacA and babA2 genotypes with diagnosis was determined by calculating the odds ratio (OR).

RESULTS

Chronic gastritis was confirmed in 767 patients, gastric ulcer in 115 and cancer in 39. The prevalence of H. pylori was 47.8, 49.6 and 61.5% in those groups, respectively. H. pylori was more frequent in the surrounding tissue (69.2%) than in the tumor (53.8%). The vacA s1m1 genotype predominated in the three groups (45.2, 61.4 and 83.3%, respectively). H. pylori was associated with cancer (OR_adjusted = 2.08; 95% CI 1.05-4.13; p = 0.035) but not with ulcer (OR_adjusted = 1.07; 95% CI 0.71-1.61; p = 0.728). The s1m1 genotype was associated with ulcer and cancer (OR_adjusted = 2.02; 95% CI 1.12-3.62; p = 0.019 and OR_adjusted = 6.58; 95% CI 2.15-20.08; p = 0.001, respectively). babA2 was associated with gastric cancer, and cagA was not associated with the diagnosis.

CONCLUSIONS

In population from Southern Mexico, H. pylori and the s1m1 genotype were associated with gastric cancer and the s1m1/cagA+/babA2+ strains predominated in tumor and adjacent tissue.

Helicobacter pylori cag Pathogenicity Island cagL and orf17 Genotypes Predict Risk of Peptic Ulcerations but not Gastric Cancer in Iran

BACKGROUND

Gastric cancer (GC) is the third most common cancer regarding mortality in the world. The cag pathogenicity island (PAI) of Helicobacter pylori which contains genes associated with a more aggressive phenotype may involve in the pathogenesis of gastrointestinal disease. We here aimed to examine the associations of cagH, cagL, orf17, and cagG genotypes of H. pylori cag PAI with severe gastrointestinal disease.

MATERIALS AND METHODS

A total of 242 H. pylori strains were genotyped. Histopathological examination and classification of subjects were performed.

RESULTS

The frequencies of the cagH, cagL, cagG, and orf17 genotypes were 40/54 (74.1%), 53/54 (98.1%), 38/54 (70.4%), and 43/54 (79.6%), respectively, in patients with peptidic ulceration (PU),while in the control group, the frequencies were 87/147 (59.6%) for cagH, 121/146 (82.9%) for cagL, 109/146 (74.7%) for cagG, and 89/146 (61.0%) for orf17. The results of simple logistic regression analysis showed that the cagL and orf17 genotypes were significantly associated with an increased risk of PU not GC; the ORs (95% CI) were 10.950 (1.446-82.935), and 2.504 (1.193-5.253), respectively. No significant association was found between the cagH and cagG genotypes and the risk of both the PU and the GC in Iran (P>0.05). Finally, multiple logistic regression analysis showed that the cagL genotype was independently and significantly associated with the age- and sex-adjusted risk for PU; the OR (95% CI) was 9.557 (1.219-17.185).

CONCLUSIONS

We conclude that the orf17 and especially cagL genotypes of H. pylori cag PAI could be factors for risk prediction of PU, but not GC in Iran.

Study of the clinical relevance of Helicobacter pylori virulence genes to gastric diseases among Egyptian patients

BACKGROUND AND STUDY AIMS

Helicobacter pylori infection is common in Egypt. It has been associated with gastritis, ulcers and it is a risk factor for gastric cancer. We aimed to study the correlation between the presence of H. pylori virulence factors and the histopathological and endoscopic findings in gastric biopsies.

PATIENTS AND METHODS

Gastric biopsies from thirty seven patients scheduled for diagnostic endoscopy in Cairo University hospital were included in the study. All gastric biopsies were subjected to histopathological examination and PCR assay for detection of 16S rRNA gene to diagnose H. pylori infection, detection of H. pylori virulence factors by PCR for cagA and vacA genotypes and serological analysis of H. pylori (cagA, vacA, P25, and P19) IgG antibodies by immunoblot assay were done.

RESULTS

H. pylori infection was detected in 23 (62.2%) cases by histopathology while 28/37 (75.7%) were positive for H. pylori 16S rRNA gene by PCR. By PCR seventeen samples out of 37 (45.9%) were positive for cagA gene and five (13.5%) for cag empty site gene.

CONCLUSION

The most common vacA genotype identified was vacA s2m2 genotype in 10 (27.02%). No statistical correlation was found between IgG antibodies against different antigens of H. pylori virulence factors (cagA, vacA, p25, and p19) and the degree of gastritis except for IgG antibodies against the UreA antigen.

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.

High Frequency of vacA s1m2 Genotypes Among Helicobacter pylori Isolates From Patients With Gastroduodenal Disorders in Kermanshah, Iran

Background:

Helicobacter pylori infection and related diseases outcome are mediated by a complex interplay between bacterial, host and environmental factors. Several distinct virulence factors of H. pylori have been shown to be associated with different clinical outcomes. Here we focused on vacA and cagA genotypes of H. pylori strains isolated from patients with gastric disorder.

Objectives:

The aim of this study was to determine the frequency of two toxins and genotypes of VacA toxin in patients referred to a central hospital in the west of Iran (Imam Reza hospital, Kermanshah) during 2011 - 2012.

Patients and Methods:

Samples were collected from patients infected with H. pylori. Gastric biopsy specimens from the stomach antrum and corpus were cultured. PCR analysis was performed for genotyping H. pylorivacA and cagA genes.

Results:

Helicobacter pylori was isolated from 48% (96/200) of patients with gastroduodenal disorders. In 81/96 (84%) cases, the cagA gene was present. Among different genotypes of vacA, two s1m2 and s2m2 genotypes were dominant with frequency of 39.5% and 50%, respectively. The frequency of the s1m1 genotype was 7.2% (7/96), which is much lower than elsewhere. H. pylori isolates with positive results for cagA gene and vacA s1m2 genotypes showed statistically significant correlation with peptic ulcer (s1m2 13/34 [38.2%] P = 0.003). However, isolates of H. pylori infection with cagA gene and vacAs2m2 genotypes were significantly associated with development of gastritis (s2m2 41/42 [97.6%] P = 0.000).

Conclusions:

About 90% of H. pylori strains potentially contained vacAs2m2 and s1m2 genotypes. Infection with H. pylori strain containing the cagA gene or the vacAs1m1 and s1m2 genotypes was associated with increased incidence of peptic ulcer disease (PUD).

Reciprocal impact of host factors and Helicobacter pylori genotypes on gastric diseases

AIM: To assess the impact of Helicobacter pylori (H. pylori) genotypes and patient age and sex on the development of gastric diseases.

METHODS: H. pylori-infected patients (n = 233) referred to the endoscopy unit at Tehran University of Medical Sciences (Tehran, Iran) were diagnosed with chronic gastritis (CG), gastric ulcer (GU), or duodenal ulcer (DU). Brucella blood agar was used for biopsy cultures and H. pylori isolation under microaerobic conditions. H. pylori isolates were confirmed with biochemical tests and through amplification of the 16S rRNA gene. DNA was extracted from fresh cultures of the H. pylori isolates and used for amplification of vacA alleles and the cagA gene. Statistical analysis was performed to determine the association between H. pylori genotypes, age (< 40 years vs > 40 years) and sex of the patient, and gastric diseases.

RESULTS: CG was the most prevalent gastric disease (113/233; 48.5%), compared to GU (64/233; 27.5%) and DU (56/233; 24%). More patients were male, and gastric diseases were more frequent in patients > 40 years (P < 0.05). The percentage of CG and GU patients that were male and female did not show a significant difference; however DU was more common in males (P < 0.05). Interestingly, a diagnosis of CG in patients > 40 years was more common in females (18.5%) than males (11.6%) (P = 0.05), whereas a diagnosis of GU or DU in patients > 40 years was more frequent in males (14.6% vs 10.7% and 12.4% vs 4.3%, respectively). Overall, genotyping of the H. pylori isolates revealed that the vacA s1 (82%), vacA m2 (70%), and cagA⁺ (72.5%) alleles were more frequent than vacA s2 (18%), vacA m1 (29.2%), and cagA^- (all P < 0.05). The vacA s1m2cagA⁺ genotype was the most prevalent within the three disease groups. vacA s1m2 frequency was 56.2% with a similar occurrence in all diagnoses, while vacA s1m1 appeared more often in DU patients (33.9%). A genotype of vacA s2m2 occurred in 15% of isolates and was more common in CG patients (21.2%); vacA s2m1 was the least common genotype (3%). The vacA s1 allele was found to be a risk factor for DU, vacA s2 for CG, and vacA s1 and vacA s2 for GU (all P < 0.05). The vacA s2m2 genotype was associated with the development of CG and GU compared to DU (P < 0.05). No correlation was found between vacA m or cagA and gastric diseases.

CONCLUSION: The outcome of H. pylori infection is the result of interaction between bacterial genotypes and the age and sex of infected individuals.

Evaluation of the Atlas Helicobacter pylori stool antigen test for diagnosis of infection in adult patients

BACKGROUND

Helicobacter pylori (H. pylori) is one of the most important causes of dyspepsia and gastric cancer and diagnosis can be made by invasive or non-invasive methods. The Atlas Helicobacter pylori antigen test is a new rapid non-invasive method which is simple to conduct. The aim of this study was to determine its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy.

MATERIALS AND METHODS

This prospective study was conducted between July 2012 and December 2013. Stool samples of 59 dyspeptic patients who underwent upper endoscopy were evaluated for H. pylori stool antigen.

RESULTS

From the 59 patients who participated in this study, there were 36 (61%) males and 23 (39%) females. H. pylori was diagnosed in 24 (40.7%) gastric biopsies, 22 (91.7 %) of these being positive for the Atlas H. pylori antigen test. The sensitivity, specificity, PPV, NPV and accuracy were 91.7%, 100%, 100%, 94.6% and 96.6% respectively.

CONCLUSIONS

The Atlas H. pylori antigen test is a new non-invasive method which is simple to perform and avails reliable results in a few minutes. Thus it can be the best option for the diagnosis of H. pylori infection due to its high sensitivity and specificity.

Prevalence of Helicobacter pylori vacA, cagA, and iceA Genotypes in Cuban Patients with Upper Gastrointestinal Diseases

Virulence factors of Helicobacter pylori can predict the development of different gastroduodenal diseases. There are scarce reports in Cuba about H. pylori isolates genotyping. The aim of the present investigation was to identify allelic variation of the virulence genes vacA, cagA, and iceA in sixty-eight patients diagnosed as H. pylori positive by culture. In seven out of 68 patients, strains from both gastric regions were obtained and considered independent. DNA was extracted from all the H. pylori strains and evaluated by PCR-genotyping. The vacA s1 allele, cagA gene, and iceA2 allele were the most prevalent (72.0%, 56.0%, and 57.3%, respectively). Alleles from m-region showed a similar frequency as s1a and s1b subtypes. The presence of multiple H. pylori genotypes in a single biopsy and two gastric region specimens were found. Significant statistical association was observed between iceA2 allele and patients with non-peptic ulcer dyspepsia (NUD) (P = 0.037) as well as virulence genotypes (s1, s1m2) and patients over 40 years old (P < 0.05). In conclusion, the results demonstrated a high prevalence of H. pylori virulent genotypes in Cuban patients over 40 years old while iceA2 alleles demonstrated a good specificity in patients with NUD.

Correlation of Helicobacter pylori genotypes with gastric histopathology in the central region of a South-European country

BACKGROUND

Outcome of Helicobacter pylori (H. pylori) infection results from interaction of multiple variables including host, environmental and bacterial-associated virulence factors.

AIM

This study aimed to investigate the correlation of cagA, cagE, vacA, iceA and babA2 genotypes with gastric histopathology and disease phenotype in the central region of a South-European country.

METHODS

This prospective study involved 148 infected patients (110 female; mean age 43.5 ± 13.4 years) submitted to endoscopy with corpus and antrum biopsies. H. pylori was cultured and DNA extracted from the isolates. Genotypes were determined by PCR. Histopathological features were graded according to the updated Sydney system and OLGA/OLGIM classification. Only patients with single H. pylori genotypes and complete histopathological results were included.

RESULTS

Antrum samples presented higher degrees of atrophy, intestinal metaplasia, chronic inflammation and neutrophil activity. Genotype distribution was as follows: cagA-31.8 %; cagE-45.9 %; vacA s1a-24.3 %; vacA s1b-19.6 %; vacA s1c-0.7 %; vacA s2-55.4 %; vacA m1-20.9 %; vacA m2-79.1 %; vacA s1m1-18.9 %; vacA s1m2-25.7 %; vacA s2m1-2 %; vacA s2m2-53.4 %; iceA1-33.8 %; iceA2-66.2 %; babA2-12.2 %. CagA genotype was significantly associated with higher degrees of intestinal metaplasia, neutrophil activity, chronic inflammation and OLGIM stages. BabA2 was linked with higher H. pylori density. Strains with vacA s1m1 or vacA s1m1 + cagA positive genotypes had a significant association with peptic ulcer and vacA s2m2 with iron-deficient anemia.

CONCLUSIONS

cagA, vacA s1m1 and babA2 genotypes are relatively rare in the central region of Portugal. cagA-positive strains are correlated with more severe histopathological modifications. This gene is commonly associated with vacA s1m1, and such isolates are frequently found in patients with peptic ulcer.

Clinical relevance of cagL gene and virulence genotypes with disease outcomes in a Helicobacter pylori infected population from Iran

Helicobacter pylori infection is common in Iran as in other developing countries. Certain genotypes of H. pylori have been associated with increased occurrence of chronic gastritis, peptic ulcers, and gastric adenocarcinoma. The aim of this study was to investigate the clinical relevance of cagL gene and other virulence genotypes of H. pylori isolates with clinical outcomes in Iranian patients. Totally, 126 symptomatic patients who underwent gastroduodenal endoscopy were enrolled in the study. Sixty-one H. pylori strains were isolated from the patients studied. The presence of the cagL, cagA, vacA, iceA, babA2 and sabA genes in the corresponding H. pylori isolates were determined by polymerase chain reaction and the results were compared with clinical outcomes and histopathology. The cagL, cagA, vacA s1, vacA s2, vacA m1, vacA m2, iceA1, iceA2, babA 2 , and sabA genotypes were detected in 96.7, 85.2, 75.4, 24.6, 29.5, 70.5, 42.6, 23, 96.7, and 83.6% of the isolates, respectively. The three genotypic combinations, cagL/cagA/vacAs1m1/iceA1/babA2/sabA, cagL/cagA/vacAs1m2/iceA1/babA2/sabA, and cagL/cagA/vacAs1m2/iceA2/babA2/sabA were determined as the most prevalent combined genotypes. There was a significant correlation between the presence of cagL gene and cagA positivity (P = 0.02). No significant correlation was found between the various genotypes and clinical outcomes (P > 0.05). The present study showed a very high prevalence of cagL genotype among the H. pylori isolates from Iranian patients. Our results demonstrated that neither single genotype nor combination genotypes of virulence-associated genes was significantly helpful markers for predicting the severity of gastroduodenal disease associated with H. pylori infection in Iranian patients.

Five-year monitoring of considerable changes in tyrosine phosphorylation motifs of the Helicobacter pylori cagA gene in Iran

CagA is a major virulence factor of Helicobacter pylori involved in host cell modulation. The C-terminal part of CagA containing the EPIYA motifs is highly variable and is important for the biological activity of the protein. The aim of this study was consideration of the changes in cagA tyrosine phosphorylation motifs (TPMs) of H. pylori. A set of 302 H. pylori DNA samples from the Iranian population from 2006 to 2011 was selected for the proposed study. The cagA gene and its TPMs were assessed by using polymerase chain reaction (PCR) and specific primers. The prevalence of the cagA gene in our study ranged from 91.43% to 97.06% (with an average of 95.03%). Out of the cagA-positive samples, the prevalence of TPMs A and B increased from 12.5% and 23.44% to 71.2% and 63.63%, respectively. Also, the prevalence of samples infected with Western and East Asian types of H. pylori ranged from 64.06% to 5.73% for the Western type and 17.19% to 51.59% for the East Asian type. Overall, our results showed a high prevalence of the cagA gene. Also, it seems that cagA TPMs of H. pylori is undergoing a change from the Western type to the East Asian type in Iran.

Study of Helicobacter pylori genotype status in cows, sheep, goats and human beings

Background

Helicobacter pylori is one of the most controversial bacteria in the world causing diverse gastrointestinal diseases. The transmission way of this bacterium still remains unknown. The possibility of zoonotic transmission of H. pylori has been suggested, but is not proven in nonprimate reservoirs. In the current survey, we investigate the presence of H. pylori in cow, sheep and goat stomach, determine the bacterium virulence factors and finally compare the human H. pylori virulence factors and animals in order to examine whether H. pylori might be transmitted from these animals to human beings.

Methods

This cross- sectional study was performed on 800 gastric biopsy specimens of cows, sheep, goats and human beings. The PCR assays was performed to detection of H. pylori, vacA and cagA genes. The PCR products of Ruminant’s samples with positive H. pylori were subjected to DNA sequencing analysis. Statistical tests were applied for data analysis.

Results

Overall 6 (3%) cows, 32 (16%) sheep and 164 (82%) human beings specimens were confirmed to be H. pylori positive; however we were not able to detect this bacterium in all 200 goat samples. The vacA s1a/m1a was the predominant H. pylori genotype in all three kinds of studied population. There was 3.4–8.4% variability and 92.9-98.5% homology between sheep and human samples.

Conclusions

Considering the high sequence homology among DNA of H. pylori isolated from sheep and human, our data suggest that sheep may act as a reservoir for H. pylori and in the some extent share the ancestral host for the bacteria with human.

A novel association between cytotoxin-associated gene A (CagA) positive strain of Helicobacter pylori and unexplained recurrent early pregnancy loss

OBJECTIVE

To assess whether or not there is an association between the cytotoxin-associated gene A (CagA)-positive strain of Helicobacter (H.) pylori and unexplained recurrent early pregnancy loss (REPL).

METHODS

A case control study was conducted in a tertiary care maternity centre during a one-year period. Ninety-six women with first trimester unexplained REPL admitted for surgical or medical termination of pregnancy were included in the study group (group 1), along with 96 women who suffered a first trimester missed abortion but had no history of REPL and who were included in the control group (group 2). Sera from all these women were collected for detection of the CagA line of IgG type of H. pylori using an immunoblotting assay. The main outcome measure was the association between the CagA-positive strain of H. pylori and unexplained REPL.

RESULTS

A significantly greater proportion of women were seropositive for the CagA- H. pylori strain in group 1 than in group 2 (71 [74%] vs. 51 [53%], respectively; p = 0.003).

CONCLUSION

The CagA-positive strain of H. pylori seems to be significantly more prevalent among women with unexplained REPL when compared to women with a single missed abortion.

Advances in understanding the relationship between the Helicobacter pylori CagA gene and diseases of the digestive system

The relationship between the pathogenicity and virulence genes of Helicobacter pylori (H. pylori) has become a hot topic in research of digestive system diseases in recent years. Studies have shown that H. pylori is closely associated with the development of reflux esophagitis, functional dyspepsia, chronic gastritis, peptic ulcer, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, gastric cancer and liver diseases. The H. pylori CagA gene plays an important role in the development of these diseases. This paper reviews recent progress in understanding the relationship between the CagA gene and digestive system diseases.

Genotyping of Helicobacter pylori virulence-associated genes shows high diversity of strains infecting patients in western Venezuela

BACKGROUND

Helicobacter pylori is a major cause of chronic gastritis and an established risk factor for gastric adenocarcinoma. This bacterium also exhibits an extraordinarily high genetic diversity.

METHODS

The genetic diversity of H. pylori strains from Venezuelan patients with chronic gastritis was evaluated by PCR-typing of vacA, cagA, iceA, and babA2 virulence-associated genes using DNA extracted directly from biopsies. The nucleotide sequence and prevalence of size variants of iceA1, iceA2, and babA2 PCR products were introduced in this analysis.

RESULTS

The frequency of vacA s1 was associated (p<0.01) with moderate/severe grades of atrophic gastritis. The cagA, iceA1, iceA2, and babA2 genotypes were found in 70.6%, 66.4%, 33.6%, and 92.3% of strains, respectively. The frequency of iceA2 and its subtype iceA2_D were higher (p<0.015) in cases with moderate/severe granulocytic inflammation. The most prevalent combined genotypes were vacA s1m1/cagA/iceA1/babA2 (26.3%), vacA s2m2/iceA1/babA2 (19.5%), and vacA s1m1/cagA/iceA2/babA2 (18.8%). Sequence analysis of iceA1, iceA2, and babA2 PCR-amplified fragments allowed us to define allelic variants and to increase the number of genotypes detected (from 19 to 62). A phylogenetic tree made with iceA1 sequences showed that the H. pylori strains analyzed here were grouped with those of Western origin.

CONCLUSIONS

Our results show that patients from the western region of Venezuela have an elevated prevalence of infection with H. pylori strains carrying known virulence genotypes with high genetic diversity. This highlights the importance of identifying gene variants for an early detection of virulent genotypes.

Polymorphism in the Helicobacter pylori CagA and VacA toxins and disease

Half of the world's population is infected with Helicobacter pylori and approximately 20% of infected individuals develop overt clinical disease such as ulcers and stomach cancer. Paradoxically, despite its classification as a class I carcinogen, H. pylori has been shown to be protective against development of asthma, allergy, and esophageal disease. Given these conflicting roles for H. pylori, researchers are attempting to define the environmental, host, and pathogen interactions that ultimately result in severe disease in some individuals. From the bacterial perspective, the toxins, CagA and VacA, have each been shown to be polymorphic and to contribute to disease in an allele-dependent manner. Based on the notable advances that have recently been made in the CagA field, herein we review recent studies that have begun to shed light on the role of CagA polymorphism in H. pylori disease. Moreover, we discuss the potential interaction of CagA and VacA as a mediator of gastric disease.

Ethnicity association of Helicobacter pylori virulence genotype and metronidazole susceptibility

AIM: To characterise the cag pathogenicity island in Helicobacter pylori (H. pylori) isolates by analysing the strains’vacA alleles and metronidazole susceptibilities in light of patient ethnicity and clinical outcome.

METHODS: Ninety-five H. pylori clinical isolates obtained from patients with dyspepsia living in Malaysia were analysed in this study. Six genes in the cagPAI region (cagE, cagM, cagT, cag13, cag10 and cag67) and vacA alleles of the H. pylori isolates were identified by polymerase chain reaction. The isolates’ metronidazole susceptibility was also determined using the E-test method, and the resistant gene was characterised by sequencing.

RESULTS: More than 90% of the tested isolates had at least one gene in the cagPAI region, and cag67 was predominantly detected in the strains isolated from the Chinese patients, compared with the Malay and Indian patients (P < 0.0001). The majority of the isolates (88%) exhibited partial deletion (rearrangement) in the cagPAI region, with nineteen different patterns observed. Strains with intact or deleted cagPAI regions were detected in 3.2% and 8.4% of isolates, respectively. The prevalence of vacA s1m1 was significantly higher in the Malay and Indian isolates, whereas the isolates from the Chinese patients were predominantly genotyped as vacA s1m2 (P = 0.018). Additionally, the isolates from the Chinese patients were more sensitive to metronidazole than the isolates from the Malay and Indian patients (P = 0.047). Although we attempted to relate the cagPAI genotypes, vacA alleles and metronidazole susceptibilities to disease outcome, no association was observed. The vacA alleles were distributed evenly among the strains with intact, partially deleted or deleted cagPAI regions. Interestingly, the strains exhibiting an intact cagPAI region were sensitive to metronidazole, whereas the strains with a deleted cagPAI were more resistant.

CONCLUSION: Successful colonisation by different H. pylori genotypes is dependent on the host’s genetic makeup and may play an important role in the clinical outcome.

Prevalence of Helicobacter pylori vacA, cagA and iceA genotypes and correlation with clinical outcome

The aim of this study was to assess the genetic status of cagA, vacA subtype and iceA genotypes of Helicobacter pylori and the relationship with upper gastrointestinal diseases in Northeast China. Gastric biopsies were obtained from 378 patients with upper gastrointestinal diseases and 197 samples were used. The cagA, vacA alleles and iceA genotypes were determined by polymerase chain reaction. CagA was present in 176 (89.3%) of 197 patients. Of the 197 cases, 186 (94.4%) had vacA signal sequence s1c allele, 6 (3%) had s1a and 5 (2.5%) had s1b. The vacA s2 genotype was not detected in our study. VacA middle region sequences, m1 and m2, were found in 20 (10.2%) and 150 (76.1%), respectively. The allelic variant iceA1 (70.1%) was more prevalent than iceA2 (23.4%). The vacA allele s1am2 had a significant relationship with the presence of gastric cancer (p<0.05) and the iceA1 genotype was also associated with gastric cancer (p<0.05). These may be useful risk factors for upper gastrointestinal diseases.

Association between cagA and vacA genotypes and pathogenesis in a Helicobacter pylori infected population from South-eastern Sweden

Background

Chronic gastritis, peptic ulcer disease, and gastric cancer have been shown to be related to infection with Helicobacter pylori (H. pylori). Two major virulence factors of H. pylori, CagA and VacA, have been associated with these sequelae of the infection. In this study, total DNA was isolated from gastric biopsy specimens to assess the cagA and vacA genotypes.

Results

Variations in H. pylori cagA EPIYA motifs and the mosaic structure of vacA s/m/i/d regions were analysed in 155 H. pylori-positive gastric biopsies from 71 individuals using PCR and sequencing. Analysis of a possible association between cagA and vacA genotypes and gastroduodenal pathogenesis was made by logistic regression analysis. We found that H. pylori strains with variation in the number of cagA EPIYA motif variants present in the same biopsy correlated with peptic ulcer, while occurrence of two or more EPIYA-C motifs was associated with atrophy in the gastric mucosa. No statistically significant relation between vacA genotypes and gastroduodenal pathogenesis was observed.

Conclusions

The results of this study indicate that cagA genotypes may be important determinants in the development of gastroduodenal sequelae of H. pylori infection. In contrast to other studies, vacA genotypes were not related to disease progression or outcome. In order to fully understand the relations between cagA, vacA and gastroduodenal pathogenesis, the mechanisms by which CagA and VacA act and interact need to be further investigated.

Mixed infection with cagA positive and cagA negative strains of Helicobacter pylori lowers disease burden in The Gambia

Background

The prevalence of Helicobacter pylori including strains with putatively virulent genotypes is high, whereas the H. pylori-associated disease burden is low, in Africa compared to developed countries. In this study, we investigated the prevalence of virulence-related H. pylori genotypes and their association with gastroduodenal diseases in The Gambia.

Methods and Findings

DNA extracted from biopsies and H. pylori cultures from 169 subjects with abdominal pain, dyspepsia or other gastroduodenal diseases were tested by PCR for H. pylori. The H. pylori positive samples were further tested for the cagA oncogene and vacA toxin gene.

One hundred and twenty one subjects (71.6%) were H. pylori positive. The cagA gene and more toxigenic s1 and m1 alleles of the vacA gene were found in 61.2%, 76.9% and 45.5% respectively of Gambian patients harbouring H. pylori. There was a high prevalence of cagA positive strains in patients with overt gastric diseases than those with non-ulcerative dyspepsia (NUD) (p = 0.05); however, mixed infection by cagA positive and cagA negative strains was more common in patients with NUD compared to patients with gastric disease (24.5% versus 0%; p = 0.002).

Conclusion

This study shows that the prevalence of H. pylori is high in dyspeptic patients in The Gambia and that many strains are of the putatively more virulent cagA⁺, vacAs1 and vacAm1 genotypes. This study has also shown significantly lower disease burden in Gambians infected with a mixture of cag-positive and cag-negative strains, relative to those containing only cag-positive or only cag-negative strains, which suggests that harbouring both cag-positive and cag-negative strains is protective.