Helicobacter pylori phenotypes associated with peptic ulceration

Biofilm of Helicobacter pylori: Life Cycle, Features, and Treatment Options

Helicobacter pylori is a gastric pathogen that infects nearly half of the global population and is recognized as a group 1 carcinogen by the Word Health Organization. The global rise in antibiotic resistance has increased clinical challenges in treating H. pylori infections. Biofilm growth has been proposed to contribute to H. pylori's chronic colonization of the host stomach, treatment failures, and the eventual development of gastric diseases. Several components of H. pylori have been identified to promote biofilm growth, and several of these may also facilitate antibiotic tolerance, including the extracellular matrix, outer membrane proteins, shifted morphology, modulated metabolism, efflux pumps, and virulence factors. Recent developments in therapeutic approaches targeting H. pylori biofilm have shown that synthetic compounds, such as small molecule drugs and plant-derived compounds, are effective at eradicating H. pylori biofilms. These combined topics highlight the necessity for biofilm-based research in H. pylori, to improve current H. pylori-targeted therapeutic approaches and alleviate relative public health burden. In this review we discuss recent discoveries that have decoded the life cycle of H. pylori biofilms and current biofilm-targeted treatment strategies.

IgG subclasses against Helicobacter pylori isolates: an important tool for disease characterization

Helicobacter pylori infects around 50% of the world's population and is associated with diverse pathologies. In the most severe cases, the bacterium causes peptic ulcers and gastric cancer. The interplay between H. pylori and the host's immune response may help to determine the specific outcome of the infection. To study the relationship between antibody subclasses and variation in immune recognition, we determined the immunoglobulin G1 and 2 (IgG1 and IgG2) titres of sera obtained from patients with different H. pylori-associated pathologies. IgG1 and IgG2 titres were determined by ELISA in 44 sera of patients with different H. pylori-associated diseases (peptic ulcer, bleeding peptic ulcers, gastric cancer and dyspepsia). Soluble proteins from lysates were obtained from 12 different clinical isolates from similar associated diseases. We found that soluble proteins from lysates of H. pylori strains (SPLHP) recognition patterns in these sera were highly variable. Overall, IgG2 titres were higher than the IgG1 titres in the infected patients. In particular, those with peptic ulcers showed marked elevation in IgG2/IgG1 ratios, while SPLHPs from dyspeptic patients resulted in high IgG1 titres. Our results reveal that correlation of antibody subclass titres with Th1/Th2 markers may aid pathology characterization and show a potential diagnosis that could be formally evaluated in other studies.

CD74 in antigen presentation, inflammation, and cancers of the gastrointestinal tract

CD74 is a protein whose initial role in antigen presentation was recognized two decades ago. Recent studies have revealed that it has additional functions as a receptor for macrophage migration inhibitory factor and as a receptor for an important human pathogen, Helicobacter pylori (H pylori). The role of CD74 as a receptor is important because after binding of migration inhibitory factor or H pylori, NF-κB and Erk1/2 activation occurs, along with the induction of proinflammatory cytokine secretion. This review provides an up-to-date account of the functions of CD74 and how it might be involved in inflammation and cancer within the gastrointestinal tract.

The effects of probiotics on PPI-triple therapy for Helicobacter pylori eradication

BACKGROUND

This study was performed to evaluate whether the addition of probiotics to proton pump inhibitor (PPI)-based triple therapy increases the likelihood of successful Helicobacter pylori eradication.

MATERIALS AND METHODS

Three hundred and forty-seven H. pylori-infected patients were randomized into a triple-plus-yogurt group (yogurt group, n = 168) or a triple-only group (control group, n = 179). Triple therapy consisted of PPI b.i.d., clarithromycin 500 mg b.i.d., and amoxicillin 1 g b.i.d. for 7 days. Yogurt group received triple therapy for 1 week and one bottle of Will yogurt per day for at 3 weeks, starting on the first day of triple therapy. Will yogurt (a Korean brand) contains Lactobacillus acidophilus HY2177, Lactobacillus casei HY2743, Bifidobacterium longum HY8001, and Streptococcus thermophilus B-1. (13)C-urea breath test was performed at least 4 weeks after completion of triple therapy. Eradication rates, compliances, and adverse events were compared.

RESULTS

By intention-to treat analysis the H. pylori eradication rates in the yogurt group 79.2% (133 of 168) was similar to that in the control group 72.1% (129 of 179) (p = .124). However, by per-protocol (PP) analysis, the eradication rate in the yogurt group, 87.5% (133 of 152) was higher than that in the control group, 78.7% (129 of 164) (p = .037). Common adverse events were metallic taste (11.8%) and diarrhea (8.6%). The frequency of adverse effects in the yogurt group 41.1% (69/168) were higher than in the control group, 26.3% (47 of 179) (p = .003). However, most adverse events were mild to moderate in intensity, and the severities of adverse effects were similar in both groups (p = .401).

CONCLUSIONS

The addition of Will yogurt to triple therapy did not reduce the side-effects of triple therapy. But it increased the H. pylori eradication rate by PP analysis, encouraging more research in this field.

Experimental analysis of Helicobacter pylori transcriptional terminators suggests this microbe uses both intrinsic and factor-dependent termination

In this study, we report experimental analysis of transcriptional terminators in the human pathogen Helicobacter pylori. Previous bioinformatics approaches came to differing conclusions regarding transcriptional termination in this bacterium. We used a reporter construct, the tnpR-encoded resolvase, to assess terminators. In our first experiments, we found that a subset of previously predicted intrinsic terminators for H. pylori are functional. In our second experiments, we used an unbiased screen to identify putative terminators and then characterized 18 of these. We found that these putative terminators overlap genomic regions that are either intergenic or intragenic. Using reverse transcription PCR, we showed that an intergenic terminator and an intragenic antisense terminator function at their endogenous loci. Additionally, we found that putative terminators contain features of both intrinsic and Rho-dependent termination, but that intrinsic terminators define the majority. We were unable to delete rho, however, in H. pylori, suggesting that it is essential and likely important. Finally, we carried out a mutational analysis of one of our randomly identified terminators that has both intrinsic and Rho-dependent features, and found that they are both functional. In conclusion, we found that H. pylori possesses numerous Rho-dependent and intrinsic terminators including some found in intragenic regions.

Ten years after the first Helicobacter pylori genome: comparative and functional genomics provide new insights in the variability and adaptability of a persistent pathogen

In this review, we summarize how genomic approaches contributed to the understanding of the biology of the recently discovered pathogen Helicobacter pylori. Comparative genomics provided new insights into H. pylori's spectacular genetic diversity and generated exiting hypotheses on its evolutionary history. Transcriptomic studies provided original information on the mechanisms of H. pylori gastric adaptation that are central to its virulence.

CagA positivity and its association with gastroduodenal disease in Turkish children undergoing endoscopic investigation

BACKGROUND

Cytotoxin-associated gene A (CagA) product is a bacterial virulence factor contributing to the pathogenicity of Helicobacter pylori (HP) infection in humans. Host factors, which vary in different countries, interact with bacterial factors to determine the disease state. Our objective was to investigate the frequency of CagA-positive HP strains and evaluate the contribution of CagA positivity to symptoms and development of mucosal lesions in HP-infected Turkish children.

METHODS

We conducted a prospective clinical trial in 240 consecutive Turkish children undergoing endoscopy (110 girls, 130 boys; mean age, 8.7 +/- 4.3 years). HP infection was diagnosed on the basis of a positive rapid urease test and histology of the mucosal specimens. HP IgG and CagA IgG antibodies were measured by enzyme-linked immunosorbent assay in HP-positive children.

RESULTS

The HP positivity rate was 50.4% in our study group (51 girls, 70 boys; mean age, 9.9 +/- 3.9 years). CagA was positive in 74.4%. HP infection was less common in children with vomiting (25.9%, P < 0.05). CagA positivity was not associated with any clinical symptom. HP positivity was higher in children with duodenal ulcer (80% vs. 49.1%, P = 0.05); while CagA positivity was similar. Antral nodularity was strongly associated with HP positivity and CagA positivity (30.6% vs. 3.4% and 36.7% vs. 12.9%, respectively, P < 0.05). A negative association between CagA positivity and esophagitis was observed (20% vs. 76.7%, P < 0.05).

CONCLUSIONS

CagA positivity is common in HP-infected Turkish children. Esophageal lesions are less common in children infected with CagA-positive strains. Although HP is associated with duodenal ulcer disease, CagA positivity does not seem to contribute to development of ulcers in children in our series.

Carcinogenic role of tumor necrosis factor-alpha inducing protein of Helicobacter pylori in human stomach

Helicobacter pylori is the definitive carcinogen for stomach cancer and is known to induce proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1(IL-1) in the stomach. Based on our findings that TNF-alpha is an endogenous tumor promoter, we identified the TNFalpha inducing protein (Tipalpha) gene family, and confirmed Tipalpha and HP-MP1 as new carcinogenic proteins of H. pylori.Tipalpha protein is unique to H. pylori, and this paper shows the strong tumor promoting activity of Tipalpha gene family, in cooperation with Ras protein and its mechanisms of action in relation to NF-kappaB activation, and discusses the carcinogenic role of Tipalpha in stomach cancer. Our recent finding showing that penicillin-binding proteins of other bacteria are weak homologues of Tipalpha is also discussed.

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Review article: test and treat or test and scope for Helicobacter pylori infection. Any change in gastric cancer prevention?

A 'test and treat' strategy is advocated for patients with dyspepsia under the age of 45 years, with endoscopy reserved for those with alarm symptoms or aged over 45 years. One of the consequences of this strategy will be a reduction in population infection rates of Helicobacter pylori. It is now clear that H. pylori is one of the prime initiators of gastric cancer with up to 70% of gastric cancers attributable to H. pylori. What remains unclear is if H. pylori reduction will lead to a reduction in gastric cancer.

Analysis of the vacA, cagA, cagE, iceA, and babA2 genes in Helicobacter pylori from sixty-one pediatric patients from the Midwestern United States

This study was designed to characterize H. pylori from pediatric gastric biopsy specimens in terms of several genes (vacA, cagA, cagE, iceA1, iceA2, and babA2) proposed to be involved in the pathogenesis of this organism. Many of these genes have been studied in adult H. pylori isolates, however, these genes have not been well characterized in H. pylori from children. Using PCR we observed that 44% of the H. pylori in our biopsies shared two common genotypes (vacA s1b m1, cagA, cagE, iceA2 +/- babA2). While 26% of the H. pylori had unique genotypes. The cag pathogenicity island associated genes, cagA and cagE, were found together in 64% or our H. pylori, while 84% were iceA2 positive. The presence of the babA2 gene has been proposed to be associated with a higher risk of H. pylori related diseases, however, we found that only 36% of our H. pylori contained this gene.

Low Helicobacter pylori eradication rates with 4- and 7-day regimens in an Iranian population

BACKGROUND

In Iran, there is insufficient information on the efficacy of Helicobacter pylori eradication regimens shorter than 10 days. This study aims at assessing the efficacy of 4- and 7-day H. pylori eradication regimens in a high-incidence area of gastric cancer in Iran.

METHODS

Subjects with an endoscopic diagnosis of gastritis, positive urease test, and a histological diagnosis of chronic gastritis were enrolled. Patients were randomly assigned to one of three groups: AOC7 (1000 mg amoxicillin, 20 mg omeprazole, and 500 mg clarithromycin twice daily for 7 days), FOT4 (200 mg furazolidone, 20 mg omeprazole, and 500 mg tetracycline twice daily for 4 days) and FOT7 (the same treatment as the FOT4 group but for 7 days). Sensitivity to these antibiotics was determined in all isolates recovered from culture. The efficacy of eradication was assessed 8 weeks after the end-of-treatment by the 14C-urea breath test.

RESULTS

One hundred and twenty-eight patients were enrolled in the study. Culture was positive for 84 patients and none of these were resistant to amoxicillin, tetracycline or furazolidone, 1.2% were resistant to clarithromycin and 32.1% to metronidazole. Forty-five, 41 and 42 patients were randomly allocated to the AOC7, FOT4, and FOT7 groups, respectively. The intention-to-treat eradication rates were 35.5, 17.1, and 23.8% for the AOC7, FOT4, and FOT7 groups, respectively.

CONCLUSION

Treatment regimens of 4 or 7 days are unacceptable for H. pylori infection in Iran, even in the presence of a favorable sensitivity profile.

Gastroduodenal lesions in polycythaemia vera: frequency and role of Helicobacter pylori

The prevalence of gastroduodenal lesions is higher in polycythaemia vera (PV) than in the general population. However, the role of Helicobacter pylori (H. pylori) in the pathogenesis of such lesions is unknown. The aim of our study was to evaluate the prevalence of gastroduodenal lesions in PV patients and dyspeptic controls, and to assess the role of PV and H. pylori infection in inducing them. Thirty-five PV patients fulfilling selection criteria and 73 age- and sex-matched controls underwent upper gastrointestinal endoscopy. Six gastric mucosal biopsies were taken in all patients and controls, and analysed for presence of H. pylori; serum anti-CagA was assayed by Western blot. Data were analysed with descriptive statistics and multivariate regression analysis. Compared with controls, PV patients showed a significantly higher frequency of erosions (46% versus 12%), ulcers (29% versus 7%), H. pylori positivity (83% versus 57%), and anti-CagA positivity (66% versus 37%). Fourteen out of 20 (70%) asymptomatic PV patients had gastroduodenal lesions. At multivariate analysis, H. pylori, presence of PV alone, and both PV and anti-CagA were significantly and strongly associated with a higher frequency of gastroduodenal lesions (P < 0.05, P < 0.01 and P < 0.05 respectively). Both PV and H. pylori infection were independent risk factors for gastroduodenal lesions; the underlying pathogenetic mechanism responsible for gastroduodenal lesions in PV possibly involves blood mucosal flow and trophism. The higher susceptibility of H. pylori infection and the high frequency of asymptomatic gastroduodenal lesions in PV patients suggest a surveillance of these patients.

Helicobacter pylori eradication therapy is more effective in peptic ulcer than in non-ulcer dyspepsia

AIM

To evaluate whether eradication therapy is more effective in peptic ulcer disease (PUD) than in non-ulcer dyspepsia (NUD).

METHODS

We retrospectively studied 481 patients with NUD (183 patients) or PUD (298 patients) infected with Helicobacter pylori included in several prospective clinical trials. Three eradication regimens were given: (1) proton pump inhibitor (PPI) plus clarithromycin, plus either amoxycillin or metronidazole for 7 days (297 patients); (2) ranitidine bismuth citrate (RBC) plus clarithromycin plus amoxycillin for 7 days (79 patients); and (3) RBC plus clarithromycin plus amoxycillin plus metronidazole for 5 days (105 patients). H. pylori eradication was defined as a negative 13C-urea breath test 4 weeks after completing treatment.

RESULTS

H. pylori eradication rates were 82% (95% CI 78-87%) with PPI plus two antibiotics for 7 days, 85% (95% CI 75-91%) with RBC plus two antibiotics for 7 days, and 91% (95% CI 86-97%) with RBC plus three antibiotics for 5 days (P < 0.05 compared with the first regimen). Overall, the H. pylori eradication rate in patients with NUD was 78% (95% CI 71-84%), while in patients with PUD it was 89% (95% CI 86-93%) (P < 0.001). Both the combination of PPI plus two antibiotics for 7 days and the combination of RBC plus three antibiotics for 5 days were more effective in PUD than in NUD patients. However, RBC plus clarithromycin plus amoxycillin for 7 days was equally effective in both diseases. RBC plus two antibiotics for 7 days achieved better results than the same therapy with PPI only in NUD patients (84% v. 59%, P < 0.01), but both regimens were similar when prescribed in PUD patients (86% v. 88%). In the multivariate analysis, the type of therapy, the diagnosis (NUD v. PUD), and the product variable of therapy (with RBC plus 2 antibiotics for 7 days) and diagnosis (interaction variable) were the only variables that influenced H. pylori eradication. The odds ratio (OR) for the effect of RBC versus PPI plus two antibiotics for 7 days in patients with NUD was 4 (95% CI 1.7-9.7; P < 0.01), whereas in patients with PUD no statistical significance was achieved (OR 0.79; 95% CI 0.2-3.9).

CONCLUSION

Overall, H. pylori eradication therapy is more effective in PUD than in NUD patients. This advantage of eradication therapies in PUD patients seems to be observed with 7-day PPI-based triple regimens, and with 5-day RBC-based quadruple therapy, while the 7-day RBC-based triple regimen seems to be equally effective in both diseases.

Seropositivity against Helicobacter pylori CagA in Turkish gastric cancer patients

BACKGROUND

Increased prevalence of CagA in gastric cancer has been reported; yet, other reports suggest that the cagA gene is not associated with gastric cancer.

GOALS

To evaluate the frequency of CagA seropositivity in Turkish patients with gastric cancer.

STUDY

Thirty-two patients with gastric adenocarcinoma and 46 patients with nonulcer dyspepsia were examined for Helicobacter pylori status and for antibodies against CagA.

RESULTS

H. pylori was positive in 56.3% of patients and in 71.7% of controls. CagA was positive in all patients in the study group, regardless of H. pylori positivity, and in 56.5% of the control group. CagA positivity in H. pylori -positive patients was significantly more frequent in patients with gastric cancer than in those with nonulcer dyspepsia ( p < 0.001). As for H. pylori -negative patients in both groups, CagA positivity was also more frequent in gastric cancer patients ( p < 0.001).

CONCLUSION

Testing for H. pylori antibodies without testing for antibodies against CagA will miss patients with either recent or previous infection, which may be a cause of missing the relationship between H. pylori and gastric cancer. The authors think that testing for CagA in patients with dyspepsia can reveal which patients should be followed up for the risk of developing gastric cancer.

Helicobacter pylori "test-and-scope" strategy for dyspeptic patients. Is it useful and safe?

AIM

To evaluate outcome of test-and-scope strategy using 13C-urea breath test, Helicobacter pylori IgG serology, and CagA serology.

PATIENTS AND METHODS

A series of 100 dyspeptic patients were studied. Biopsies were obtained for histology and rapid urease test (gold standard). Serum samples were obtained for Helicobacter pylori IgG and CagA serology, and 13C-urea breath test was carried out.

RESULTS

If endoscopy had not been performed in Helicobacter pylori patients based on 13C-urea breath test, <45 years, without alarm symptoms, and without non-steroidal anti-inflammatory drug use, 15% of endoscopies would have been saved, and one gastric ulcer and two oesophagitis would have been missed. Based on Helicobacter pylori IgG serology, 21% of endoscopies would have been saved. Finally, if endoscopy had been performed only in CagA+ patients, 31% of endoscopies would have been saved, missing one gastric ulcer and two cases of oesophagitis.

CONCLUSIONS

In our geographical area, the test-and-scope strategy based on 13C-urea breath test or Helicobacter pylori IgG serology would have saved only 15-20% of endoscopies. Although some relevant pathology would have been missed, it is not of a malignant type. 13C-urea breath test is the preferred non-invasive method to be used in this strategy, while Helicobacter pylori IgG serology is of limited value due to its low accuracy. With the use of CagA serology a larger number of unnecessary endoscopic examinations can be avoided.

Development of early gastric cancer 4 and 5 years after complete remission of Helicobacter pylori associated gastric low grade marginal zone B cell lymphoma of MALT type

AIM: To report 3 of 120 patients on the German MALT lymphoma trial with H. pylori associated gastric MALT lymphoma who developed early gastric cancer 4 and 5 years, after complete lymphoma remission following cure of H. pylori infection.

PATIENTS AND RESULTS: Three patients (two men, 74 and 70 years; one women, 77 years) with H. pylori-associated low-grade MALT lymphoma achieved complete lymphoma remission after being cured. Surveillance endoscopies were performed twice a year in accordance to the protocol. Four years after complete lymphoma remission in two patients, and after 5 years in the other, early gastric adenocarcinoma of the mucosa-type, type II a and type II c, respectively, was detetcted, which were completely removed by endoscopic mucosa resection. In one patient, the gastric cancer was diagnosed at the same location as the previous MALT lymphoma, in the other patients it was detected at different sites of the stomach distant from location of the previous MALT lymphoma. The patients were H. pylori negative during the whole follow-up time.

CONCLUSION: These findings strengthen the importance of regular Long term follow-up endoscopies in patients with complete remission of gastric MALT lymphoma after cure of H. pylori infection. Furthermore, gastric adenocarcinoma may develop despite eradication of H. pylori.

CagA-positive strains of Helicobacter pylori may protect against Barrett's esophagus

OBJECTIVE

Helicobacter pylori (H. pylori) colonization is associated with chronic gastritis, peptic ulcer disease, and adenocarcinoma of the distal stomach. However, the role of H. pylori strain variation in complicated gastroesophageal reflux disease, especially Barrett's esophagus, is unknown. Therefore, the aim of this study was to evaluate the prevalence of colonization by cagA+ and cagA- H. pylori strains in the spectrum of gastroesophageal reflux disease, including Barrett's esophagus.

METHODS

A total of 251 patients undergoing endoscopy were categorized into four groups: controls, patients with gastroesophageal reflux disease alone, and patients with short- and long-segment Barrett's esophagus. All patients underwent upper endoscopies with biopsies and serum collections. H. pylori and degree of mucosal inflammation in gastric biopsies were assessed and serological assessment made for H. pylori and cagA status.

RESULTS

The overall prevalence of H. pylori colonization in the study population was 35% (95% confidence interval = 29.5-41.4%) which did not differ significantly among the groups. However, colonization by cagA+ H. pylori strains was significantly more prevalent among controls (11/25; 44%) and patients with gastroesophageal reflux disease (13/36; 36%) than in patients with short-segment (2/10; 20%) or long-segment Barrett's esophagus (0/18; 0%). Patients with Barrett's esophagus were less likely to be colonized by cagA+ H. pylori strains than reflux patients without Barrett's esophagus (odds ratio = 0.27, 95% confidence interval = 0.11-0.67, p = 0.004).

CONCLUSIONS

Colonization by cagA+ H. pylori strains may be protective against the formation of short- and long-segment Barrett's esophagus and its malignant complications.

Virulent strains of Helicobacter pylori demonstrate delayed phagocytosis and stimulate homotypic phagosome fusion in macrophages

Helicobacter pylori colonizes the gastric epithelium of approximately 50% of the world's population and plays a causative role in the development of gastric and duodenal ulcers. H. pylori is phagocytosed by mononuclear phagocytes, but the internalized bacteria are not killed and the reasons for this host defense defect are unclear. We now show using immunofluorescence and electron microscopy that H. pylori employs an unusual mechanism to avoid phagocytic killing: delayed entry followed by homotypic phagosome fusion. Unopsonized type I H. pylori bound readily to macrophages and were internalized into actin-rich phagosomes after a lag of approximately 4 min. Although early (10 min) phagosomes contained single bacilli, H. pylori phagosomes coalesced over the next approximately 2 h. The resulting "megasomes" contained multiple viable organisms and were stable for 24 h. Phagosome-phagosome fusion required bacterial protein synthesis and intact host microtubules, and both chloramphenicol and nocodazole increased killing of intracellular H. pylori. Type II strains of H. pylori are less virulent and lack the cag pathogenicity island. In contrast to type I strains, type II H. pylori were rapidly ingested and killed by macrophages and did not stimulate megasome formation. Collectively, our data suggest that megasome formation is an important feature of H. pylori pathogenesis.

[Antibodies against Helicobacter pylori in saliva. Study of their validity versus breath test and its agreement with serology]

OBJECTIVES

To evaluate prospectively the validity of a new diagnostic method based on a saliva sample, taking as reference the breath test with 13C-marked urea, and to compare the results of this technique with another indirect method based on the detection of antibodies, "classical" serology using venous blood.

METHODS

48 individuals, 24 healthy volunteers and 24 consecutive patients with gastro-duodenal ulcer disease, were studied prospectively. Treatment during the previous month with gastro-erosive medication, antibiotics, proton-pump inhibitors or bismuth-derived drugs, prior treatment to eradicate H. pylori, gastric surgery and the presence of linked illnesses, were all considered criteria of exclusion from the study. For the diagnostic test in saliva a commercial enzyme-linked immunosorbent assay (ELISA, trademark Helisal) was used; and for blood serology, another commercial ELISA (Helico-G). The staff responsible for reading the saliva, serology and breath tests did not know the result of the other diagnostic methods. The result of the breath test with 13C-urea (TAU-kit) was taken as the reference standard for H. pylori infection.

RESULTS

The mean age of the healthy volunteers was 23 +/- 0.7 years; and of ulcer patients, 55 +/- 18. The prevalence of H. pylori infection, valued by the gold standard, was 79.2% in the ulcer patients and 54% in the volunteers. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of the saliva test in the ulcer patients were, respectively: 100% (95% CI, 79-99), 60% (17-93), 90% (68-98), 100% (31-97) and 92% (71-98). In the volunteers these figures were: 46% (20-74), 73% (39-93), 67% (31-91), 53% (27-78) and 58% (37-77). The serology results were better, with 100% sensitivity in both groups and outstanding diagnostic accuracy (92% and 96% for ulcer patients and volunteers, respectively). Concordance between serology and the saliva test in ulcer patients was perfect (kappa, 1). However, in asymptomatic individuals concordance was deficient (kappa, 0.28), and the prevalence of infection diagnosed with the two tests was not homogeneous (McNemar, 2.8; p < 0.05).

CONCLUSION

The diagnostic test for H. pylori infection in saliva is lacking in diagnostic accuracy in healthy individuals, which indicates that it cannot be used for screening infection in the asymptomatic population. The technique is more valuable in ulcer patients, although it does not reach the specificity desirable. For these reasons, the saliva test evaluated in this study cannot be recommended for diagnosis of H. pylori infection.

Helicobacter pylori and gastroesophageal reflux disease

The nature of the relationship between Helicobacter pylori (Hp) infection and gastroesophageal reflux disease (GERD) remains unclear. This article reviews the current body of knowledge regarding the association between these two common entities. The authors examine the potential interactions of Hp and GERD from epidemiologic and pathophysiologic viewpoints and summarize and critique the prevalence and eradication studies that have been performed to date. Special consideration is given to the possible effects that long-term use of proton pump inhibitors may have on Hp gastritis.

Clinical relevance of the Helicobacter pylori gene for blood-group antigen-binding adhesin

Infection with Helicobacter pylori is associated with different human gastric diseases. Biochemical studies, in vitro adherence assays, and in vivo animal models revealed that epithelial attachment of H. pylori can be mediated by the blood-group antigen-binding adhesin (BabA) targeting human Lewis(b) surface epitopes. Studies with transgenic mice expressing the Lewis(b) epitope have shown that such attachment can alter disease outcome. In the current study, the presence of the babA2 gene encoding the adhesin was investigated in clinical isolates from a German population by using PCR and reverse transcription-PCR. A positive genotype was correlated to allelic variations in the genes encoding VacA and CagA and also to the prevalence of duodenal ulcer, distal gastric adenocarcinoma, mucosa-associated lymphoid tissue lymphoma, and antral gastritis. The presence of babA2 was significantly associated with duodenal ulcer (P = 0.0002) and adenocarcinoma (P = 0.033). In contrast, type 1 strains (vacAs1- and cagA-positive) were associated with only duodenal ulcer (P = 0.004) but not adenocarcinoma (P = 0.235). Genotype presence of babA2, vacAs1, and cagA ("triple-positive" strains) showed a highly significant correlation to the prevalence of ulcer (P = 0.000002) and adenocarcinoma (P = 0.014) and discriminated significantly better between disease outcome than did the current type 1 classification. These results indicate that the babA2 gene is of high clinical relevance and would be a useful marker to identify patients who are at higher risk for specific H. pylori-related diseases.

Host determinants of Helicobacter pylori infection and its clinical outcome

Greater than one-half of the world's population harbors Helicobacter pylori. The majority of infected individuals, however, remain asymptomatic, with only 10% to 20% developing diseases, including peptic ulcer disease, gastric cancer, and gastric mucosa-associated lymphoid tissue lymphoma. This article reviews host factors that may predispose an individual to both the acquisition of H. pylori infection and subsequent clinical outcome. Individuals with specific blood group antigens and human leukocyte antigen genotypes may be more susceptible to H. pylori infection. Additional factors, such as the age of acquisition, the host immune response, the site of infection, acid secretion, and interactions with nonhost factors (including bacterial virulence factors and environmental influences) may play a role in determining clinical outcome. Further investigation is required to clarify the mechanisms by which these interactions occur and, more critically, to determine their relative importance. This knowledge will enable the identification of individuals at risk of developing clinical disease with H. pylori infection.

Rapid genomic diversification of Helicobacter pylori

Helicobacter pylori was cultured from antrum and corpus gastric biopsies from 65 patients originating from two separate groups: (i) a geographically linked group and (ii) a geographically nonlinked group. Genomic DNA was recovered from the clinical isolates and subjected to restriction fragment length polymorphism (RFLP) analysis after digestion with DraI. Southern blots were probed with the oligonucleotide (GTG)5, the riboprobe pKK3535, and the cagA gene probe pMC3. (GTG)5 and cagA DNA fingerprints and ribopatterns suggested that most of the patients were infected with their own unique strain; however, some were infected with multiple strains. Minor genomic differences were detected in many antrum/corpus sample pairs (clonal variants), suggesting rapid evolutionary change in domains detected by (GTG)5. The high degree of genomic diversity detected by (GTG)5 may reflect structural versatility of these domains. The genomic diversity indicates that infection by H. pylori in a defined community does not appear to be limited to certain RFLP types.

Lack of a relationship between Lewis antigen expression and cagA, CagA, vacA and VacA status of Irish Helicobacter pylori isolates

The cagA gene, vacA gene, CagA (cytotoxin-associated gene A product) and VacA (vacuolating cytotoxin) status of a collection of Helicobacter pylori isolates from the geographically distinct Irish population was determined, the potential association of these traits with Lewis (Le) antigen expression was assessed, and the relationship between these bacterial properties and the pathology associated with H. pylori infection was evaluated. Of the 57 isolates, a higher proportion from ulcer than from non-ulcer patients expressed VacA (71% vs. 53%). H. pylori isolates which were cagA-positive were no more significantly associated with peptic ulcers than non-ulcer disease (71% vs. 67%, P = 0.775), nor were CagA-positive isolates (57% vs. 50%, P = 0.783), but 80% of the isolates from duodenal ulcer patients were cagA-positive. Thirty-seven of the 57 isolates were tested for Le antigen expression. No statistically significant relationship (P > 0.05) was found between the occurrence and level of expression of Le(x) or Le(y) and cagA, vacA, or VacA status. This lack of an association in the Irish H. pylori isolates contrasts with that previously reported for predominantly North American isolates, and may be attributable to the adaptation of H. pylori strains with differing attributes to different human populations.

Helicobacter pylori non-cytotoxic genotype enhances mucosal gastrin and mast cell tryptase

AIMS

To determine the association, if any, between H pylori genotype and the gastric mucosal variations in the levels of gastrin, somatostatin, tryptase, and histamine.

METHODS

49 patients affected by duodenal ulcer and 48 by non-ulcer dyspepsia were studied. To identify the H pylori genotype, the presence of the cagA gene and vacA alleles m1, m2, s1, and s2 were analysed by polymerase chain reaction. Gastrin, somatostatin, tryptase, and histamine were measured in antral mucosal biopsies.

RESULTS

57 patients were infected with H pylori (30 with duodenal ulcer and 27 with non-ulcer dyspepsia). Gastrin and tryptase were increased in patients with H pylori infection, although the variations were statistically significant only for gastrin; somatostatin and histamine were not influenced by H pylori infection. In patients with non-ulcer dyspepsia the absence of the cagA gene and the presence of vacA alleles s2 and m2 were associated with higher values of tryptase and to a lesser extent of gastrin. These associations were not found in patients with duodenal ulcer.

CONCLUSIONS

The cagA negative s2m2 strain of H pylori may be less dangerous for the gastric mucosa than other H pylori strains since it enhances tryptase production by gastric mucosal mast cells; this enzyme is thought to stimulate tissue turnover and favour wound healing.

The prevalence of antibody to CagA in children is not a marker for specific disease

BACKGROUND

In adults, a high prevalence of antibody to the cytotoxin-associated antigen (CagA) of Helicobacter pylori has been linked to the development of more serious gastroduodenal disease. Few investigators have examined this association in children. The purpose of this study was to investigate the seroprevalence of antibody to the CagA antigen as well as other specific H. pylori antigens in children.

METHODS

By use of an immunoblot analysis kit, the immune response to specific H. pylori antigens in serum collected from 21 H. pylori-positive symptomatic Australian children, 5 with peptic ulcer disease and 16 with nonulcer dyspepsia, and 33 H. pylori-positive asymptomatic Chinese children. Sera from 20 H. pylori-negative symptomatic Australian children were used as control subjects.

RESULTS

Antibody responses to the 26.5-kDa, 30-kDa, and 116-kDa (CagA) antigens were found to be the most prevalent, with 81.5%, 79.6%, and 76% of children, respectively, mounting a response. In contrast, antibody responses to the 19.5-kDa, 35-kDa, 45-kDa, 60-kDa, 89 kDa (VacA), and 180-kDa antigens occurred in 55.5%, 24%, 16.7%, 63%, 37%, and 7.4% of children, respectively. A higher prevalence of antibody response to CagA was found in the symptomatic Australian children with peptic ulcer disease (100%) compared with prevalence in those with nonulcer dyspepsia (56.3%), but the difference did not reach statistical significance. No significant difference was found between the prevalence of antibody to CagA in the Australian peptic ulcer disease group (100%) and that in the asymptomatic Chinese children (81.8%).

CONCLUSION

These results suggest that in children CagA is not a marker of specific disease development.

Helicobacter pylori cagA status and s and m alleles of vacA in isolates from individuals with a variety of H. pylori-associated gastric diseases

The cagA gene was detected in 100% of 16 Helicobacter pylori isolates from patients with gastric carcinoma versus 78% of 18 isolates from patients with duodenal ulcers (P = 0.344) and only 64% of 22 isolates from patients with gastritis only (P = 0.005) in Brazil. Also, there was a significant association between isolation of cagA+ s1-type vacA H. pylori in cases of stomach cancer and ulcers as opposed to cases of gastritis only (P = 0.004), but this was not true in Houston (P = 0.238), where 94% of all isolates were cagA+.

Lack of correlation between vacuolating cytotoxin activity, cagA gene in Helicobacter pylori, and peptic ulcer disease in children

To determine the prevalence of the cagA gene and vacuolating cytotoxin in Helicobacter pylori isolates obtained from children and to characterize the relationship between cagA, cytotoxin production, and ulcerogenesis, pediatric Helicobacter pylori isolates were tested for cagA by the polymerase chain reaction and for vacuolating cytotoxin by a cell culture assay. Helicobacter pylori isolates were obtained from 33 children referred for upper gastrointestinal endoscopy. Twenty-six of these isolates were tested for cagA by the polymerase chain reaction; all 26 (100%) were positive. Of the 26 children from whom these isolates were obtained, 26 (100%) had chronic gastritis and 12 (46%) had duodenal ulcers. Nine (30%) of 30 isolates tested showed expression of vacuolating cytotoxin, only three of which came from patients with duodenal ulceration (odds ratio 0.81, 95% confidence interval 0.1-5.3). Of the 23 cagA-positive isolates tested for cytotoxin, only nine (39%) were positive. There was no association between vacuolating cytotoxin and clinical symptoms, nor was cytotoxicity associated with ulcerogenesis. In summary, the findings suggest that cagA is not a marker of duodenal ulceration or of vacuolating cytotoxin production in children referred for endoscopy.

High frequency of CagA+ Helicobacter pylori infection in high-grade gastric MALT B-cell lymphomas

A high incidence of Helicobacter pylori infection has been found in patients with gastric MALT (mucosa-associated lymphoid tissue) B-cell lymphoma. Recent studies have indicated that the aggressive strains of the bacterium containing the CagA gene may have direct effects on tumourigenesis. To investigate the involvement of CagA+ strains in MALT lymphomagenesis, a sensitive polymerase chain reaction (PCR)-based detection assay for the gene was developed. DNA extracts from paraffin sections of 123 H. pylori-related gastric biopsies from Italy were analysed, including 56 cases of chronic gastritis, 37 low-grade, and 30 high-grade MALT lymphomas: 30.3 per cent (17/56) of the gastritis cases, 37.8 per cent (14/37) of the low-grade, and 76.7 per cent (23/30) of the high-grade MALT lymphomas were found to contain the CagA gene. The frequency of CagA+ strain infection was significantly higher (P < 0.05) in high-grade than in low-grade MALT lymphoma or gastritis. These results suggest that high-grade gastric MALT lymphoma transformation may be more likely to occur following infection by CagA+ strains of H. pylori.

Antibody response to specific H. pylori antigens in functional dyspepsia, duodenal ulcer disease, and health

OBJECTIVE

The relationship between H. pylori and functional dyspepsia remains controversial. The aim of this study was to identify a potential link between the antibody response to specific H. pylori antigens and functional dyspepsia.

METHODS

A total of 50 consecutive patients with functional dyspepsia, 50 patients with duodenal ulcer (DU), and 150 healthy blood donor control subjects with no history of peptic ulceration were studied. H. pylori status was determined by IgG antibodies using a validated ELISA. In H. pylori-positive subjects, antibodies against specific H. pylori antigens were identified by Western blot.

RESULTS

All DU patients (100%; 95%; CI, 93-100), 30 of 50 patients with functional dyspepsia (60%; 95% CI, 45-74) and 65 of 150 (43.3%; 95% CI, 34.3-51) blood donor controls tested positive for H. pylori. Forty-six of 50 (92%; 95% CI, 81-98) DU patients tested positive for the 91 kDa antigen (vacA) compared with 46 of 65 (69%; 95% CI, 58-81) control subjects and 22 of 30 (73%; 95% CI, 54-88) functional dyspepsia patients (p < 0.01 DU versus controls). Similarly, the 120 kDa antigen (cagA) tended (p < 0.15) to be more prevalent in DU patients (82%; 95% CI, 69-91) compared with controls (69%; 95% CI, 57-80) but not functional dyspepsia (77%; 95% CI, 57-90). No specific H. pylori antigens were associated with dyspepsia subgroups.

CONCLUSION

No specific H. pylori antigens are linked to functional dyspepsia.

The seroprevalence of cagA-positive Helicobacter pylori strains in the spectrum of gastroesophageal reflux disease

BACKGROUND & AIMS

The role of Helicobacter pylori in the pathogenesis of gastroesophageal reflux disease (GERD) is unknown. We determined the prevalence of cagA-positive (cagA+) H. pylori strains in patients with GERD or its complications compared with controls of similar age.

METHODS

A total of 153 consecutive patients with GERD, Barrett's esophagus, and Barrett's esophagus complicated by dysplasia or adenocarcinoma were compared with 57 controls who underwent upper endoscopy for reasons other than GERD. H. pylori infection and CagA antibody status were determined by histology and enzyme-linked immunosorbent assay.

RESULTS

H. pylori prevalence was lower (34%) in patients with GERD and its sequelae than in the control group (45.6%)(P = 0.15). Regardless of the group, increasing age was associated with higher prevalence of H. pylori (P = 0.003). When compared with controls (42.3%), the prevalence of cagA+ H. pylori strains decreased (P = 0.008) in patients with more severe complications of GERD (GERD, 36.7% [nonerosive GERD, 41.2%; erosive GERD, 30.8%]; Barrett's esophagus, 13.3%; and Barrett's with adenocarcinoma/dysplasia, 0%).

CONCLUSIONS

Prevalence of H. pylori in patients with GERD and its sequelae was lower but not significantly different than that of a control group. However, patients carrying cagA+ strains of H. pylori may be protected against the complications of GERD, especially Barrett's esophagus and its associated dysplasia and adenocarcinoma.

Antigenic diversity and serotypes of Helicobacter pylori associated with peptic ulcer diseases

OBJECTIVES

Clinical presentation of Helicobacter pylori (H. pylori) infection has marked variation mainly due to the strain diversity and host susceptibility. Although H. pylori is identified as a major risk factor for gastric and duodenal ulcers, the ulcerogenic or pathogenic strain has not been documented yet. The objective of this study was to investigate antigenic types of the ulcerogenic strain of H. pylori.

METHODS

The sera of 64 patients were tested by Western blot using Helicoblot 2.0 for six major anti-H. pylori antibodies, together with CLO test and histological examination of gastric biopsy tissues. Thirty-five, nine and 20 patients had duodenal ulcer, gastric ulcer and chronic active gastritis, respectively. The antigenic types of H. pylori were analyzed in 54 patients with positive H. pylori infection. In this study, H. pylori was divided into four serotypes according to the presence and absence of CagA and VagA: type I; CagA (+) and VacA(+), type Ia: CagA (+) and VacA(-), type Ib: CagA(-) and VacA(+), and type II: CagA(-) and VacA(-).

RESULTS

There was no difference in the number of bands for six antigens: 3.2 +/- 1.4, 3.0 +/- 1.2 and 3.1 +/- 1.4 in 35 duodenal ulcer, 7 gastric ulcer and 12 chronic gastritis, respectively. The band with 119 kDa was 90.7%, which was the most common band with the order of 35, 30, 26.5, 89 and 19.5 kDa. Type I, la and Ib were positive in 22.2, 42.6 and 27.8%, respectively, which were significantly higher than type II (p < 0.05). There was no difference in the positive rates of four urease subtypes between the four serotypes.

A review of the possible bacterial determinants of clinical outcome inHelicobacter pyloriinfection

Helicobacter pylori is present in 40-60% of the population and approximately 10-20% of these infected individuals suffer from a H. pylori associated disease such as peptic ulcer disease or gastric cancer. This article reviews the potential bacterial determinants responsible for and markers predictive of both the acquisition of H. pylori infection and subsequent clinical outcome; i.e., asymptomatic infection or disease. The acquisition of H. pylori infection depends on exposure (hence the increased risk in lower socioeconomic groups and developing nations) to viable bacteria with at least a functional urease gene in a susceptible host. Once infection occurs, bacterial virulence factors, including the vacuolating cytotoxin, and genes of the cag pathogenicity island, as well as nonbacterial factors may determine disease outcome. Future research is being directed at discovering other bacterial virulence factors responsible for the different clinical outcomes of H. pylori infection. This will be greatly enhanced by the recent release of the complete genome sequence of H. pylori. The determination of the relative importance of each of these recognized and other as yet unrecognized factors responsible for disease outcome will assist in the appropriate targeting of patients in the treatment of H. pylori infection.Key words: Helicobacter pylori, genetics, virulence, bacterial.

Helicobacter pylori cytotoxic genotype is associated with peptic ulcer and influences serology

OBJECTIVE

We studied 146 patients with peptic ulcer disease (n = 72), antral gastritis (n = 58), or duodenitis (n = 16) to ascertain whether the cytotoxic genotype of Helicobacter pylori (Hp) is associated with peptic ulcer disease and/or antral gastritis and whether it influences the circulating levels of total anti-Hp antibodies, anti-cagA antibodies, and pepsinogens.

METHODS

A gastric juice sample was obtained from each patient. After DNA extraction, polymerase chain reaction was used to amplify the genes urease A (ureA), cagA, and vacA of Hp.

RESULTS

A significant association was found between peptic ulcer disease and the cytotoxic genotypes, characterized by the presence of s1 and m1 alleles of vacA and by cagA. Patients with a cagA-positive genotype showed a significant increase in anti-cagA antibodies and also had significantly increased circulating levels of pepsinogen C.

CONCLUSIONS

Cytotoxic Hp strains are mainly involved in determining peptic ulcer disease, but not antral gastritis. The higher levels of circulating pepsinogen C found in patients infected with cytotoxic genotypes may reflect the higher degree of inflammation sustained by these strains.

How does Helicobacter pylori cause mucosal damage? Direct mechanisms

Helicobacter pylori-associated gastritis is characterized by an abundant inflammatory response and gastric epithelial cell injury. Adherence of H. pylori to gastric epithelial cells seems to be required for bacterial colonization of the gastric mucosa. Attachment of the bacterium to polarized gastric epithelial cells causes damage to microvilli and stimulates actin polymerization, which is associated with adherence pedestal formation. Studies suggest that H. pylori directly contributes to the injury of gastric epithelial cells by the elaboration of cytotoxic factors. The first toxin identified from H. pylori strains, known as vacuolating cytotoxin, induces vacuole formation in eukaryotic cells. Elaborated enzymes by H. pylori may also contribute directly to epithelial cell injury. Ammonia produced through urease activity may be toxic to gastric epithelial cells. H. pylori protease and lipase degrade gastric mucus and disrupt the phospholipid-rich layer at the apical epithelial cell surface, allowing for cell injury from back diffusion of gastric acid. This cell injury may lead to cell death, believed to result from induction of apoptosis. There are sufficient data to suggest that H. pylori, through direct pathogenic mechanisms, contributes significantly to the gastric mucosal injury associated with this infection, and may enhance the susceptibility of gastric epithelial cells to carcinogenic conversion.

Hematoxylin and eosin staining of gastric tissue for the detection of Helicobacter pylori

BACKGROUND

Gold standard methods of detection of Helicobacter pylori are expensive, difficult to perform, or not widely available. The purpose of this study was to assess hematoxylin and eosin staining of antral tissue, a relatively inexpensive and widely available method of H. pylori detection.

MATERIALS AND METHODS

The hematoxylin and eosin stain was assessed as a method of H. pylori detection, with 2 x 2 table analysis using culture as the gold standard in 133 gastric biopsy specimens obtained from patients both before and following attempted eradication.

RESULTS

Performance of the stain was good among untreated patients as well as among patients having previously undergone an eradication treatment, with an overall accuracy of 92% (95% confidence intervals: 86-96), sensitivity of 93% (87-97), and specificity of 87% (69-96).

CONCLUSION

The hematoxylin and eosin stain is an inexpensive method of H. pylori detection but with test performance characteristics inferior to Giemsa, Genta, or silver stains.