Campylobacter pyloridis in peptic ulcer disease: microbiology, pathology, and scanning electron microscopy

Galectin-2 Has Bactericidal Effects against Helicobacter pylori in a β-galactoside-Dependent Manner

Helicobacter pylori is associated with the onset of gastritis, peptic ulcers, and gastric cancer. Galectins are a family of β-galactoside-binding proteins involved in diverse biological phenomena. Galectin-2 (Gal-2), a member of the galectin family, is predominantly expressed in the gastrointestinal tract. Although some galectin family proteins are involved in immunoreaction, the role of Gal-2 against H. pylori infection remains unclear. In this study, the effects of Gal-2 on H. pylori morphology and survival were examined. Gal-2 induced H. pylori aggregation depending on β-galactoside and demonstrated a bactericidal effect. Immunohistochemical staining of the gastric tissue indicated that Gal-2 existed in the gastric mucus, as well as mucosa. These results suggested that Gal-2 plays a role in innate immunity against H. pylori infection in gastric mucus.

Higher glucose level can enhance the H. pylori adhesion and virulence related with type IV secretion system in AGS cells

BACKGROUND

Hyperglycemia increases the risk of gastric cancer in H. pylori-infected patients. High glucose could increase endothelial permeability and cancer-associated signaling. These suggest high glucose may affect H. pylori or its infected status.We used two strains to investigate whether H. pylori growth, viability, adhesion and CagA-phosphorylation level in the infected-AGS cells were influenced by glucose concentration (100, 150, and 200 mg/dL).

RESULTS

The growth curves of both strains in 200 mg/dL of glucose were maintained at the highest optimal density after 48 h and the best viability of both strains were retained in the same glucose condition at 72 h. Furthermore, adhesion enhancement of H. pylori was significantly higher in 200 mg/dL of glucose as compared to that in 100 and 150 mg/dL (p < 0.05). CagA protein also increased in higher glucose condition. The cell-associated CagA and phosphorylated-CagA was significantly increased in 150 and 200 mg/dL of glucose concentrations as compared to that of 100 mg/dL (p < 0.05), which were found to be dose-dependent.

CONCLUSION

Higher glucose could maintain H. pylori growth and viability after 48 h. H. pylori adhesion and CagA increased to further facilitate the enhancement of cell-associated CagA and phosphorylated CagA in higher glucose conditions.

Sequence and apoptotic activity of VacA cytotoxin cloned from a Helicobacter pylori Thai clinical isolate

The vacuolating cytotoxin VacA produced by Helicobacter pylori induces the formation of large cytoplasmic vacuoles in host gastric epithelial cells as well as a release of cytochrome C from mitochondria resulting in cell apoptosis. Considerable sequence diversity in VacA relating to different degrees of disease severity is observed with clinical samples from a multitude of geographic places. In this study we describe expression in Escherichia coli, purification to homogeneity and in vitro assay of its apoptotic activity of a VacA toxin from a H. pylori isolate of a Thai patient with gastrointestinal lymphoma. Sequencing revealed that the deduced amino acid sequence of the cloned Thai isolate VacA is similar to H. pylori s1/m2 type strains. The percent sequence similarity to the model strain 60190 was lower due to the presence of extra amino acids in the mid (m) region. The purified VacA toxin exhibited significant apoptotic activity on both T84 and MDCK epithelial cell lines, as revealed by DAPI staining, whereby the observed activity was significantly higher on MDCK cells. These findings could relate to a modulation of VacA activity on host cells in the Thai isolate-VacA toxin that may differ from those of the model strain.

Significance of Campylobacter pylori

There is an explosion of interest in the role of Campylobacter pylori as a cause of active chronic gastritis. This curved spiraled microorganism can readily be detected within the mucus gel covering the stomach mucosa, especially in patients suffering from peptic ulcer disease or non-ulcer dyspepsia. To what extent this intriguing microorganism is causally related to peptic ulcer disease remains to be elucidated, but all the evidence which is available so far supports a pathogenetically important role. There appears to be a striking discordance between in-vitro sensitivity and in-vivo efficacy of antibiotic therapy. At present, the combination of colloidal bismuth subcitrate and amoxycillin or tinidazole appears most effective in temporary elimination of these microorganisms.

Helicobacter pylori: review of research findings

Helicobacter pylori attracted widespread interest from gastroenterologists because of its potential aetiologic role in disorders of the upper gastrointestinal tract. Based on extensive microbiological studies, Campylobacter pylori was renamed Helicobacter pylori, and the organism represents a new genus of bacteria. It is generally accepted that H. pylori causes chronic, non-specific gastritis (type B gastritis). The inflammatory response occurs even though the bacterium does not penetrate the gastric epithelium; it is found on the surface of and adjacent to the epithelium. The clinical significance of histological gastritis is unknown. The bacterium is often found in asymptomatic subjects. In Caucasian adults, the prevalence of infection increases with increasing age. Higher rates of infection are found in blacks and Hispanics than would be expected for their age. Whether these different rates are the result of racial or socioeconomic factors is not known. It is theorized, but not proven, that high rates of infection with H. pylori at an early age may explain the high incidence of gastric carcinoma found in Hispanic populations. H. pylori is found in almost every patient with duodenal ulcer disease, although no direct evidence for a causal relationship exists. Indirect evidence is based on the findings that if H. pylori infection is eradicated, ulcer recurrence is less likely (up to one year of follow-up). A small percentage of patients have a relapse despite eradication of the organism, suggesting a role for other factors in duodenal ulcer disease. The role of H. pylori in gastric ulcer disease is unknown. Seventy to eighty per cent of patients with gastric ulcer have evidence of H. pylori infection, and preliminary data seem to support the existence of two distinct aetiologic groups: those with gastric ulcers related to H. pylori infection and those with gastric ulcers related to use of non-steroidal anti-inflammatory drugs. The role of H. pylori in non-ulcer dyspepsia is unknown. Some clinicians believe that H. pylori causes non-ulcer dyspepsia and treat these patients for H. pylori infection. However, the data supporting this practice are poor. Treatment is only recommended for patients with resistant duodenal ulcers and patients who have frequent relapses of duodenal ulcers and who are willing to take triple-drug therapy (bismuth compounds, metronidazole, tetracycline) for the infection. As 95% of patients with duodenal ulcer have evidence of H. pylori infection, there is probably little need to confirm the diagnosis of H. pylori infection.

Sphingomyelinase of Helicobacter pylori-induced cytotoxicity in AGS gastric epithelial cells via activation of JNK kinase

The aim of this study was to determine whether the Helicobacter pylori-derived sphigomyelinase (SMase) affects the sphingomyelin pathway and growth in AGS epithelial cells. We showed that the exogenous SMase increased the intracellular level of ceramide in AGS cells and led to rapid stimulation of extracellular signal-regulated kinase (ERK) and c-Jun kinase (JNK) activities. Incubation of AGS cells with H. pylori-derived SMase also resulted in suppression of cell growth and a concomitant induction of apoptosis. Data showed that PD98059 (up to 50 microM), an ERK inhibitor, did not affect the cell viability, whereas the cytotoxicity of exogenous SMase was completely blocked by SP600125, a JNK inhibitor at a concentration of 210 nM. We conclude that the activation of the mitogen-activated protein (MAP) kinases in AGS cells by exogenous H. pylori SMase is a major pathway to mediate the cytotoxicity.

What is the best method to diagnose Helicobacter infection in bleeding peptic ulcers?: a prospective trial

BACKGROUND

It has been debated which diagnostic test should be preferred for the diagnosis of Helicobacter pylori (HP) in patients with peptic ulcer diseases. Several limitations are reported in bleeding peptic ulcers because of intragastric blood and possibility of changed numbers of organisms by medication. This study was designed to find out the best method for diagnosis of HP infection, in aspect of deciding the times of detection and the specific tests in bleeding peptic ulcers.

METHODS

We prospectively examined histology, rapid urease test (CLO test), urea breath test (13C-UBT) and serology in HP diagnostics in 32 patients with bleeding peptic ulcers to detect HP infection. Each test was performed two times (four methods at first 24 hours and former three methods at 7th day after initial therapeutic endoscopy). We evaluated the sensitivity of each test, compared the two-times results and evaluated the effect of these tests to an outcome of endoscopic hemostasis.

RESULTS

Diagnostic sensitivities of histology, CLO test, 13C-UBT and serology are 75%, 67.8%, 100% and 100% at first endoscopy, and 71.4%, 78.5%, 89.3% at 7th day endoscopy, respectively. Histologic study and CLO test had diagnostic limitation at emergent first endoscopy contrary to UBT (p < 0.01). Histologic study, CLO test and UBT have limitations at 7th day endoscopy. Only 3 patients (9.4%) rebled with subsequent complete endoscopic hemostasis and all diagnostic tests at initial endoscopy did not influence the outcome of hemostasis.

CONCLUSION

First day histologic and CLO tests are inadequate methods in detecting HP infection in patients with bleeding peptic ulcers. 7-day histologic, CLO test and UBT have a low sensitivity. First-day UBT can be a standard test to diagnose HP infection in patients with bleeding peptic ulcers.

Colonization of Mexican patients by multiple Helicobacter pylori strains with different vacA and cagA genotypes

Helicobacter pylori virulence determinants have not previously been studied in detail in Latin Americans with H. pylori infections. We characterized the vacA (vacuolating cytotoxin gene A) and cagA (cytotoxin-associated gene A) types of more than 400 single-colony isolates from 20 patients in Mexico City. For 17 patients H. pylori strains of two or more different vacA genotypes were isolated from gastric biopsy specimens, indicating infection with two or more strains of H. pylori. The most frequent vacA genotype was s1b/m1. vacA diversity was more marked than that described previously, in that isolates from seven patients had untypeable vacA midregions and isolates from nine patients had type s1 signal sequence coding regions which could not be further subtyped. Previously undescribed vacA type s2/m1 strains were found in five patients. All patients were infected with cagA-positive strains, but occasionally, these coexisted with small numbers of cagA-negative strains. In conclusion, coinfection with multiple H. pylori strains is common in Mexico, and vacA in these strains is genetically more diverse than has been described in other populations.

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.

Comparison of invasive and noninvasive tests for detecting Helicobacter pylori infection in bleeding peptic ulcers

BACKGROUND

Eradication of Helicobacter pylori infection has been shown to prevent recurrent bleeding from peptic ulcers. However, the detection rate for H pylori infection seems to be underestimated in this group of patients and has been scarcely investigated.

METHODS

Eighty patients with bleeding peptic ulcer were studied for evidence of H pylori infection. Seventy-seven of these patients were enrolled as having H pylori infection after any one of the following 3 tests were positive: culture, histologic study, or any 2 of rapid urease test (CLO test), carbon 13-labeled urea breath test (UBT), and serologic examination. Fresh blood or blood-containing material in the gastric antrum was noted by panendoscopy in 22 patients (group A). In the remaining 55 cases there was no blood in the antrum (group B).

RESULTS

The sensitivities of the CLO test, bacterial culture, histologic study, 13C-labeled UBT, and immunoglobulin G serologic test were 45.5%, 36.4%, 77.2%, 95.4%, and 100% in group A, respectively, and 70.9%, 40.0%, 70.9%, 92.7%, and 96.4%, respectively, in group B. There was a statistically significant difference between the sensitivities found for CLO test and 13C-labeled UBT (p < 0.05). Of these 5 tests, only the sensitivity of the CLO test showed a statistically significant difference between groups A and B (p < 0.05). A delayed positive CLO test result was recorded in 13 patients (3 in group A, 10 in group B).

CONCLUSION

Noninvasive tests seemed to be more sensitive than invasive tests in detecting H pylori infection in patients with bleeding peptic ulcers. Blood in the antrum might reduce the sensitivity of the CLO test but have no effect on the other tests. The CLO test should be observed for more than 24 hours because of the possibility of a delayed positive result in some patients with bleeding peptic ulcers.

Hypothesis: cis-unsaturated fatty acids as potential anti-peptic ulcer drugs

It is now reasonably well established that Helicobacter pylori is the most likely cause for duodenal ulcer. What is not clear is how this infection is related to the excess acid production, why few people with Helicobacter pylori infection have duodenal ulcer and how diet is related to duodenal ulcer. Here it is suggested that a deficiency of cis-unsaturated fatty acids (otherwise called as polyunsaturated fatty acids, PUFAs) especially gamma-linolenic acid, dihomo-gamma-linolenic acid, arachidonic acid and eicosapentaenoic acid may be responsible for duodenal ulcer. Patients with active duodenal ulcer are known to have low concentrations of these PUFAs in their plasma phospholipid fraction and they revert to normal levels after treatment with H2 blockers. In addition, these PUFAs have the ability to inhibit the growth of Helicobacter pylori, suppress acid production and both in experimental animals and humans these PUFAs could heal the ulcer and protect the gastric mucosa from aspirin and steroid-induced damage. Further, PUFAs have other beneficial actions such as capacity to prevent/arrest atherosclerosis, lower plasma cholesterol and triglyceride levels and cytotoxic action on tumour cells. Since PUFAs can be administered over long periods of time and are relatively non-toxic, it is suggested that PUFAs may be exploited as potential anti-ulcer agents.

Identification of neutral and acidic sphingomyelinases in Helicobacter pylori

We demonstrated for the first time the presence of sphingomyelinase (SMase) in Helicobacter pylori. Activation of SMase has been implicated as the cause of elevation of cellular ceramide levels and consequently of apoptosis. The data indicate that there are two classes of SMase, defined by their optimal pHs and cellular locations, existing in H. pylori. One is an Mg(2+)-dependent membrane-bound enzyme with an optimal activity at pH 7, and the other is an Mg(2+)-independent cytosolic enzyme with an optimal activity at pH 5. Bisalumin, a bismuth salt, was found to inhibit the activities of both forms of SMase regardless of the presence of Mg2+. By Western blot analysis, the membrane-bound SMases of H. pylori and Bacillus cereus were shown to be antigenically related and to have a similar denatured molecular mass of 28 kDa.

Gastrointestinal diseases in women

Gastrointestinal disorders are among the most common disorders for which women seek medical attention. Most gastrointestinal diseases in women are not inherently different from those that occur in men. There are several disorders, however, that occur more frequently or manifest themselves differently in women. This article reviews common gastrointestinal disorders affecting women. The pathophysiology, clinical manifestations, management, and gender-specific issues of gastroesophageal reflux disease, peptic ulcer disease, irritable bowel syndrome (IBS), and inflammatory bowel disease (IBD) are discussed.

Helicobacter pylori infection and adenocarcinoma arising in Barrett's esophagus

Helicobacter pylori infection has been implicated in the development of chronic active gastritis and gastric neoplasms (ie, mucosa-associated lymphoid tumors and adenocarcinoma). The potential association between esophageal H pylori infection with Barrett's esophagus-associated adenocarcinoma has not been previously studied. Nineteen cases of adenocarcinoma arising in Barrett's esophagus were examined for the presence of H pylori. Barrett's esophagus was defined by the presence of metaplastic specialized-type epithelium (gastric-type epithelium with goblet cell metaplasia) in the distal esophagus. To detect the presence of H pylori, 5-microm sections, from several tissue blocks in each case, were stained with routine hematoxylin-eosin, modified Giemsa, and an antibody directed against H pylori (Dako a/s, Denmark, Lot # 111061). Stained sections were examined independently by two pathologists. All three staining methods failed to show H pylori in any of the cases examined. Sections of Barrett's esophagus (with and without dysplasia), adenocarcinoma, and stomach (when available) were uniformly negative for the presence of H pylori. We conclude that neither gastric nor esophageal infection with H pylori is a requisite for the development of adenocarcinoma in Barrett's esophagus. Moreover, it is unlikely that a significant association between H pylori infection and Barrett's-associated adenocarcinoma exists.

Normal gastric histology in Helicobacter pylori-infected children

BACKGROUND

In adults, Helicobacter pylori infection is always associated with gastritis or ulcer. However, very active gastritis and ulcers are rarely seen in children. The aim of the present work was to study the relationships between H. pylori and gastric mucosa in children.

METHODS

Eighty infected children and adolescents including 48 (60%) neurologically impaired institutionalized patients, aged 2 months-22 years (mean 11.7 +/- 5.2 years) were studied retrospectively. All the patients underwent gastroscopy, and three antral and two fundic biopsy specimens were taken for histology and bacteriology.

RESULTS

A normal gastric mucosa was found in 22 of 80 patients (27.5%), whereas the others had gastritis (n = 58, 72.5%). There were no statistical differences between patients with normal histology and those presenting with gastritis for age, sex, ethnic background, symptoms, and the degree of bacterial colonization. The macroscopic aspect of gastritis was less frequently found in children with a normal histology compared with those with histological gastritis (p < 0.001).

CONCLUSIONS

These data show that H. pylori infection can be associated with a normal gastric histology in children.

Helicobacter pylori duodenal colonization in children

To investigate the prevalence and the significance of Helicobacter pylori duodenal colonization, endoscopic duodenal biopsies were performed in 168 children with chronic abdominal pain, gastroesophageal reflux, gastrointestinal bleeding, and malabsorption syndrome. Helicobacter pylori infection was detected in 68 children (40.4%): in 31 of them H. pylori was present in the gastric antrum, and in 37 in the duodenum also. Duodenitis was observed in 25 children with duodenal H. pylori; gastric metaplasia in 3. Scanning electron microscopy revealed the presence of the micro-organism in 3/13 cases; the bacteria were located in the intercellular spaces and alterations of the epithelial surface were found. In conclusion, H. pylori gastritis in children is often associated with duodenal colonization which can cause duodenitis, and also without gastric metaplasia, which indicates a possible role of the micro-organism in the pathogenesis of the lesions.

The British Society of Gastroenterology Diamond Jubilee. March 1997

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Evaluation of Helicobacter pylori in reflux oesophagitis and Barrett's oesophagus

BACKGROUND

One of the major pathophysiological abnormalities in patients with gastro-oesophageal reflux disease is thought to involve transient lower oesophageal sphincter (LOS) relaxations. One component of the neural mechanism controlling the LOS appears to be a reflex are whose afferent limb originates in the gastric fundus. As inflammation is known to be associated with neural activation an investigation was made to determine whether gastric infection with H pylori is altered in prevalence or distribution in patients with reflux disease.

METHODS

Five groups of subjects referred for endoscopy-group 1: 25 controls (asymptomatic individuals with anaemia and normal endoscopy); group 2: 36 subjects with erosive oesophagitis alone (Savary-Millar grades I-III); group 3: 16 subjects with duodenal ulcer alone; group 4: 15 subjects with oesophagitis with duodenal ulcer; group 5: 16 subjects with Barrett's oesophagus. No patients were receiving acid suppressants or antibiotics. An antral biopsy specimen was taken for a rapid urease test, and two biopsy specimens were taken from the antrum, fundus, and oesophagus (inflamed and non-inflamed) for histological evidence of inflammation and presence of H pylori using a Giemsa stain.

RESULTS

Nine (36%) controls had H pylori. Patients with duodenal ulcer alone had a significantly higher incidence of colonisation by H pylori than other groups (duodenal ulcer 15 (94%); oesophagitis 13 (36%); oesophagitis+duodenal ulcer 6 (40%); Barrett's oesophagus 4 (25%)). H pylori was not more common in oesophagitis. When H pylori colonised the gastric antrum it was usually found in the gastric fundus. There was no difference in anatomical distribution of H pylori in the different patient groups. In Barrett's oesophagus H pylori was found in two of 16 in the metaplastic epithelium.

CONCLUSION

H pylori is not more common and its distribution does not differ in those with oesophagitis compared with control subjects, and is therefore unlikely to be aetiologically important in these patients. H pylori, however, can colonise Barrett's epithelium.

Immunohistochemical detection of Helicobacter pylori in the surface mucous gel layer and its clinicopathological significance

BACKGROUND

Attempts have been made to develop an accurate method for detecting Helicobacter pylori in histological sections.

MATERIALS AND METHODS

Biopsy specimens were obtained from the stomachs of 167 patients with gastric ulcer (33), duodenal ulcer (52), gastroduodenal ulcer (15), chronic gastritis (45), and normal mucosa (22) before antimicrobial treatment and from 108 of these patients after treatment. Biopsy specimens were (1) cultured, (2) fixed in 10% buffered formalin, or (3) fixed in Carnoy's solution. The latter method was employed to preserve the surface mucous gel layer (SMGL) covering gastric surface mucous cells. Histological sections were stained with hematoxylin and eosin (H&E), with immunostaining using a commercially available polyclonal anti-H. pylori antibody.

RESULTS

Cultures were positive for H. pylori in 61% of the cases before treatment and in 16% after treatment; by H&E staining using formalin-fixed materials: 70% and 9%; by immunostaining using formalin-fixed materials: 78% and 21%; and by immunostaining using Carnoy-fixed materials: 85% and 41% of biopsy specimens, respectively. The difference in detection rates between materials fixed in formalin and those in Carnoy's solution was due to the detection of H. pylori in the SMGL by the latter, especially after antimicrobial treatment.

CONCLUSIONS

Immunostaining for H. pylori using materials fixed in Carnoy's solution revealed H. pylori in the SMGL as well as on the surface mucous cells and in the gastric pits and permitted the optimal detection of H. pylori in tissue sections.

Histology of chronic gastritis with and without duodenitis in patients with Helicobacter pylori infection

AIM

To compare the histological characteristics of Helicobacter pylori positive chronic gastritis in patients with and without associated duodenitis.

METHODS

Gastric mucosal biopsy specimens were obtained from patients undergoing endoscopy for dyspepsia. Severity of gastritis and density of H pylori infection were graded according to the Sydney system.

RESULTS

Of the 69 patients studied, 15 had normal histology, 22 had chronic gastritis only (77.3% H pylori positive), 21 had duodenitis (90.5% H pylori positive), and 11 had other diagnoses. In the H pylori positive patients, the median gastritis score was higher in the duodenitis group (6, range 3-9) than in the chronic gastritis only group (5, range 2-8), because of greater neutrophil activity scores in patients with duodenitis (median score 2 v 1). There were no differences in the density of H pylori infection, inflammation, atrophy, or intestinal metaplasia between patients with chronic gastritis only and those with duodenitis.

CONCLUSIONS

These results suggest that H pylori positive patients with duodenitis have a more severe form of gastritis than those without associated duodenal inflammation. This is because of increased neutrophil activity, which seems to be independent of the density of H pylori infection.

Helicobacter pylori and peptic disease in the pediatric patient

The data accumulated on Helicobacter pylori infection in children suggests an important causative role of the organism in gastritis and peptic ulcer disease in this age group. The importance of eradication of H pylori in asymptomatic children in relation to its role in peptic disease and cancer in adults is debatable. This article describes the current data on bacteriologic features, pathologic spectrum, clinical significance, epidemiology, methods of diagnosis, and treatment of H pylori infection in children. Further studies will provide the information on the pathogenicity, mode of transfer, and optimal treatment of H pylori infection.

Prevalence of Helicobacter pylori in patients with gall stones before and after cholecystectomy: a longitudinal study

Fifty six patients with gall stones were enrolled in this study to assess the presence of Helicobacter pylori in gastric mucosa before and after cholecystectomy. Samples were taken from gastric juice and antral mucosa through endoscopy performed on these patients before and after the operation. Gastric juice was examined for bile salt concentration as an indicator of duodenogastric reflux. Antral mucosa was studied for the presence of H pylori and inflammatory response. Duodenogastric reflux was significantly increased (p < 0.001) and H pylori significantly decreased (p < 0.01) in the postoperative period. Mucosal inflammation and its activity were less in the postoperative period but the differences did not reach statistically significant values.

Pathophysiological effects of long-term acid suppression in man

A critical evaluation has been made of the available evidence in man of the effects of prolonged low acid states on the structure and function of the stomach. Various human models have been examined. 1. Ageing does not affect acid output from the normal male stomach, and there may be an increase in women. With progressive atrophy of the corpus mucosa, which is more frequent and rapid in patients with gastric ulcer, there is an associated loss of secretory function. Chronic gastritis and atrophy are the most important age-related changes, which in many cultures are hypothesized to develop via a prior Helicobacter pylori-related gastritis. However, H. pylori colonization of the mucosa decreases with increasing grades of gastric atrophy probably because intestinal metaplasia provides a hostile environment. Atrophy and intestinal metaplasia are associated with precancerous lesions and gastric cancer. Apparent hyperplasia of the gastric argyrophil endocrine cells is a common and spontaneous phenomenon in patients with atrophic gastritis, which in part may be related to the preferential loss of nonendocrine cells. 2. Pernicious anemia is associated with a complete lack of acid production, marked hypergastrinemia, and endocrine cell hyperplasia in the majority of patients. ECL-cell carcinoids and gastric cancer occur with a prevalence of 3-7%, and endoscopic surveillance in routine clinical practice is not warranted. 3. Gastric ECL-cell carcinoids are rare events that have been described in association with two diseases in man, pernicious anemia and Zollinger-Ellison syndrome as part of multiple endocrine neoplasia syndrome type I, and usually relate to marked hypergastrinemia and the presence of chronic atrophic gastritis with gastric antibodies or a genetic defect rather than the presence or absence of acid. Regression or disappearance of ECL-cell carcinoids, either spontaneously or after removal of the gastrin drive, has been recorded. Lymph node, and rarely hepatic, metastases are documented but death in these cases has been anecdotal. 4. Therapy with H2 antagonists may result in up to a twofold rise in serum gastrin levels but in man no endocrine cell hyperplasia has been recorded. However, the data for H2 antagonists on these aspects are very limited. There is no drug-related risk of gastric or esophageal cancer, although the incidence of the latter may be raised. Long-term treatment with omeprazole is associated with a two- to fourfold increase in gastrin levels over baseline values in one third of patients and apparent endocrine cell hyperplasia in 7% of cases overall.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of acid suppression on microbial flora of upper gut

Decreased acid secretion, due to therapy or disease, predisposes to increased bacterial counts in gastric juice. As bacterial numbers increase, the number of nitrate-reducing strains and the concentration of luminal nitrite usually also increase. However, there is controversy (mainly because of assay problems) about whether decreased acid increases generation of N-nitroso compounds: these may be produced by acid or by bacterial catalysis, and the relative contributions of each are still uncertain. Other potentially important factors include ascorbate secretion (can prevent nitrite conversion to nitroso compounds) and the particular spectrum of nitroso compounds produced. Nitrosation of several histamine H2-receptor antagonists has been demonstrated experimentally, but under conditions that are very unlikely to be encountered clinically. Some acid suppressant therapies have been claimed to aid eradication of Helicobacter pylori, but more work is needed to evaluate this. If ulcer treatment regimens do not also address eradication of H. pylori (when present), gastritis will progress, and the recently documented association between H. pylori and gastric carcinoma needs to be considered. Enteric flora probably also increase if acid secretion is markedly reduced: this does not appear to have nutritional consequences but probably reduces the resistance to occasional infections, of which cholera is the best documented.

Helicobacter pylori: the new bug on the (paraffin) block

A nameless spirillar organism in search of a disease only a few years ago, Helicobacter pylori has seen its fortunes suddenly reversed. After a rapid succession of name changes and some acrimonious disputes across continents, in less than a decade H. pylori has been catapulted to the centre stage of gastroenterological and microbiological research and has topped the most-wanted list of the pharmaceutical industry. The discovery of H. pylori has provided the momentum for the formation of the group that eventually created the Sydney System. Today, H. pylori is increasingly recognized as one of the most prevalent human pathogens worldwide. Its causal association with chronic active gastritis is undisputed and its role in the pathogenesis of peptide ulcer disease, although still poorly understood, is universally accepted. Furthermore, possible connections between chronic H. pylori infection and gastric carcinoma and primary gastric lymphoma are now being explored with increasing alacrity. With a few notable exceptions, pathologists have remained passive spectators of these exciting discoveries and have allowed gastroenterologists and microbiologists to set the pace in the quest for the determinants of gastritis, peptic ulcer and gastric cancer. This article is intended to outline some of the accepted facts on the development, progression, and pathology of H. pylori gastritis and to pose questions about this elusive infection. The authors hope that it might also contribute to stimulate further research, particularly on those aspects that are eminently suited to be addressed by pathologists.

Helicobacter pylori infection in north-eastern peninsular Malaysia. Evidence for an unusually low prevalence

The prevalence of Helicobacter pylori infection was determined in peptic ulcer patients, in non-ulcer dyspepsia (NUD) patients, and in the general adult population. The H. pylori infection rate ascertained by microbiologic examination of multiple gastric antral biopsy specimens was 50% (17 of 34) in duodenal ulcer (DU), 5% (1 of 22) in gastric ulcer, and 9% (15 of 159) in NUD patients. A seroepidemiologic survey showed a prevalence of only 4.2% among 496 blood donors and 4.8% among 921 subjects who attended health screening clinics. H. pylori infection is relatively uncommon and does not appear to be the predominant factor in the pathogenesis of peptic ulcer disease in the area. The incidence of peptic ulcer perforations in the area in 1991-92 was 1.5 per 100,000 person-years, reflecting a relatively low frequency of peptic ulcers, which might be due to the low prevalence of H. pylori infection in the population.

Phospholipase activity of Helicobacter pylori and its inhibition by bismuth salts. Biochemical and biophysical studies

In this study we measured phospholipase A (PLA) and C (PLC) activity of media filtrates and French Press lysates of the gastritis-inducing bacteria Helicobacter pylori. We report here that both H. pylori lysates and filtrates contain PLA1, PLA2, and C enzymes, which readily hydrolyze a radiolabeled dipalmitoylphosphatidylcholine (DPPC) and phosphorylcholine substrates, respectively. The specific activity of both PLA and C enzymes were greatest in the 6.5-7.0 and 8.4-8.8 pH ranges, respectively. Colloidal bismuth subcitrate (CBS) induced a dose-dependent inhibition of PLA2 and C activity of both H. pylori lysates and filtrates. This inhibitory effect of CBS on PLA2 was antagonized in a dose-dependent fashion by the addition of CaCl2 to the incubation mixture, suggesting that calcium and bismuth may be competing for the same site on the enzyme. In contrast, the ability of bismuth salts to inhibit PLC activity of H. pylori lysates was not antagonized by CaCl2. Employing a biophysical assay system for surface wettability, it was determined that H. pylori lysates had the capacity to remove a synthetic phospholipid monolayer off a glass in a dose-dependent fashion. This ability of the bacterial lysates to catalyze the transformation of a hydrophobic surface to a wettable state was significantly attenuated in the presence of bismuth salts. Our experimental results are, therefore, consistent with the possibility that H. pylori colonization compromises the stomach's barrier to acid by eroding a phospholipid lining, possibly a monolayer, on the surface of the gastric mucus gel and that this process is blocked in response to bismuth therapy.

Gastritis in patients on non-steroidal anti-inflammatory drugs

This study investigated the spectrum of gastric mucosal pathology, including the prevalence of reactive gastritis in patients on non-steroidal anti-inflammatory drugs (NSAIDs). The histological findings were correlated with upper gastrointestinal symptom status and endoscopic findings and were also compared with the histological appearances of the gastric mucosa in a corresponding age-matched control group of 75 patients not receiving NSAIDs or any other drug therapy. Reactive gastritis of the gastric antrum was more common in the NSAID group and was observed in 34 patients (45.3%), as an isolated phenomenon in 24 patients (32%) and with evidence of coexistent chronic gastritis in 10 patients (13.3%). In the control group reactive gastritis of the antrum was seen in 10 patients (13.3%), as an isolated finding in eight cases (10.7%) and with accompanying chronic gastritis in two cases. Chronic antral gastritis of usual type was observed in 36 patients on NSAIDs (48%) and Helicobacter-like organisms were identified histologically in 18 of these (50% carriage rate). These organisms were not seen in any of the patients in whom the picture of reactive gastritis was present. In the control group chronic antral gastritis was seen in 51 patients (68%) with organisms in 34 (66.6% carriage rate). No correlation was found between the presence or absence of upper gastrointestinal symptoms, endoscopic findings and the histological appearances of the gastric mucosa. We conclude that NSAIDs are an independent cause of reactive gastritis in the antrum and do not appear to alter gastric mucosal colonization by Helicobacter-like organisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric cancer and Helicobacter pylori infection

Gastric adenocarcinoma can be divided into two histopathological types: intestinal and diffuse. In addition to the role of environmental factors, an association between gastric cancer and Helicobacter pylori has been suggested. A retrospective study was therefore carried out among 46 patients who had gastric cancer. As a control group, 40 patients with non-malignant disorders were selected (11 patients with peptic ulcer, 12 with chronic superficial gastritis, 17 with chronic atrophic gastritis). Twenty-six cancers were classified as intestinal type and 20 as diffuse type. H. pylori was found in 23 (88 per cent) of the intestinal type and 11 (55 per cent) of the diffuse type (P < 0.05). Patients with the intestinal-type gastric cancer had a higher prevalence of H. pylori infection than those with gastric ulcer (55 per cent) and chronic superficial gastritis (50 per cent) (P < 0.05). These findings suggest that there is a possible association between the intestinal type of gastric cancer and H. pylori infection.

Role of Helicobacter pylori in the pathogenesis of gastritis, peptic ulcer and gastric cancer

Helicobacter pylori is the major causal factor in chronic gastritis. Its acquisition leads to a chronic, usually lifelong, inflammation of the gastric mucosa, which may gradually progress to atrophy (with intestinal metaplasia) in a significant proportion of infected individuals. This progression is probably multifactorial, being influenced by genetic or environmental factors in addition to H. pylori infection. The pathogenesis of peptic ulcer and gastric cancer is closely associated with H. pylori gastritis and its subsequent atrophic sequelae (atrophic gastritis). H. pylori-induced gastritis is an important risk factor in the multifactorial aetiology of these diseases. It causes a cascade of reactions that damage the gastric mucosa and epithelium in various ways. The specific mechanisms involved are largely unknown. Some are probably bacterium-related reactions, which are influenced by various virulence factors, and others are consequences of the mucosal inflammation and atrophy. The risk of peptic ulcer and gastric cancer in patients with H. pylori gastritis can be summarized as follows: i) the risk of both peptic ulcer and gastric cancer is low in individuals with a normal stomach; ii) the risk of peptic ulcer is approximately ten times higher and the risk of gastric cancer approximately twice as high in patients with non-atrophic H. pylori-positive gastritis as in those with a normal stomach; iii) these risks are further increased (twofold to threefold) when there is antral atrophy; whereas iv) in the presence of corpus atrophy the risk of gastric cancer remains high, but that of peptic ulcer decreases gradually to zero with increasing severity of corpus atrophy.

Activation of human phagocyte oxidative metabolism by Helicobacter pylori

A characteristic feature of chronic antral gastritis is the abundant inflammatory response in close association with Helicobacter pylori, but the immunopathological mechanisms of tissue damage are unknown. Because reactive oxygen radicals have been implicated in the tissue damage of other chronic inflammatory disorders, we investigated the potential ability of H. pylori sonicate to influence the oxidative burst responsiveness of human polymorphonuclear leukocytes and monocytes. For both cell types, a dose-dependent stimulation in a chemiluminescence system was observed. Furthermore, preincubation in sonicate caused a marked priming of the cells to subsequent stimulation with the oligopeptide N-f-methionyl-leucyl-phenylalanine and phorbol-myristate-acetate. The sonicate activity was nondialysable, completely destroyed by proteinase and resistant to heat treatment. However, dialysis of boiled sonicate significantly reduced the activity, suggesting the breakdown of a larger molecule(s) to smaller fragments still biologically active. Preliminary experiments suggest that the activity is 25-35 kilodaltons. The demonstration of a protein with stimulatory activity for production of reactive oxygen radicals by human phagocytes may contribute to the understanding of the immunopathology associated with H. pylori infection.

Helicobacter pylori. Its role in the pathogenesis of peptic ulcer disease in a new animal model

The association and causative role of Helicobacter pylori infection of the stomach with gastric ulcer, duodenal ulcer, non-ulcer dyspepsia, and gastritis has remained controversial. The authors studied the effects of daily intragastric administration of H. pylori suspension in saline (10(8) CFU/ml) and bacteria-free filtrates of saline H. pylori suspensions in 85 Sprague-Dawley rats (weight, 150 to 200 g) with normal mucosa and with surgically produced experimental gastric ulcers. Group I rats (n = 30) with pre-existent experimental gastric ulcers received H. pylori suspension (ATCC 43504, 10(8) CFU/ml); Group II rats (n = 20) with experimental gastric ulcers received bacteria-free H. pylori filtrates; Group III rats with ulcers (n = 20) received saline alone; and Group IV control rats (n = 15) without ulcers received intact H. pylori organisms in suspension (ATCC 43504, 10(8) CFU/ml). At death, ulcer surface areas were measured with a dissecting microscope. Full-thickness sections were obtained for quantitative and qualitative histologic parameters, including the area of remaining mucosal necrosis; characteristics and cellular composition of restored mucosal architectures; and presence or absence of inflammation including counts of neutrophils and lymphocytes. H. pylori organisms were identified within the surface mucus and crypts using routine, special, and immunohistochemical stains. Our results indicate that the continued presence of either intact H. pylori organisms or bacteria-free H. pylori filtrates in the stomachs of rats with pre-existent gastric ulcers resulted in delayed healing of the ulcers and persistence of chronic active inflammation. Daily administration of suspensions of H. pylori organisms to sham-operated rats with intact gastric mucosa, however, resulted in no ulceration or inflammation despite identification of surface H. pylori organisms at death. The authors conclude that H. pylori alone causes little or no effect on an intact gastric mucosa in the rat, that either intact organisms or bacteria-free filtrates cause similar prolongation and delayed healing of pre-existing ulcers with active chronic inflammation, and that the presence of predisposing factors leading to disruption of gastric mucosal integrity may be required for the H. pylori enhancement of inflammation and tissue damage in the stomach.

Difference in expression of Helicobacter pylori gastritis in antrum and body

Seven hundred seventy biopsy specimens obtained from 10 different sites in stomachs of 77 patients were examined for the presence of active chronic gastritis (ACG) and Helicobacter pylori to investigate the characteristics of gastritis in the antrum and body. Forty-eight patients with ACG at one or more sites were all H. pylori positive. H. pylori was not found in 20 patients who had chronic gastritis with no activity or in 9 patients who had histologically normal mucosa. In patients with ACG in at least one biopsy site, a strong positive topographic association between H. pylori colonization and ACG was seen in the Warthin-Starry stain. The frequency of H. pylori colonization was similar in the antrum and body. However, the incidence of ACG declined significantly proximal to the borderline between the antrum and body (P less than 0.001). The average grade of gastritis at the individual biopsy sites was distributed evenly throughout the antrum but decreased markedly in the body (P less than 0.0001). In the same manner, the average grade of H. pylori colonization decreased in the body (P less than 0.0027). The grade of H. pylori colonization in the individual biopsy specimens was closely related to the grade of gastritis (r = 0.51); also, the grade of neutrophil infiltration was related to the grade of gastritis (r = 0.79). A good correlation existed between the grade of H. pylori colonization and the grade of neutrophil infiltration (r = 0.70). The results of this study show a different expression of H. pylori gastritis in the antrum and body, which is the main subtype of chronic type B gastritis. The close topographic and graded association between the presence of H. pylori and the activity and grade of gastritis lend further support to the major pathogenic role of H. pylori in active chronic gastritis. The different expression of gastritis in antrum and body is suggested to be increased reactivity of the antral mucosa to the infection, possibly on the basis of an enhanced immunologic response to H. pylori in this region.

Ultrastructural study of Helicobacter pylori adherence properties in gnotobiotic piglets

Ultrastructural examination of gastric mucosa from Helicobacter pylori-infected gnotobiotic piglets identified four general adherence patterns comparable to those observed in human patients. Intimate associations between the bacterial and mucosal cell membranes, including cuplike invaginations and adherence pedestals, were present and were accompanied by alterations to microvilli and cell membrane morphology.

Longitudinal study of influence of Helicobacter pylori on current risk of duodenal ulcer relapse. The Hvidovre Ulcer Project Group

Seventy-four patients with duodenal ulcer were followed up longitudinally for 2 years after initial ulcer healing. Endoscopy including biopsy of the antral mucosa was performed every 3rd month and whenever clinical symptoms of relapse occurred. The presence of Helicobacter pylori in the biopsy specimens was scored as 0 (none), 1 (sporadic occurrence), 2 (clusters), and 3 (numerous bacteria found diffusely in the mucus layer). The incidence rates of ulcer relapse per patient-month, grouped in accordance with these scores, were (with 95% confidence intervals) 0.073 (0.048-0.111), 0.083 (0.052-0.133), 0.123 (0.096-0.157), and 0.069 (0.041-0.116), respectively. No significant differences in incidence rates across H. pylori scores were observed when taking into account the observation period after healing of the first ulcer, number of ulcer recurrence (1st, 2nd, 3rd), sex, age, smoking habits, peak acid output, time of healing of the preceding ulcer, treatment of the present ulcer (cimetidine, antacids, or no treatment), or type and degree of gastritis. Thus, although H. pylori is prevalent in patients with duodenal ulcer disease, the present study indicates that H. pylori does not have a substantial note in the precipitation of active duodenal ulcer.

Production of a conserved adhesin by the human gastroduodenal pathogen Helicobacter pylori

An adhesin protein with an approximate subunit molecular weight of 19,600 has been purified from the gastric pathogen Helicobacter pylori. The protein was loosely associated with the cell surface and was removed by gentle stirring or shearing. Released aggregates of the 19.6-kDa protein were removed from suspension by ultracentrifugation and separated from contaminating membranes by washing in 1.0% sodium dodecyl sulfate (SDS). The SDS-insoluble protein was purified further by Mono Q anion-exchange column chromatography. Electron microscopy of the purified adhesin demonstrated that it formed amorphous aggregates similar to the material attached to the bacterial cells and that the aggregates were morphologically distinct from typical fimbriae. Western blot (immunoblot) analysis with antiserum raised against the purified protein from one strain reacted with a protein with a similar subunit molecular weight present in all nine strains of H. pylori examined, but the protein was not present in other Helicobacter species examined. The N-terminal sequences of the 19.6-kDa protein purified from three different strains of H. pylori were identical for the first 28 amino acids, with the 10 amino-terminal residues showing limited sequence homology with the TcpA pilus protein of Vibrio cholerae. The H. pylori 19.6-kDa protein associated both with human and rabbit erythrocytes and with human buccal epithelial cells. Polystyrene microspheres coated with the protein agglutinated human, horse, and rabbit erythrocytes, suggesting that this protein species could mediate adhesion between H. pylori and eucaryotic cells. This ability to act as an adhesin may make this protein an important virulence factor for H. pylori and hence a potential target for a vaccine and therapy.

Beta-2-microglobulin and Helicobacter pylori infection in uraemic dialysed patients

Chronic gastritis in patients with chronic renal failure may have different causes and mechanisms. Recent observations suggest that severe gastritis often found in uraemic patients might be related to Helicobacter pylori (HP) infection. In chronic gastritis HP has been found in the mucus and on the epithelial cell surface of gastric foveolas. Significant infiltration of the subepithelial gastric layer by polymorphonuclear leucocytes has been described. Moreover, beta-2-microglobulin deposits have been found by immunohistochemical methods in the subepithelial layer of gastric mucosa of uraemic dialysed patients with active chronic gastritis and HP infection. Similar findings have also been demonstrated in gastric biopsies from patients with HP positive active chronic gastritis and normal renal function. Since HP infection is associated with significant leucocyte infiltration, it is hypothesized that the inflammatory process causes the release of beta-2-M from the surface of the leucocytes and its subsequent deposition at gastric level.

A comparison of diagnostic tests to determine Helicobacter pylori infection

Twenty-five Helicobacter pylori positive and 25 H. pylori negative subjects as defined by culture and phase contrast microscopy of antral biopsy specimens obtained from routine upper endoscopy were studied. Antral biopsies were examined by rapid urease test, phase contrast microscopy, culture and histology. Venous blood was tested for H. pylori specific IgG antibodies by an ELISA technique. Within 7 days of endoscopy the patients also had a [14C]-urea breath test. The sensitivity and specificity of the rapid urease test was 92%, the breath test 96% and 100%, histopathology 96% and 91% and serology 96% and 88%, respectively. The [14C]-urea breath test performed over 1 h with sampling of subjects at 0, 0.5 and 1 h was an accurate and reliable method. Results expressed as counts per minute of the expired 14CO2 proved to be a simple method of assessing H. pylori status. A significant correlation between severity of histological antral gastritis and the amount of 14CO2 expired was observed. This study has shown that the non-invasive 14C-urea breath test and serology are highly sensitive and specific for the diagnosis of H. pylori infection.

Chemical gastritis and Helicobacter pylori related gastritis in patients receiving non-steroidal anti-inflammatory drugs: comparison and correlation with peptic ulceration

AIMS

To evaluate the prevalence and significance of chemical gastritis, in comparison with gastritis related to Helicobacter pylori in patients receiving non-steroidal anti inflammatory drugs (NSAIDs).

METHODS

Two hundred and eighteen patients were studied, 174 of whom were taking NSAIDs. Chemical gastritis was defined as the presence of foveolar hyperplasia, muscle fibres in the lamina propria, oedema and vasodilation, in the absence of a chronic inflammatory cell infiltrate.

RESULTS

Chemical gastritis was found in 46 (26%) patients taking NSAIDs, and three (7%) in subjects not taking these drugs (p less than 0.01). H pylori was detected in 56 (32%) subjects taking NSAIDs compared with 22 (50%) not taking these agents (p less than 0.02). Ulcers were found in 16 out of 72 patients (22%) taking NSAIDs and without H pylori infection or chemical gastritis compared with 27 out of 56 (48%) with H pylori related gastritis (p less than 0.01), and 25 out of 46 (54%) with chemical gastritis (p less than 0.01).

CONCLUSIONS

Peptic ulcers associated with the use of NSAIDs seem to occur more commonly in patients with chemical gastritis or H pylori infection. Patients taking NSAIDs also seem to have a greater prevalence of chemical gastritis but a lower prevalence of H pylori than those not taking these drugs.

Helicobacter pylori: past, present, and future

Helicobacter pylori has now been recognized as one of the most common chronic human infections. It has been accepted as an important aetiologic agent in non-immune chronic gastritis and plays a key role in the aetiology of duodenal ulcer. It may also be involved in the pathogenesis of gastric cancer.

Association of Helicobacter pylori and nonulcer dyspepsia

The etiology and pathogenesis of nonulcer dyspepsia (NUD) are not completely understood and consequently, no specific medication can be prescribed to the sufferers. We studied 69 cases, proved clinically, laboratorally, sonographically and endoscopically, to have NUD. Antral biopsy was taken from every case and subjected to CLO test. Out of the 69 patients, 51 (74%) were infected with Helicobacter pylori (HP). Oral medication, consisting of amoxacillin 500 mg, metronidazol 500 mg, and bismuth mixture, 5 mls three times daily was prescribed for four weeks. Out of the 51 patients at the end of four weeks, 46 cases (90%) were cleared of HP, and only 38 cases (74.5%) experienced complete improvement of their dyspeptic symptoms. We arrived at the conclusion that a good percentage of NUD patients can be cured by the use of the 3-drug combination.

Intestinal metaplasia and Helicobacter pylori: an endoscopic bioptic study of the gastric antrum

To study the relationship between intestinal metaplasia and Helicobacter pylori infection, 2274 gastroscopic antral biopsies taken from 533 patients were examined. Overall, intestinal metaplasia was found in 135 patients (25.3%) and H pylori in 289 patients (54.2%). The prevalence of intestinal metaplasia and H pylori was age related, being more common in patients greater than or equal to 50 years compared with patients less than 50 years (intestinal metaplasia, p less than 0.001 and H pylori, p less than 0.05). Intestinal metaplasia was found more often in H pylori positive patients compared with H pylori negative patients (33.9% v 15.2%, p less than 0.001). The mean age of intestinal metaplasia positive patients who were also H pylori positive was 64 (13.3) years, whereas the mean age of intestinal metaplasia positive patients who were H pylori negative was 72 (14.7) years (p less than 0.005). The extent of intestinal metaplasia was not statistically different in the latter two groups. Although our data do not prove a causal relationship between H pylori infection and the histogenesis of intestinal metaplasia it is suggested that H pylori infection is an important factor in the development of intestinal metaplasia, which is generally recognised as a precursor lesion of intestinal type gastric carcinoma.

Is Helicobacter pylori a cause of duodenal ulcer? A methodologic critique of current evidence

INTRODUCTION

Helicobacter pylori (HP) in the gastric antrum has been strongly associated with both duodenal ulcer (DU) and chronic active gastritis (CAG). The relationship between HP and DU has been interpreted as causal by many observers. An alternate hypothesis is that HP coincidently colonizes CAG, which is independently associated with DU by some yet-unknown mechanism.

PURPOSE

To assess the extent to which a causal relationship between HP and DU has been demonstrated, we performed a methodologic critique of published clinical studies. We carried out a literature search to identify clinical studies that included at least 25 subjects. Of the eight studies we identified, six used a cross-sectional design and two used a prospective cohort design. We applied methodologic criteria to assess causation: strength of association, biologic gradient, temporality, and experiment.

METHODS

A strong association between HP and DU was demonstrated in all eight studies. Biologic gradient and temporality were not assessed in any study. In the two experimental studies of therapy, loss of antral HP was associated with a decreased rate of DU relapse; however, we did not interpret this as sufficient to support causality because the effect may have been due to a direct mucosal action rather than eradication of HP.

CONCLUSION

We conclude that published evidence does not establish HP as a cause of DU. One approach to address causality would be an observational cohort study of ulcer relapse to assess the temporal relationships between HP, CAG, and DU.