Helicobacter pylori and ulcerogenesis

Indistinguishable cellular changes in gastric mucosa between Helicobacter pylori infected asymptomatic tribal and duodenal ulcer patients

AIM

To investigate the changing pattern of different histological parameters occurring in the stomach tissue of Helicobacter pylori (H pylori) infected tribal populations and duodenal ulcer patients among ethnic Bengalis and correlation of the genotypes of H pylori with different histological parameters.

METHODS

One hundred and twelve adult individuals were enrolled into this study between 2002 and 2004. Among them, 72 had clinical features of duodenal ulcer (DU) from ethnic Bengali population and 40 were asymptomatic ethnic tribals. Endoscopic gastric biopsy samples were processed for histology, genotyping and rapid urease test. Histologically, haematoxylin and eosin staining was applied to assess the pathomorphological changes and a modified Giemsa staining was used for better detection of H pylori. For intestinal metaplasia, special stainings, i.e. Alcian blue periodic acid-Schiff and high iron diamine-Alcian blue staining, were performed. PCR was performed on bacterial DNA to characterize the presence or absence of virulence-associated genes, like cagA, and distribution of different alleles of vacA and iceA.

RESULTS

Intraglandular neutrophil infiltration, a hallmark of activity of gastritis, was present in 34 (94%) of tribals (TRs) and 42 (84%) of DU individuals infected with H pylori. Lymphoid follicles and aggregates, which are important landmarks in H pylori infection, were positive amongst 15 (41%) of TRs and 20 (40%) of DU subjects. Atrophic changes were observed in 60% and 27.7%, respectively, among DU cases and tribals (P > 0.003). Metaplastic changes were detected in low numbers in both groups. Moderate to severe density distribution of H pylori in the gastric mucosa was 63% among TRs, whereas it was 62% in DU subjects. There were no significant differences in the distribution of virulence-associated genes like cagA, vacA and iceA of H pylori strains carried by these two populations.

CONCLUSION

Our study showed almost similar distribution of inflammatory cells among asymptomatic tribals and DU Bengali patients. Interestingly, the tribal population are free from any clinical symptoms despite evidence of active histologic gastritis and infection with H pylori strains carrying similar virulence markers as of strains isolated from patients with DU. There was an increased cellular response, especially in terms of neutrophil infiltration, but much lower risk of developing atrophy and metaplastic changes among the tribal population.

Mixed infections of Helicobacter pylori: tissue tropism and histological significance

Mixed infections with Helicobacter pylori facilitate interstrain gene transfer and the maintenance of genetic diversity for adaptation to the gastric environment, but whether mixed infections with histological significance and tissue tropism occur in the human stomach is still unclear. Helicobacter pylori was isolated from the antrum and the corpus of 30 dyspeptic patients. Four to eight colonies were randomly collected from each site. The genetic diversity of each isolate was evaluated by comparing random amplified polymorphic DNA banding patterns. The prevalence of mixed infections was 23.3% (7/30), and different dominant strains were isolated from the antrum and the corpus specimens. In the 23 patients infected with a single strain, the acute inflammation (AI) score, chronic inflammation (CI) score, atrophy (AT) score and lymphoid follicle (LF) score of the antrum were usually higher than those of the corpus (p <or=0.002). However, in the seven patients with mixed infections, the CI, H. pylori density (HPD), AT and LF scores of the antrum and the corpus were similar (p >0.05). Moreover, the patients with mixed infections had marginally higher CI and HPD scores than those with single-strain infection (p 0.062 and p 0.095, respectively) in the corpus and had a significantly higher rate of appearance of intestinal metaplasia (IM) in the antrum (p 0.005). These data show that H. pylori tissue tropism was found in the human stomach, and suggest that mixed infections could change the histological features in the antrum and in the corpus, and that they could be associated with the appearance of IM in the antrum.

Diagnosis of Helicobacter pylori: improving the sensitivity of CLOtest by increasing the number of gastric antral biopsies

BACKGROUND AND GOAL

The rapid urease CLOtest is commonly used during endoscopy to diagnose the presence of Helicobacter pylori. The aim of this study was to determine whether the sensitivity of the CLOtest can be improved by increasing the number of gastric antral biopsies from 1 to 4.

METHODS

The study included 100 adult patients who were referred for upper gastrointestinal endoscopy and tested positive for H. pylori infection on C urea breath test ("gold standard"). These 100 patients were then randomly divided into 4 equal groups (groups 1 to 4), and underwent an upper gastrointestinal endoscopy. Patients in group 1 had 1 gastric antral biopsy during endoscopy, whereas those in groups 2, 3, and 4 had 2, 3, and 4 biopsies, respectively. The biopsies were placed in the rapid urease CLOtests, which were incubated at room temperature for up to 24 hours, and read for positive results at 1, 6, and 24 hours.

RESULTS

About half of the patients (52%) had a positive CLOtest in group 1, compared to 68% in group 2, 76% in group 3, and 96% in group 4 (group 1 vs. 4 P<0.01). After 1 hour of incubation 96% of the patients in group 4 had a positive CLOtest, compared to 40% in group 3, 12% in group 2, and 4% in group 1.

CONCLUSIONS

Increasing the number of gastric antral biopsies from 1 to 4 significantly improves the sensitivity of the CLOtest, eliminates sampling error, and hastens the time needed by the test to become positive for the diagnosis of H. pylori infection.

Helicobacter pylori in areas of gastric metaplasia in the gallbladder and isolation of H. pylori DNA from gallstones

AIMS

To assess if the areas of gastric metaplasia in the gallbladder are colonised by Helicobacter pylori and to conduct a molecular study of gallstones for presence of H. pylori DNA.

METHODS

Sections from 111 gallbladders with evidence of gastric metaplasia on H&E and Alcian blue-periodic acid-Schiff (pH 2.5) stain were stained with Loeffler's methylene blue and Warthin Starry stain for demonstration of H. pylori. Presence of H. pylori was confirmed by immunohistochemistry. Formalin fixed mucosal tissues and gallstones from 11 cases showing heavy colonisation were subjected to molecular analysis.

RESULTS

Helicobacter pylori was present in 50 of 111 (45%) sections with gastric metaplasia. Areas adjacent to gastric metaplasia in gallbladder showed acute inflammation (6%) and lymphoid follicle formation in 58% of cases with H. pylori that were significantly higher than those seen in sections without H. pylori. In molecular study, 8 of 11 gallstones showed 16S rDNA. Amplification of material from one stone showed positivity for atpA, efp, mutY, ppa, trpC, UreI and vacA genes. Phylogenetic affiliation study of the isolates indicated that H. pylori sequence from the gallstones clustered with Indian strains of H. pylori. No considerable difference was observed in phylogenetic affiliations of eight stones studied.

CONCLUSION

H. pylori colonises areas of gastric metaplasia in gallbladder producing histological changes similar to those seen in gastric mucosa. Isolation of H. pylori DNA from gallstones further support its presence in the gallbladder.

Phosphorylation of Helicobacter pylori CagA in patients with gastric ulcer and gastritis

The effects of Helicobacter pylori infection are strongly associated with chronic gastritis, gastric and duodenal ulcer, gastric cancer, and MALT lymphoma. The microorganism has been classified as a type I carcinogen by the World Health Organization. Varying clinical results from H. pylori infection are believed due, in part, to differences in virulence among species. The cag pathogenicity island is a complex of virulent genes and a coding region for the type IV phosphorylated secretion system. Through this system, many virulent gene products or proteins are phosphorylated into the host cells. This study demonstrated the positive CagA-phosphorylation effect of H. pylori in patients with chronic gastritis and benign gastric ulcer and revealed significantly different rates of CagA phosphorylation between these two diseases (P<.05).

Environmental cues and gene expression in Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans

Microorganisms typically adapt to environmental cues by turning on and off the expression of virulence genes which, in turn, allows for optimal growth and survival within different environmental niches. This adaptation strategy includes sensing and responding to changes in nutrients, pH, temperature, oxygen tension, redox potential, microbial flora, and osmolarity. For a bacterium to adhere to, penetrate, replicate in, and colonize host cells, it is critical that virulence genes are expressed during certain periods of the infection process. Thus, throughout the different stages of an infection, different sets of virulence factors are turned on and off in response to different environmental signals, allowing the bacterium to effectively adapt to its varying niche. In this review, we focus on the regulation of virulence gene expression in two pathogens which have been implicated as major etiological agents in adult and juvenile periodontal diseases: Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans. Understanding the mechanisms of virulence gene expression in response to the local environment of the host will provide crucial information in the development of effective treatments targeted at eradication of these periodontal disease pathogens.

High prevalence of mixed infections by Helicobacter pylori in Hong Kong: metronidazole sensitivity and overall genotype

BACKGROUND

Diversity in metronidazole susceptibility and genotypes of Helicobacter pylori have been reported with varying results in different areas.

AIMS

To investigate the prevalence of multiple strain infection in a symptomatic Chinese population and to determine the metronidazole susceptibility pattern and genotypic characteristics of these infecting strains.

METHODS

Gastric biopsies from antrum, body and cardia were taken during upper endoscopy in symptomatic patients referred to our department. Pooled cultures and single colony isolates were obtained and tested for metronidazole susceptibility and random amplified polymorphic DNA (RAPD) fingerprint patterns.

RESULTS

A total of 461 isolates were successfully cultured from 46 patients. Fifty-seven per cent of subjects had metronidazole-resistant strains. Among them, 77% carried a mixture of sensitive and resistant strains, non-uniformly distributed in the gastric mucosa. Mixed genotypes were found by RAPD typing in 24% of subjects. These did not correlate with the metronidazole susceptibility/resistance pattern.

CONCLUSION

H. pylori infections with mixed metronidazole sensitive/resistant strains and mixed genotypes are common in Hong Kong. This makes it prudent to use bacterial strains from several biopsy sites when testing for traits such as drug resistance or virulence in relation to disease.

Consensus and variable region PCR analysis of Helicobacter pylori 3' region of cagA gene in isolates from individuals with or without peptic ulcer

The clinical outcome of Helicobacter pylori infection may be associated with the cagA bacterial genotype. To investigate the cagA status of H. pylori-infected patients and the relationship between cagA and peptic ulcer disease, gastric biopsy specimens from 103 Caucasian patients in Brazil were analyzed by PCR. Since allelic variation in cagA exists and distinct H. pylori subgenotypes may circulate in different regions, PCR using primers for a variable 3' region of the cagA gene according to a Japanese methodology and for a consensus cagA 3' region used in Western methods was used for cagA detection. cagA was present in 53 (71%) of 75 H. pylori-positive cases when analyzed by the consensus region method and was associated with duodenal ulcer disease (P = 0.02), but not with gastric ulcer (P = 0.26), when compared to patients with duodenitis or gastritis. The variable region PCR method was able to detect 43 (57%) cagA-positive cases within the same group of H. pylori-positive patients and showed three subtypes of cagA (A, B/D, and C) that were not associated with clinical outcome. However, in 8 (18%) of the cases, more than one subtype was present, and an association between patients with multiple subtypes and disease outcome was observed when compared to patients with isolated subtypes (P = 0.048). cagA was a marker of H. pylori strains for duodenal ulcer disease in our population, and in spite of the differences in the 3' region of the cagA gene, the Japanese methodology was able to detect the cagA status in most cases. The presence of multiple subgenotypes of cagA was associated with gastric ulcer.

A topographic study of Helicobacter pylori density, distribution and associated gastritis

BACKGROUND AND AIMS

The topographic distribution and density of Helicobacter pylori and associated gastritis in the stomach were studied in order to determine which biopsy sites are likely to provide the maximum yield so as to reduce the fallacious results due to sampling error.

METHODS

Fifty patients with upper gastrointestinal symptoms were studied. Eleven gastric biopsies from predetermined sites were obtained and subjected to ultra-rapid urease test, imprint cytology and histology. Haematoxylin and eosin stain was used for defining gastritis and other associated histopathological details. Loeffler's methylene blue stain was used to confirm the presence of H. pylori in imprint smears and histological sections.

RESULTS

All 50 patients had H. pylori infection and evidence of chronic gastritis at one or more of the 11 biopsy sites. Maximum and minimum percentage positivity were observed at A3 (antral lesser curvature) and B4 (corpus greater curvature), respectively. Various sites in decreasing order of percentage positivity were A3 > A2 > A1 > A4 > B3 > B1 > A5 > B6 > B5 > B2 > B4. Among the biopsies obtained from the corpus, B3 (corpus lesser curvature) was the site with maximum positivity. A3 and B4 had a statistically significant difference in percentage positivity (P < 0.0001) for H. pylori and gastritis. The maximum and minimum density scores of H. pylori and gastritis were found in A3 and the B4, respectively. A3 had a significantly higher (P < 0.0001) mean density score than any other site in the stomach. The difference in the grading of H. pylori between A3 and B3 (sites of maximum positivity in antrum and corpus) was statistically significant (P < 0.0001). A statistically significant (P < 0.001) positive correlation between increasing grades of H. pylori and gastritis was observed at the site of maximum density. Eighty per cent of the patients had antral predominant gastritis and in 82%, H. pylori was predominantly observed in antral biopsies.

CONCLUSION

It is concluded that two biopsies taken from A3 are sufficient for confirmation of presence of H. pylori and associated gastritis for initiation of treatment. However, additional biopsies from B3 will help in deciding the topographic pattern of gastritis.

Diagnosis and management of Helicobacter pylori infection

Helicobacter pylori infects more than half of the world's population, making it one of the most prevalent infections. H pylori is now accepted as the most common cause of histologic gastritis and is responsible for the majority of cases of peptic ulcer disease and gastric cancer. Approximately 1 in 6 (17%) persons with H pylori infection will develop peptic ulcer disease, and each year 1% to 2% of these will experience a major or life-threatening complication, such as bleeding, perforation, or gastric outlet obstruction. Peptic ulcer disease should no longer be regarded as a chronic, recurring, lifelong disease, but rather as a curable infectious disease. The diagnosis and therapy of this common infectious disorder have become increasingly straightforward. In this article, we discuss the possible outcomes of long-standing infection, the various diagnostic tests available, including whom and when to test, and the combination drug regimens approved for cure.

Eradication ofHelicobacter pylori in the Treatment of Peptic Ulcer Disease

Helicobacter pylori is responsible for the majority of cases of peptic ulcer disease. Peptic ulcer disease should no longer be regarded as a “chronic, recurring, lifelong disease, but rather a curable infection.” Treatment and eradication of H. pylori infection in patients with peptic ulcer disease has been shown to resolve the chronic inflammation present and prevent further ulcer relapse. Despite the vast amount of literature on H. pylori infection in peptic ulcer disease, the diagnosis and management of this common infection have become increasingly straightforward. This article will summarize the role of H. pylori in patients with peptic ulcer disease and will address the current clinical practice guidelines for diagnosis and treatment of H. pylori in the subset of patients.

The relationship between Helicobacter pylori infection and acid-hematuria syndrome in pediatric patients with gastric augmentation-II

BACKGROUND/PURPOSE

The acid-hematuria syndrome, which presents with dysuria, hematuria, and perineal pain still remains a problem in those patients who have undergone bladder augmentation using the gastrocystoplasty technique. Additionally, there is still a question regarding the explanation for postoperative metabolic problems such as metabolic alkalosis, hypocholoremia, hypergastrinemia, and various complications related to gastritis and peptic ulcer disease. The aim of this study was to investigate the relation of Helicobacter pylori (HP) infection in this patient group and the relationship between HP infection and the above-mentioned clinical problems and complications.

METHODS

In this study, 10 children with a history of previous gastrocystoplasty (five girls, five boys; mean age, 6.75+/-2.53 years; range, 2.5 to 12 years) were evaluated. Blood samples for HP detection were analyzed by serological testing (ELISA technique). Histopathologic studies were performed for gastric tissue specimens, obtained by endoscopic procedures from the stomach and augmented bladder. Urine pH and serum gastrin levels were measured in all patients.

RESULTS

Regarding the serological studies, four of ten patients had a positive ELISA test result (40%). The four patients with HP-positive serological test results, were the patients who had acid-hematuria syndrome. These patients also had low urine pH levels (mean, 4.5) when compared with those of HP-negative patients. HP-positive patients also had high serum gastrin levels in comparison with those of HP-negative patients.

CONCLUSIONS

The relation between HP infection and problems such as hypergastrinemia, acid output, and ulcer disease is well known. Our study demonstrates a correlation between the HP-positive gastrocystoplasty patients and the above-mentioned symptoms and complications. Because of the potential risk of HP infection, we suggest that HP infection be investigated in patients with gastrocystoplasty or in candidates for a gastrocystoplasty operation. HP-positive patients should be treated, to reduce the risks of postoperative complications.

Scope and consequences of peptic ulcer disease. How important is asymptomatic Helicobacter pylori infection?

H pylori infection is so common as to seem ubiquitous in many areas of the world. Transmission is believed to be primarily person to person. The pathogen invariably damages the gastric mucosa, resulting in both structural and functional abnormalities. It causes histologic gastritis and is critical in the pathogenesis of the gastritis-associated diseases, namely, gastric ulcer, duodenal ulcer, gastric adenocarcinoma, and primary gastric lymphoma. Elimination of the infection results in healing of gastritis and cure of peptic ulcer disease.

Effect of ranitidine on the urea breath test: a controlled trial

Because Helicobacter pylori is an acid-sensitive organism, an elevation of the gastric pH by H2 inhibitors might improve the intragastric conditions for the development of this organism. We tested this hypothesis in a prospective and controlled trial including 43 patients positive for H. pylori using the rapid urease test. Twenty-six patients received 150 mg ranitidine twice daily and 17 patients received no treatment. The 14C-urea breath test was performed in both groups at the beginning of the study and 2 weeks later. Radioactive 14C in exhaled carbon dioxide was significantly increased (p = 0.045) in the patients treated with ranitidine, compared with the patients in the control group. Administration of this drug to patients infected with H. pylori is associated with an increase in the bacterial load after 2 weeks of treatment. This phenomenon might be attributed to increased bacterial growth due to the H2 blocker.

The G cell

The study of gastrin continues to serve as an excellent model for gastrointestinal regulatory processes. This review highlights some recent advances in the field by outlining gastrin biosynthesis, summarizing current understanding of gastrin receptors, describing the regulation of gastrin release, and discussing the clinical implications of gastrin in the pathogenesis of peptic ulcer disease. Emphasis is on three emerging areas of gastrin research: the novel finding that one of gastrin's posttranslational processing intermediates has biological activity distinct from that of the mature peptide; elucidation of gastrin's signal transduction mechanisms that mediate the trophic effects of the peptide; and the role of gastrin in peptic ulcer disease pathogenesis secondary to Helicobacter pylori infection.

The fascinating complexities of steroid-binding enzymes

Enzymes that modulate the level of circulating steroid hormone can be used to combat steroid-dependent disorders. Members of the NADPH-dependent short chain dehydrogenase/reductase (SDR) family control blood pressure, fertility, and natural and neoplastic growth. Despite the fact that only one amino acid residue is strictly conserved in the 60 known members of the family, all appear to have the dinucleotide-binding Rossmann fold and homologous catalytic residues containing the conserved tyrosine. Variation in the amino acid composition of the substrate binding pocket creates specificity of binding for steroids, prostaglandins, sugars and alcohols. Licorice induces high blood pressure by inhibiting an SDR in the kidney, and appears to combat ulcers by inhibiting another in the stomach. Detailed X-ray analyses of various members of the family should allow the design of potent, tissue-specific, highly selective inhibitors.