Detection of Helicobacter pylori virulence-associated genes

Detection of Helicobacter Pylori by PCR on Gastric Biopsy Specimens Taken for CP Test: Comparison with Histopathological Analysis

The aims of the present study were: (i) to assess whether H. pylori could be succesfully detected by PCR from the same biopsy sample used for CPtest; and ii) to evaluate CPtest comparatively to both PCR and histology for detection of H. pylori infection in dyspeptic patients. Three antral gastric biopsies were collected from each of 80 consecutive dyspeptic patients undergoing oesophagogastroduodenoscopy. Two biopsies were for histology (gold standard), one for CPtest, scored at 20min, 1h and 24h for the presence of urease activity. Gastric biopsy was then removed from CPtest and used for ureC-targeted PCR. Fifty-five (68.7%) patients were positive for H. pylori infection by histology. CPtest yielded an overall diagnostic accuracy of 93.8% (95% CI: 91–96.4%), regardless of observation period. No erroneous categorization of H. pylori status occurred using PCR, yielding sensitivity, specificity, positive and negative predictive values, and overall diagnostic accuracy of 100%. Our results suggest that H. pylori can be detected by PCR in gastric biopsies previously taken for CPtest, so reducing the workload of the endoscopist by saving additional biopsies for culture analysis and susceptibility tests.

Activation of Helicobacter Pylori Causes Either Autoimmune Thyroid Diseases or Carcinogenesis in the Digestive Tract

Helicobacter pylori has been implicated in stimulation of immune system, development of autoimmune endocrinopathies as autoimmune thyroiditis (AT) and on other hand induction of immunosupresion activates gastric and extra-gastric diseases such as gastric ulcer or cancer. It causes persistent lifelong infection despite local and systemic immune response. Our results indicate that Helicobacter pylori might cause inhibition of the specific cellular immune response in Helicobacter pylori-infected patients with or without autoimmune diseases such as AT. We cannot also declare the carcinogenic effect in oropharynx. However the association of any infection agents and cancerogenesis exists. The adherence of Helicobacter pylori expression and enlargement of benign lymphatic tissue and the high incidence of the DNA of Helicobacter pylori in laryngopharyngeal and oropharyngeal cancer is reality. LTT appears to be a good tool for detection of immune memory cellular response in patients with Helicobacter pylori infection and AT. All these complications of Helicobacter pylori infection can be abrogated by successful eradication of Helicobacter pylori.

An overview of history, pathogenesis and treatment of perforated peptic ulcer disease with evaluation of prognostic scoring in adults

Peptic ulcer disease including both gastric and duodenal ulcer form a substantial part of patients seeking surgical opinion world-wide. The concept of acid in peptic ulcer disease, which was the basis of treatment of peptic ulcer was revolutionized by the discovery of H₂-receptor antagonists, that led to the principle of acid suppression therapy for duodenal ulcer which followed decades of preference for surgical interventions in the form of gastric resections, vagotomy etc., After the discovery of Helicobacter pylori organism as the causative factor a triple drug regime was identified to treat peptic disease which was further modified to sequential therapy to avoid antibiotic resistance. This recognition has not concluded the chapter on peptic ulcers. The management of ulcer disease and its complications remain a surgical challenge. All the materials for this review have been accessed from various internet search engines. The references have been narrowed down to 34 by excluding cross references, duplicated citations, pediatric studies, case reports, iatrogenic and malignant perforations and including microbiological, immunohistochemistry references and studies with more than a sample size of ten. Case control, cohort studies, prospective/retrospective, metaanalytical studies were preferred in that order. This article attempts to take an overview of all aspects of the management of peptic ulcer.

Evaluation of Helicobacter pylori vacA genotypes in Iranian patients with peptic ulcer disease

Helicobacter pylori is the major cause of active chronic gastritis and peptic ulcers in humans and has been linked to gastric carcinoma and lymphoma. The vacuolating cytotoxin vacA and cag pathogenicity island (cag PAI) are two identified virulence factors that are considered to have an important role in the pathogenesis of H. pylori infection. The aim of this study is to investigate the H. pylori vacA alleles in Iranian patients with peptic ulcer disease. In order to investigate this, biopsy specimens were obtained from 84 patients with gastric ulcer, gastritis, and duodenal ulcer. DNA extraction and PCR were used to detect the presence or absence of glmM, cagA and to assess the polymorphism of vacA. Of the 77 glmM PCR-positive biopsy specimens, 55 (71%) had the vacA signal sequence genotype s1, and 22 (29%) had subtype s2. vacA mid-region analysis revealed that 31 (40%) were vacA m1 and 46 (60%) were m2. The presence of the cagA gene correlated with vacA signal sequence type s1, whereas type s2 was predominantly found in cagA-negative samples (P < 0.001). Thus, the detection of vacA and cagA, virulence markers described in several clinical outcomes may be used to help the treatment and prevention of H. pylori in Iran.

Helicobacter genotyping and detection in peroperative lavage fluid in patients with perforated peptic ulcer

INTRODUCTION AND OBJECTIVES

Certain Helicobacter pylori genotypes are associated with peptic ulcer disease; however, little is known about associations between the H. pylori genotype and perforated peptic ulcer (PPU). The primary aim of this study was to evaluate which genotypes are present in patients with PPU and which genotype is dominant in this population. The secondary aim was to study the possibility of determining the H. pylori status in a way other than by biopsy.

MATERIALS AND METHODS

Serum samples, gastric tissue biopsies, lavage fluid, and fluid from the nasogastric tube were collected from patients operated upon for PPU. By means of PCR, DEIA, and LIPA the presence of the "cytotoxin associated gene" (cagA) and the genotype of the "vacuolating cytotoxin gene" were determined.

RESULTS

Fluid from the nasogastric tube was obtained from 25 patients, lavage fluid from 26 patients, serum samples from 20 patients and biopsies from 18 patients. Several genotypes were found, of which the vacA s1 cagA positive strains were predominant. Additionally, a correlation was found between the H. pylori presence in biopsy and its presence in lavage fluid (p=0.015), rendering the latter as an alternative for biopsy. Sensitivity and specificity of lavage fluid analysis were 100% and 67%, respectively.

CONCLUSION

This study shows the vacA s1 cagA positive strain is predominant in a PPU population. The correlation found between the H. pylori presence in biopsy and its presence in lavage fluid suggests that analysis of the lavage fluid is sufficient to determine the H. pylori presence. Risks associated with biopsy taking may be avoided.

Helicobacter pylori endemic and gastric disease

H. pylori infection of the stomach is widespread among human populations including Iranians and is considered to play a major role in the pathogenesis of gastric diseases such as peptic ulcer, adenocarcinoma, and MALT lymphoma. The association between H. pylorivirulence markers and disease has been studied in other populations around the world. The aim of this study was to investigate the distribution of H. pylori vacA and cagA genotypes and their association with clinical outcomes in Iran. H. pylori was cultured from gastric biopsy specimens obtained from 137 Iranian patients (58 with duodenal ulcer, 61 with nonulcer dyspeptic [NUD], and 18 with gastric adenocarcinoma). The vacA alleles and cagA genotypes were determined by PCR. The vacA sl allele was present in 107 of the 137 subjects (78%). Multiple strains (m1 and m2) were detected in H. pylori isolates from the patients. VacA s1 genotypes were more frequent in patients with peptic ulcer (46/58; 79%) than in NUD patients (47/61; 77%). CagA was present in 44% of the patients. NUD patients had a frequency of cagA positivity similar to that of the overall population (46%). CagA was present more frequently more than cagA-negative (20% vs. 8%, respectively) in patients with gastric carcinoma (20%) than cagA-negative in patients with gastric carcinoma (8%). This is the first comprehensive study to demonstrate the frequency of colonization with mixed strain, vacA s1, m1 and m2 as the dominant genotype in these Iranian patients, where a high rate of H. pylori infection exists and is similar to the region with a low rate of H. pylori infection. Therefore, host genetics, environmental factors, and the substantial genetic heterogeneity among different H. pylori strains may contribute to the different clinical outcomes.

cagA and vacA genotype of Helicobacter pylori associated with gastric diseases in Xi’an area

AIM: To establish stock of clinical Helicobacter pylori (H. pylori) isolates, to perform cagA and vacA typing of these isolates, to evaluate the relationship between genotypes of cagA and vacA and upper gastrointestinal diseases and to assess the association of vacA genotypes with presence of the pathogenicity marker-cagA.

METHODS: Clinical H.pylori strains were isolated from the antrum of 259 patients in Clumbia agar. The isolated H. pylori strains were identified by histology, and16SrRNA PCR. CagA genotypes were detected by colony hybridization, the probe was derived from the cloned plasmid PcagA, and digested by EcoRI-HindIII and the isolated PcagA DNA fragment was radioactively labelled by the random priming method. vacA genes types (s,m)and subtypes (s1a, s1b, s2) were typed by PCR. Vacuolating toxin was detected with neutral red absorb test. The results were treated statistically by χ² test, t test, and rank sum test.

RESULTS: A total of 192 clinical H.pylori strains were isolated and the stock of Helicobacter pylori was established. The total positive rate of cagA was 87% in all gastric diseases, and 95% in gastric cancer group. There was a difference between gastric cancer group and the other groups (P < 0.05) except duodenal ulcer group. The expression of type s1 of vacA was more than type s2 (P < 0.05), and, the expression of type m1 was equal to type m2. In gastric cancer group, there was a difference between s1a and s1b (P < 0.05), and s1a was more than s1b. Vacuolating toxins were more in Xi’an area isolates.

CONCLUSION: The cagA⁺ vacA type s1 clinical isolates are more in Xi’an area, but this can not serve as an index to predict gastric cancer.