DNA-Level Characterization of Helicobacter pylori Strains from Patients with Overt Disease and with Benign Infections in Bangladesh (original) (raw)
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Journal of Clinical Microbiology, 2002
We compared putative molecular markers of virulence ( vacA , cagA , and iceA ) of Helicobacter pylori strains isolated from 52 adult duodenal ulcer patients from West Bengal, India, with those of H . pylori strains isolated from 48 adult healthy volunteers from the same region. On the basis of genotyping by PCR, we conclude that the H. pylori strains isolated from the two study groups were indistinguishable and that there are geographic variations in the association of certain putative H. pylori virulence genes with clinical status.
Saudi Journal of Gastroenterology, 2013
Helicobacter pylori is a Gram-negative bacteria that inhabit the gastric mucosal lining. Adhesion of the bacteria to the gastric mucosa is a necessary prerequisite for the pathogenesis of H. pylori-related diseases. Although most patients are asymptomatic, persistent infection may cause chronic gastritis, gastric ulcer, gastric cancer, and duodenal ulcer. The prevalence varies among countries with existing evidence suggesting that the diversity in disease outcome may be ascribed to variations in infecting strains. [1,2] The virulence markers of H. pylori, such as cytotoxin-associated genes A (cagA) and E (cagE), vacuolating cytotoxin (vacA) and its alleles have been shown to be associated with its various manifestations. [3] H. pylori genotypes and their geographic distribution are linked to the severity of peptic ulcer disease (PUD). [4,5] The H. pylori genome is genetically diverse, as it can be seen in the cag pathogenicity island (PAI) and allelic variation within the vacA gene. [5,6] The cytotoxin-associated gene A (cagA) has been proposed as a marker for the cag PAI and is associated with more severe clinical outcomes. [3-5] The cag PAI genes contain a cagE gene that encodes a secretory protein that is required for the induction of interleukin-8 and for translocation and phosphorylation of CagA protein. [7,8] The cagE genotype has been associated with gastric cancer in ABSTRACT Background/Aim: Helicobacter pylori is a Gram-negative bacteria, which is associated with development of gastroduodenal diseases. The prevalence of H. pylori and the virulence markers cytotoxin-associated gene A and E (cagA, cagE) and vacuolating-associated cytotoxin gene (vacA) alleles varies in different parts of the world. H. pylori virulence markers cagA, cagE, and vacA alleles in local and Afghan nationals with H. pylori-associated gastroduodenal diseases were studied. Patients and Methods: Two hundred and ten patients with upper gastrointestinal symptoms and positive for H. pylori by the urease test and histology were included. One hundred and nineteen were local nationals and 91 were Afghans. The cagA, cagE, and vacA allelic status was determined by polymerase chain reaction. Results: The nonulcer dyspepsia (NUD) was common in the Afghan patients (P = 0.025). In Afghan H. pylori strains, cagA was positive in 14 (82%) with gastric carcinoma (GC) compared with 29 (45%) with NUD (P = 0.006), whereas cagE was positive in 11 (65%) with GC and 4 (67%) with duodenal ulcer (DU) compared with 12 (18%) with NUD (P < 0.001 and 0.021, respectively). The vacA s1a/b1was positive in 10 (59%) of GC compared with 20 (31%) in NUD (P = 0.033). In Pakistani strains, cagE was positive in 12 (60%) with GC, 7 (58%) with GU, 12 (60%) with DU compared with 11 (16%) with NUD (P < 0.001, 0.004, and < 0.001, respectively). In Pakistani strains, cagA/s1a/m1 was 39 (33%) compared with Afghans in 17 (19%) (P = 0.022). Moderate to severe mucosal inflammation was present in 51 (43%) Pakistani patients compared with 26 (28%) (P = 0.033) in Afghans. It was also associated with grade 1 lymphoid aggregate development in Pakistani patients 67 (56%) compared with 36 (40%) (P = 0.016) in Afghans. Conclusion: Distribution of H. pylori virulence marker cagE with DU was similar in Afghan and Pakistan H. pylori strains. Chronic active inflammation was significantly associated with Pakistani H. pylori strains.
2015
Introduction: Helicobacter pylori is a microaerophilic, spiral shaped, unipolar flagellated, gram negative organism which has high tropism towards gastric epithelial cells and may lead to a severe form of gastroduodenal disease. Prevalence of H pylori infections in developing countries may exceed 70% but only a fraction of people develop severe disease. The involvement of H. pylori virulence factors cagA and vacA genotypes are well studied and show high genetic diversity geographically. The present study was conducted to detect the Presence of H. pylori in biopsy samples from symptomatic patients by Rapid Urease Test, histopathological examination and Culture .It also involved the detection of virulence genes cagA, vacA (s1m1, s1m2 and s2m2) genotypes from the isolated strains. Materials and Methods: Patients with complaints of abdominal pain, discomfort, acidity and loss of appetite were chosen for endoscopy. A detailed history was taken and physical examination of the patients was...
Aims: Helicobacter pylori is a causative agent of gastroduodenal diseases in Bangladesh as well as throughout the world. This study aimed to determine the H. pylori cagA, vacA and iceA virulent genotypes by PCR directly in gastric biopsies from dyspeptic patients of Chittagong, Bangladesh and evaluating the association of these genotypes with clinical manifestations. Methodology and results: CLO (Campylobacter-Like Organism) test and Hp16s PCR (16S rRNA based H. pylori specific PCR) was performed to confirm H. pylori infection. Among 111 patients, H. pylori infection was found in 60 patients by CLO test, while Hp16s PCR revealed that 54 patients were H. pylori positive. PCR amplification of the H. pylori virulence genes was successful in 35 gastric biopsies amongst the 54 Hp16s PCR positive biopsies. The positive rates for the cagA, vacAs1, vacAs2, vacAm1, vacAm2, iceA1, iceA2 genes were 34.3%, 71.4%, 8.6%, 62.9%, 28.6%, 20% and 11.4%, respectively. The allelic variant vacAs1m1 had a predominant percentage with 51.4%, followed by vacAs1m2, vacAs2m2 and vacAs1m1m2 with 14.3%, 5.7% and 2.9%, respectively. Among the subtypes of vacAs1, only s1a was detected in 54.3% of biopsies while none of the cases showed the s1b and s1c genotypes. However, there was no statistically significant association (P>0.05) observed between the virulent genotypes and clinical conditions. Conclusion, significance and impact of study: We found that cagA, vacAs1m1 and iceA1 were the most frequent H. pylori genotypes in severe clinical outcomes of the infection. The data in this study would provide a basis for understanding the diverse virulence pattern of this bacterium in Bangladeshi dyspeptic patients.
Aims: Helicobacter pylori is a causative agent of gastroduodenal diseases in Bangladesh as well as throughout the world. This study aimed to determine the H. pylori cagA, vacA and iceA virulent genotypes by PCR directly in gastric biopsies from dyspeptic patients of Chittagong, Bangladesh and evaluating the association of these genotypes with clinical manifestations. Methodology and results: CLO (Campylobacter-Like Organism) test and Hp16s PCR (16S rRNA based H. pylori specific PCR) was performed to confirm H. pylori infection. Among 111 patients, H. pylori infection was found in 60 patients by CLO test, while Hp16s PCR revealed that 54 patients were H. pylori positive. PCR amplification of the H. pylori virulence genes was successful in 35 gastric biopsies amongst the 54 Hp16s PCR positive biopsies. The positive rates for the cagA, vacAs1, vacAs2, vacAm1, vacAm2, iceA1, iceA2 genes were 34.3%, 71.4%, 8.6%, 62.9%, 28.6%, 20% and 11.4%, respectively. The allelic variant vacAs1m1 had a predominant percentage with 51.4%, followed by vacAs1m2, vacAs2m2 and vacAs1m1m2 with 14.3%, 5.7% and 2.9%, respectively. Among the subtypes of vacAs1, only s1a was detected in 54.3% of biopsies while none of the cases showed the s1b and s1c genotypes. However, there was no statistically significant association (P>0.05) observed between the virulent genotypes and clinical conditions. Conclusion, significance and impact of study: We found that cagA, vacAs1m1 and iceA1 were the most frequent H. pylori genotypes in severe clinical outcomes of the infection. The data in this study would provide a basis for understanding the diverse virulence pattern of this bacterium in Bangladeshi dyspeptic patients.
Indian Journal of Medical Microbiology, 2018
Original Article intrODuctiOn Helicobacter pylori is a spiral, micro-aerophilic, Gram-negative pathogenic bacterium which colonises the human gastric mucosa in almost half of the world's population. This bacterium is responsible for a number of stomach disorders such as chronic gastritis and peptic ulcer disease and might also be a triggering agent for various kinds of gastric lymphomas. [1] The pathogenesis as well as the diversity in outcome of infection may be attributed to a variety of genetic markers-the most important being the vacuolating cytotoxin (vacA) gene and the cytotoxin-associated gene (cagA). [2] H. pylori produces a vacuolating cytotoxin, a 95-kDa highly immunogenic protein encoded by the vacA gene, which is associated with the severity of gastroduodenal diseases by significantly contributing to peptic ulceration as well as gastric carcinoma. It is a pore-forming toxin present in almost all H. pylori strains and causes massive injury to the primary gastric epithelial cells in vitro by inducing the formation of vacuoles. VacA results in the formation of membrane channel and interferes with cytoskeleton-dependent cell functions, thus inducing apoptosis as well as modulation of the immune system. [2,3] The vacA gene consists of two variable regions; the signal peptide region(s) and middle region(m) and three allelic s subtypes called s1a, s1b and s2 and two m types, called m1 and m2. There is a strong correlation between the Background: Helicobacter pylori, the gastric bacterium, is widely known to be one of the most genetically diverse group of organisms whose pathogenesis as well as the diversity in infection outcome may be attributed to a variety of virulent genes. Aim: This study aimed to study the molecular profile of H. pylori vacA gene by determining the phylogenetic relatedness and genetic diversity of the strains isolated in this region with those of other geographical regions. Materials and Methods: A total of twenty H. pylori clinical strains were isolated from randomly selected 100 patients suffering from gastroduodenal diseases as well as endoscopically normal patients in a cross-sectional hospital-based setting from January 2016 to May 2017. VacA signal sequence and mid regions of H. pylori were amplified by polymerase chain reaction followed by DNA sequencing and phylogenetic analysis. Results: VacA s1m1 allelic variant was more prevalent in our study, regardless of the clinical outcomes. Phylogenetic analysis of VacA s1 strains revealed clustering of most of the strains. VacA m1 strains clustered with Bangladesh strains which is a country nearest to India. Conclusion: Prevalence of VacA s1m1 strains may account for high risk of transmission of this gastric pathogen and the overall risk of acquiring infection. Phylogenetic analysis results suggests the prevalence of high genetic diversity in our region. Our findings may aid in developing a better understanding of the genetic structure of H. pylori and the pathophysiology of associated diseases, thus facilitating the implementation of various treatment options.
BMC Gastroenterology
Background: The global prevalence of H. pylori approaches 50%, with prevalence rates between 20 and 40% in developed countries and up to 90% in Africa and other developing nations of the world. Development of H. pylori-associated diseases is determined by a number of virulence factors. This study aimed at determining the prevalence of H. pylori infections and virulence genes (cagA, dupA, and vacA); the relationship between virulence factors and gastroduodenal diseases among patients. Methods: Gastric biopsies were obtained from patients and cultured, DNA was extracted from cultured isolates and biopsies for PCR assay after which samples were investigated using standard laboratory procedures. Data of associated risk factors were obtained with the aid of questionnaires. Results: Of the 444 participants, H. pylori was detected in 115 (25.9%) from culture analysis and 217 (48.9%) by direct PCR method. Ninety-eight (85.2%) of the culture-positive patients were also detected by PCR giving an overall prevalence of 52.7% (234/444). The highest number of H. pylori isolates 76.9% (180/234) was obtained from patients suffering from pangastritis. The CagA virulence gene was found in 62% (145/234), dupA in 53.4% (125/234) and vacA in 90.6% (212/234). VacA genotype s1 m1 was the most prevalent [56.4% (132)] followed by s2 m2 [11.5% (27)], s2 m1 [10.3% (24)] and [s1 m2 9.4% (22)]. There was a significant association observed in vacA s1 and peptic ulcer disease, as well as vacA s1/m2 and gastric erosion (P < 0.05). Conclusion: The study revealed a significant association between virulence genes and the development of certain forms of gastric infections while the variations in H. pylori detection and the associated risk factors investigated in the study were not significantly related.
Frequency of Helicobacter pylori vacA genotypes in Iranian patients with gastric and duodenal ulcer
Journal of Infection and Public Health, 2009
Helicobacter pylori infection is a risk factor for developing chronic peptic ulcers and gastric cancer. The purpose of this study was to investigate the frequency of Helicobacter pylori vacA genotypes in patients with gastric and duodenal ulcer. A total of 100 biopsy specimens of patients with gastric (n = 50) and duodenal (n = 50) ulcer were collected. The specimens were cultured on selective media and incubated in a microaerophilic atmosphere at 37 • C for 5-10 days. The isolates were characterized to species level by conventional biochemical tests. The extracted DNA from isolates was used to perform a polymerase chain reaction based, simultaneous analysis of the cagA status, allelic variation of the signal regions (s1, s2) and the middle regions (m1, m2) of the vacA gene. H. pylori isolated from 50 specimens of patients and the vacA gene was detected in all isolates. Among vacA genotypes the s1/m1 was the most common in H. pylori isolates from patients with gastric ulcer (56%) and duodenal ulcer (68%). This study demonstrated that vacA slml is common genotype of H. pylori in patients with peptic ulcer and the vacA allele s1 of this bacterium is associated with ulcer.