scholarly journals Random Mutagenesis of Helicobacter pylori vacA To Identify Amino Acids Essential for Vacuolating Cytotoxic Activity

2006 ◽  
Vol 74 (11) ◽  
pp. 6188-6195 ◽  
Author(s):  
Mark S. McClain ◽  
Daniel M. Czajkowsky ◽  
Victor J. Torres ◽  
Gabor Szabo ◽  
Zhifeng Shao ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Cytotoxic Activity ◽  
Point Mutations ◽  
Random Mutagenesis ◽  
Single Amino Acid ◽  
Hydrophobic Region ◽  
Ulcer Disease ◽  
Amino Terminal ◽  
Selective Membrane ◽  
H Pylori

ABSTRACT VacA is a secreted toxin that plays a role in Helicobacter pylori colonization of the stomach and may contribute to the pathogenesis of peptic ulcer disease and gastric cancer. In this study, we analyzed a library of plasmids expressing randomly mutated forms of recombinant VacA and identified 10 mutant VacA proteins that lacked vacuolating cytotoxic activity when added to HeLa cells. The mutations included six single amino acid substitutions within an amino-terminal hydrophobic region and four substitutions outside the amino-terminal hydrophobic region. All 10 mutations mapped within the p33 domain of VacA. By introducing mutations into the H. pylori chromosomal vacA gene, we showed that secreted mutant toxins containing V21L, S25L, G121R, or S246L mutations bound to cells and were internalized but had defects in vacuolating activity. In planar lipid bilayer and membrane depolarization assays, VacA proteins containing V21L and S25L mutations were defective in formation of anion-selective membrane channels, whereas proteins containing G121R or S246L mutations retained channel-forming capacity. These are the first point mutations outside the amino-terminal hydrophobic region that are known to abrogate vacuolating toxin activity. In addition, these are the first examples of mutant VacA proteins that have defects in vacuolating activity despite exhibiting channel activities similar to those of wild-type VacA.

scholarly journals Phenotypic and Genotypic Analysis of Resistant Helicobacter pylori Strains Isolated from Children with Gastrointestinal Diseases

Diagnostics ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 759
Author(s):  
Monika Maria Biernat ◽  
Aldona Bińkowska ◽  
Łukasz Łaczmański ◽  
Paweł Biernat ◽  
Paweł Krzyżek ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Antibiotic Resistance ◽  
Point Mutations ◽  
Gastrointestinal Diseases ◽  
Drug Susceptibility Testing ◽  
Test Method ◽  
Ulcer Disease ◽  
Genotypic Analysis ◽  
Clinical Diagnoses ◽  
H Pylori

Antibiotic resistance of Helicobacter pylori is currently a global issue. The aim of this study was to analyze actual antibiotic resistance rates of H. pylori strains isolated from children with primary infections and to compare the incidence of mutations that determine resistance to clarithromycin (CH) and metronidazole (MET) in children with different clinical diagnoses. A total of 91 H. pylori strains were isolated from 108 children with primary infections. Drug susceptibility testing of the strains was performed using E-test method. Classical sequencing of DNA fragments was used to detect point mutations for CH and MET resistance. Resistance to CH was detected in 31% of isolated strains (28/91), while resistance to MET and CH was detected in 35% (32/91) of strains. A2143G was the most frequently detected mutation and was dominant among strains isolated from children with peptic ulcer disease (80%). Mutations in the rdxA gene were found significantly more frequently among MET-resistant strains than MET-sensitive strains (p = 0.03, Chi2 = 4.3909). In children, a higher frequency of H. pylori multiresistant strains was observed compared with the previous study in the same area. Differences were found in the occurrence of point mutations among H. pylori strains resistant to CH isolated from children with different clinical diagnoses.

scholarly journals Genomic Analysis of Antimicrobial Resistance Genotype-to-Phenotype Agreement in Helicobacter pylori

2020 ◽  
Vol 9 (1) ◽  
pp. 2
Author(s):  
Tal Domanovich-Asor ◽  
Yair Motro ◽  
Boris Khalfin ◽  
Hillary A. Craddock ◽  
Avi Peretz ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Antimicrobial Resistance ◽  
Point Mutations ◽  
Genomic Analysis ◽  
23S Rrna ◽  
Phenotype Correlation ◽  
Bioinformatics Pipeline ◽  
Phenotypic Resistance ◽  
Commercial Kits ◽  
H Pylori

Antimicrobial resistance (AMR) in Helicobacter pylori is increasing and can result in treatment failure and inappropriate antibiotic usage. This study used whole genome sequencing (WGS) to comprehensively analyze the H. pylori resistome and phylogeny in order to characterize Israeli H. pylori. Israeli H. pylori isolates (n = 48) underwent antimicrobial susceptibility testing (AST) against five antimicrobials and WGS analysis. Literature review identified 111 mutations reported to correlate with phenotypic resistance to these antimicrobials. Analysis was conducted via our in-house bioinformatics pipeline targeting point mutations in the relevant genes (pbp1A, 23S rRNA, gyrA, rdxA, frxA, and rpoB) in order to assess genotype-to-phenotype correlation. Resistance rates of study isolates were as follows: clarithromycin 54%, metronidazole 31%, amoxicillin 10%, rifampicin 4%, and levofloxacin 2%. Genotype-to-phenotype correlation was inconsistent; for every analyzed gene at least one phenotypically susceptible isolate was found to have a mutation previously associated with resistance. This was also observed regarding mutations commonly used in commercial kits to diagnose AMR in H. pylori cases. Furthermore, 11 novel point mutations associated with a resistant phenotype were detected. Analysis of a unique set of H. pylori isolates demonstrates that inferring resistance phenotypes from WGS in H. pylori remains challenging and should be optimized further.

scholarly journals Identification of Markers for Helicobacter pylori Strains Isolated from Children with Peptic Ulcer Disease by Suppressive Subtractive Hybridization

2006 ◽  
Vol 74 (7) ◽  
pp. 4064-4074 ◽  
Author(s):  
Mónica Oleastro ◽  
Lurdes Monteiro ◽  
Philippe Lehours ◽  
Francis Mégraud ◽  
Armelle Ménard
Keyword(s):  
Helicobacter Pylori ◽  
Peptic Ulcer ◽  
Peptic Ulcer Disease ◽  
Subtractive Hybridization ◽  
Suppressive Subtractive Hybridization ◽  
Ulcer Disease ◽  
Lipopolysaccharide Biosynthesis ◽  
The Difference ◽  
H Pylori

ABSTRACT Peptic ulcer disease (PUD) occurs after a long-term Helicobacter pylori infection. However, the disease can develop earlier, and rare cases have been observed in children, suggesting that these H. pylori strains may be more virulent. We used suppressive subtractive hybridization for comparative genomics between H. pylori strains isolated from a 5-year-old child with duodenal ulcer and from a sex- and age-matched child with gastritis only. The prevalence of the 30 tester-specific subtracted sequences was determined on a collection of H. pylori strains from children (15 ulcers and 30 gastritis) and from adults (46 ulcers and 44 gastritis). Two of these sequences, jhp0562 (80.0% versus 33.3%, P = 0.008) and jhp0870 (80.0% versus 36.7%, P = 0.015), were highly associated with PUD in children and a third sequence, jhp0828, was less associated (40.0% versus 10.0%, P = 0.048). Among adult strains, none of the 30 sequences was associated with PUD. However, both jhp0562 and jhp0870 were less prevalent in adenocarcinoma strains than in PUD strains from children and adults, the difference being statistically significant for jhp0870. In conclusion, two H. pylori genes were identified as being strongly associated with PUD in children, and their putative roles as an outer membrane protein for jhp0870 and in lipopolysaccharide biosynthesis for jhp0562, suggest that they may be novel virulence factors of H. pylori.

scholarly journals Prevalence of Helicobacter pylori infection among patients undergoing upper gastrointestinal endoscopy

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Vudumula Vijaya Lakshmi
Keyword(s):  
Duodenal Ulcer ◽  
Helicobacter Pylori ◽  
Normal Population ◽  
Gastric Ulcers ◽  
Upper Gastrointestinal Endoscopy ◽  
Contributing Factors ◽  
Duodenal Ulcers ◽  
Female Ratio ◽  
Ulcer Disease ◽  
H Pylori

Helicobacter pylori (H. pylori) has a role in the multifactorial etiology of peptic ulcer disease. A link between H. pylori infection and duodenal ulcer disease is now established. Other contributing factors and their interaction with the organism may initiate the ulcerative process. The fact that eradication of H. pylori infection leads to a long-term cure in the majority of duodenal ulcer patients and the fact that the prevalence of infection is higher in ulcer patients than in the normal population are cogent arguments in favor of it being the primary cause of the ulceration. This study was under taken at the Department of surgery, Narayana medical college, Nellore from January 2007 to July 2008. A total of 150 patients with duodenal ulcers, gastric ulcers, antral gastritis, gastric carcinoma and dyspepsia of any kind were studied. Maximum number of cases were in the age group of 31 years to 50 years among both sexes and number of cases gradually decreased after 50 years of age in males and females. Males were more in number and male to female ratio is (2.75:1) approximately 3:1.

scholarly journals Features of the endoscopic picture in paediatric gastroduodenal diseases caused by Helicobacter pylori

2020 ◽  
Vol 10 (3) ◽  
pp. 543-550
Author(s):  
Sh. T. Turdieva ◽  
E. A. Shamansurova
Keyword(s):  
Helicobacter Pylori ◽  
Inflammatory Diseases ◽  
Gastric Wall ◽  
Duodenogastric Reflux ◽  
Chronic Atrophic Gastritis ◽  
Endoscopic Examination ◽  
Ulcer Disease ◽  
Functional Studies ◽  
H Pylori ◽  
Endoscopic Picture

The aim of the study was to examine the features of the endoscopic picture in the upper digestive tract mucosa in paediatric chronic gastroduodenal pathology (CGDP) associated with Helicobacter pylori. Materials and methods. There were examined 286 patients, aged 6–15 years. Diagnostic criteria for chronic gastroduodenal pathology were anamnestic as well as instrumental and functional studies data: gastric fractional intubation, esophagogastroduodenoscopy (EPGDS) with endoscopic pH-metry without biopsy, and ultrasound examination of abdominal organs. H. pylori testing was carried out by two unrelated methods such as respiratory test and a immunochromatographic fecal test. Results. Detection of H. pylori in children with CGDP peaked in patients with peptic gastric and duodenal ulcer (up to 87.5%, p < 0.05). The main endoscopic signs were edema, hyperaemia and contact bleeding, as well as local haemorrhage were the major endoscopic signs of inflammation in the stomach and duodenum mucosa. Atrophic mucosal lesions were characterized by thinning, pale colour together with transilluminated submucosal vessels. Non-atrophic antral gastritis was featured with delayed gastric emptying, antral stasis and pyloric spasm. In contrast, hypotension of the gastric wall, duodenogastric reflux and decreased motility were more typical to chronic atrophic gastritis. Major endoscopic feature in patients with H. pylori infection was presented by dominant atrophic changes combined with gastroduodenal reflux (77.6%, p < 0.05) compared to patients without H. pylori infection. Conclusion. Detection of HP infection was peaked in children with CGDP coupled to peptic ulcer disease compared to patients with inflammatory diseases (p < 0.05). Endoscopic examination in HP-positive patients showed that atrophic changes were found by 4-fold more frequently together with gastroduodenal reflux compared to patients without HP infection (p < 0.05).

Atypical presentation at acute gastritis: significant gastric wall thickening as a presentation of a primary Helicobacter pylori infection in children

2021 ◽  
Vol 14 (7) ◽  
pp. e243912
Author(s):  
Kiyokuni Nakamura ◽  
Ryo Tamura ◽  
Yoshitomi Yasui ◽  
Hideaki Okajima
Keyword(s):  
Helicobacter Pylori ◽  
Epigastric Pain ◽  
Gastric Wall ◽  
Malignant Tumour ◽  
Wall Thickening ◽  
Atypical Presentation ◽  
Negative Consequences ◽  
Ulcer Disease ◽  
Acute Gastritis ◽  
H Pylori

Helicobacter pylori infection could cause chronic inflammation in the stomach and induce peptic ulcer disease or even malignant tumour. The initial infection of the organism happens in childhood but most of cases are latent. We had a case of 10-year-old girl who presented with acute epigastric pain and significant thickening of the stomach wall on CT. The finding seemed atypical for acute gastritis so oesophagogastroduodenoscopy and serology examination were added and the primary infection of H. pylori was confirmed with the exclusion of other possible diagnoses like eosinophilic gastritis and IgA vasculitis. Acute gastritis is one of the most common sickness in children, however, it would be worthwhile considering further investigation including H. pylori infection in a case of atypical presentation to prevent negative consequences derived from chronic H. pylori infection.

scholarly journals Helicobacter pylori Eradication According to Sequencing-Based 23S Ribosomal RNA Point Mutation Associated with Clarithromycin Resistance

2019 ◽  
Vol 9 (1) ◽  
pp. 54 ◽  
Author(s):  
Seung In Seo ◽  
Byoung Joo Do ◽  
Jin Gu Kang ◽  
Hyoung Su Kim ◽  
Myoung Kuk Jang ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Point Mutation ◽  
Ribosomal Rna ◽  
Eradication Rate ◽  
Point Mutations ◽  
Clarithromycin Resistance ◽  
Clinically Significant ◽  
H Pylori ◽  
23S Ribosomal Rna ◽  
Significant Point

Background/Aims: Clarithromycin resistance in Helicobacter pylori is associated with point mutations in the 23S ribosomal RNA (rRNA) gene. We investigated the point mutations in the 23S rRNA genes of patients with clarithromycin-resistant H. pylori and compared the H. pylori eradication rates based on the point mutations. Methods: A total of 431 adult patients with H. pylori infection were recruited in Kangdong Sacred Heart Hospital in 2017 and 2018. Patients who did not have point mutations related to clarithromycin resistance and/or had clinically insignificant point mutations were treated with PAC (proton pump inhibitor, amoxicillin, clarithromycin) for seven days, while patients with clinically significant point mutations were treated with PAM (proton pump inhibitor, amoxicillin, metronidazole) for seven days. H. pylori eradication rates were compared. Results: Sequencing-based detection of point mutations identified four mutations that were considered clinically significant (A2142G, A2142C, A2143G, A2143C). The clarithromycin resistance rate was 21.3% in the overall group of patients. A2143G was the most clinically significant point mutation (84/431, 19.5%), while T2182C was the most clinically insignificant point mutation (283/431, 65.7%). The overall H. pylori eradication rate was 83.7%, and the seven-day PAM-treated clarithromycin-resistance group showed a significantly lower eradication rate than the seven-day PAC-treated nonresistance group (ITT; 55.4% (51/92) vs. 74.3% (252/339), p = 0.001, PP; 66.2% (51/77) vs. 88.4% (252/285), p = 0.0001). Conclusions: There were significantly lower eradication rates in the patients with clarithromycin-resistant H. pylori when treated with PAM for seven days. A future study comparing treatment regimens in clarithromycin-resistant H. pylori-infected patients may be necessary.

Helicobacter pylori causes gastrointestinal hemorrhage in patients with congenital bleeding disorders

2003 ◽  
Vol 89 (04) ◽  
pp. 741-746 ◽  
Author(s):  
Ann-Sofie Rehnberg ◽  
Marju Hein ◽  
Olga Hegedus ◽  
Per Lindmarker ◽  
Per Hellström ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Gastrointestinal Hemorrhage ◽  
Breath Test ◽  
Eradication Therapy ◽  
Urea Breath Test ◽  
Von Willebrand Disease ◽  
Bleeding Disorders ◽  
Ulcer Disease ◽  
H Pylori ◽  
One Year

Summary Helicobacter pylori (H. pylori) infection is associated with peptic ulcer disease and gastric cancer. The eradication of H. pylori is of special interest in patients with congenital bleeding disorders, for whom treatment of gastrointestinal hemorrhage with factor concentrates is costly. The prevalence of H. pylori varies between different populations and identification of high-risk subgroups may allow for more targeted screening and eradication of the infection. We performed a 5-year retrospective study of gastrointestinal bleeding, combined with screening and treatment for H. pylori and a long-term prospective follow-up in 168 Swedish and 23 Estonian patients with hemophilia or von Willebrand disease. The prevalence of seropositivity was lower in Sweden than in Estonia (28 versus 48%, p = 0.03), lower in native Swedes than in non-Nordic immigrants to Sweden (20 versus 76%, p = 0.0001) and lower in patients less than 40 years of age than older patients (16 versus 38%, p = 0.002). The incidence of gastrointestinal hemorrhages among the 35 Swedish patients with active H. pylori infection, confirmed by a urea breath test, was 6.0 per 100 patient-years before eradication therapy versus 1.7 during the prospective followup. A negative urea breath test one month after therapy always remained negative after one year. Screening, followed by treatment of all infected patients, yielded a reduction of direct costs over a 5-year period of 130 US-$ per screened patient. We conclude that screening and eradication therapy for infection with H. pylori in patients with congenital bleeding disorders is an effective and economic strategy.

scholarly journals Macrolide resistance in Helicobacter pylori: rapid detection of point mutations and assays of macrolide binding to ribosomes.

1997 ◽  
Vol 41 (12) ◽  
pp. 2724-2728 ◽  
Author(s):  
A Occhialini ◽  
M Urdaci ◽  
F Doucet-Populaire ◽  
C M Bébéar ◽  
H Lamouliatte ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Point Mutations ◽  
Restriction Enzymes ◽  
The United States ◽  
Drug Binding ◽  
Macrolide Resistance ◽  
Rrna Genes ◽  
23S Rrna ◽  
Dependent Manner ◽  
H Pylori

Resistance of Helicobacter pylori to macrolides is a major cause of failure of eradication therapies. Single base substitutions in the H. pylori 23S rRNA genes have been associated with macrolide resistance in the United States. Our goal was to extend this work to European strains, to determine the consequence of this mutation on erythromycin binding to H. pylori ribosomes, and to find a quick method to detect the mutation. Seven pairs of H. pylori strains were used, the parent strain being naturally susceptible to macrolides and the second strain having acquired an in vivo resistance during a treatment regimen that included clarithromycin. The identity of the strains was confirmed by random amplified polymorphic DNA testing with two different primers, indicating that resistance was the result of the selection of variants of the infecting strain. All resistant strains were found to have point mutations at position 2143 (three cases) or 2144 (four cases) but never on the opposite DNA fragment of domain V of the 23S rRNA gene. The mutation was A-->G in all cases except one (A-->C) at position 2143. Using BsaI and BbsI restriction enzymes on the amplified products, we confirmed the mutations of A-->G at positions 2144 and 2143, respectively. Macrolide binding was tested on purified ribosomes isolated from four pairs of strains with [14C]erythromycin. Erythromycin binding increased in a dose-dependent manner for the susceptible strain but not for the resistant one. In conclusion we suggest that the limited disruption of the peptidyltransferase loop conformation, caused by a point mutation, reduces drug binding and consequently confers resistance to macrolides. Finally, the macrolide resistance could be detected without sequencing by performing restriction fragment length polymorphism with appropriate restriction enzymes.

scholarly journals Mutated Rnf43 Aggravates Helicobacter Pylori-Induced Gastric Pathology

Cancers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 372 ◽  
Author(s):  
Victoria Neumeyer ◽  
Michael Vieth ◽  
Markus Gerhard ◽  
Raquel Mejías-Luque
Keyword(s):  
Helicobacter Pylori ◽  
Tumor Suppressor ◽  
Point Mutations ◽  
Ring Finger ◽  
Stem Cell Marker ◽  
Ring Finger Protein ◽  
Functional Studies ◽  
Finger Protein ◽  
H Pylori ◽  
Key Events

The E3 ubiquitin ligase ring finger protein 43 (RNF43) is frequently mutated in gastric tumors and loss of RNF43 expression was suggested to be one of the key events during the transition from adenoma to gastric carcinoma. Functional studies on RNF43 have shown that it acts as a tumor suppressor by negatively regulating Wnt signaling. Interestingly, we observed that RNF43H292R/H295R mice bearing two point mutations in the ring domain displayed thickening of the mucosa at early age but did not develop neoplasia. In this study, we infected these mice for 6 months with Helicobacter pylori, which has been described as one of the major risk factors for gastric cancer. Mice bearing mutant RNF43H292R/H295R showed higher gastritis scores upon H. pylori infection compared to wild-type mice, accompanied by increased lymphocyte infiltration and Ifng levels. Furthermore, infected Rnf43 mutant mice developed atrophy, hyperplasia and MUC2 expressing metaplasia and displayed higher levels of the gastric stem cell marker CD44 and canonical NF-κB signaling. In summary, our results show that transactivating mutations in the tumor suppressor Rnf43 can worsen H. pylori induced pathology.

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