scholarly journals Helicobacter pylori is killed by nitrite under acidic conditions

Gut ◽  
1998 ◽  
Vol 42 (3) ◽  
pp. 334-337 ◽  
Author(s):  
R S Dykhuizen ◽  
A Fraser ◽  
H McKenzie ◽  
M Golden ◽  
C Leifert ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Anaerobic Bacteria ◽  
Antimicrobial Effect ◽  
Human Stomach ◽  
Bacterial Survival ◽  
Novel Host ◽  
Potassium Nitrite ◽  
Acidic Conditions ◽  
H Pylori ◽  
Facultative Anaerobic Bacteria

Background—Due to the expression of urease,Helicobacter pylori is able to establish itself in the human stomach under acidic conditions. A novel host defence mechanism was recently proposed, suggesting that the formation of salivary nitrite in symbiosis with facultative anaerobic bacteria in the oropharynx, is aimed at enhancing the antimicrobial activity of gastric juice.Aims—To investigate whether the addition of nitrite in physiological concentrations influences the resistance ofH pylori to acid.Methods—H pylori cultured from fresh gastric biopsy specimens was exposed for 30 minutes to normal saline and to HCl/KCl buffer (0.2M) at pH 2 with urea (5 mM) added. The influence of potassium nitrite (50–1000 μmol/l) on bacterial survival was determined.Results—Addition of nitrite (1 mM) to acidic solutions (pH 2) resulted in complete kill of H pyloriwithin 30 minutes exposure time whereas acid alone allowed the organism to survive (p<0.001). The antimicrobial effect of nitrite at pH 2 against H pylori was dose dependent and complete kill of organisms occurred at concentrations ⩾500 μmol/l.Conclusion—Acidified nitrite has antibacterial activity against H pylori. This should prompt further research into the effect of salivary nitrite on the survival of H pylori in the human stomach.

scholarly journals The Helicobacter pylori UreI Protein Is Not Involved in Urease Activity but Is Essential for Bacterial Survival In Vivo

1998 ◽  
Vol 66 (9) ◽  
pp. 4517-4521 ◽  
Author(s):  
Stéphane Skouloubris ◽  
Jean-Michel Thiberge ◽  
Agnès Labigne ◽  
Hilde De Reuse
Keyword(s):  
Helicobacter Pylori ◽  
Urease Activity ◽  
Saline Solution ◽  
Integral Membrane Protein ◽  
Bacterial Survival ◽  
Acidic Conditions ◽  
H Pylori ◽  
Phosphate Buffered Saline

ABSTRACT We produced defined isogenic Helicobacter pylori ureImutants to investigate the function of UreI, the product of one of the genes of the urease cluster. The insertion of a catcassette had a strong polar effect on the expression of the downstream urease genes, resulting in very weak urease activity. Urease activity, measured in vitro, was normal in a strain in which ureI was almost completely deleted and replaced with a nonpolar cassette. In contrast to previous reports, we thus found that the product ofureI was not necessary for the synthesis of active urease. Experiments with the mouse-adapted H. pylori SS1 strain carrying the nonpolar ureI deletion showed that UreI is essential for H. pylori survival in vivo and/or colonization of the mouse stomach. The replacement of ureIwith the nonpolar cassette strongly reduced H. pylorisurvival in acidic conditions (1-h incubation in phosphate-buffered saline solution at pH 2.2) in the presence of 10 mM urea. UreI is predicted to be an integral membrane protein and may therefore be involved in a transport process essential for H. pylori survival in vivo.

scholarly journals The Hsp60 Protein of Helicobacter Pylori Exhibits Chaperone and ATPase Activities at Elevated Temperatures

BioChem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 19-25
Author(s):  
Jose A. Mendoza ◽  
Julian L. Ignacio ◽  
Christopher M. Buckley
Keyword(s):  
Helicobacter Pylori ◽  
Heat Stress ◽  
Molecular Chaperone ◽  
Elevated Temperatures ◽  
Citrate Synthase ◽  
Gastric Epithelium ◽  
Acidic Conditions ◽  
H Pylori ◽  
Induced Aggregation ◽  
Hydrolysis Of

The heat-shock protein, Hsp60, is one of the most abundant proteins in Helicobacter pylori. Given its sequence homology to the Escherichia coli Hsp60 or GroEL, Hsp60 from H. pylori would be expected to function as a molecular chaperone in this organism. H. pylori is a type of bacteria that grows on the gastric epithelium, where the pH can fluctuate between neutral and 4.5, and the intracellular pH can be as low as 5.0. We previously showed that Hsp60 functions as a chaperone under acidic conditions. However, no reports have been made on the ability of Hsp60 to function as a molecular chaperone under other stressful conditions, such as heat stress or elevated temperatures. We report here that Hsp60 could suppress the heat-induced aggregation of the enzymes rhodanese, malate dehydrogenase, citrate synthase, and lactate dehydrogenase. Moreover, Hsp60 was found to have a potassium and magnesium-dependent ATPase activity that was stimulated at elevated temperatures. Although, Hsp60 was found to bind GTP, the hydrolysis of this nucleotide could not be observed. Our results show that Hsp60 from H. pylori can function as a molecular chaperone under conditions of heat stress.

scholarly journals Mutational Analysis of Metronidazole Resistance in Helicobacter pylori

2005 ◽  
Vol 49 (3) ◽  
pp. 1236-1237 ◽  
Author(s):  
Jill M. Moore ◽  
Nina R. Salama
Keyword(s):  
Helicobacter Pylori ◽  
Mutational Analysis ◽  
Transposon Mutagenesis ◽  
Human Stomach ◽  
Metronidazole Resistance ◽  
H Pylori ◽  
Chromosomal Loci

ABSTRACT Metronidazole is one of a few antibiotics effective in eliminating Helicobacter pylori infection of the human stomach. Several chromosomal loci have been implicated in resistance to this drug. Saturation transposon mutagenesis of the H. pylori genome revealed inactivation of the rdxA gene as uniquely able to confer metronidazole resistance.

scholarly journals Small Molecule Inhibitors of the Response Regulator ArsR Exhibit Bactericidal Activity against Helicobacter pylori

2020 ◽  
Vol 8 (4) ◽  
pp. 503 ◽  
Author(s):  
Andrés González ◽  
Javier Casado ◽  
Eduardo Chueca ◽  
Sandra Salillas ◽  
Adrián Velázquez-Campoy ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Antibiotic Resistance ◽  
High Throughput Screening ◽  
Lithocholic Acid ◽  
Response Regulator ◽  
Bacterial Pathogen ◽  
Antimicrobial Effect ◽  
Chemical Library ◽  
Secondary Bile Acid ◽  
H Pylori

Helicobacter pylori is considered the most prevalent bacterial pathogen in humans. The increasing antibiotic resistance evolved by this microorganism has raised alarm bells worldwide due to the significant reduction in the eradication rates of traditional standard therapies. A major challenge in this antibiotic resistance crisis is the identification of novel microbial targets whose inhibitors can overcome the currently circulating resistome. In the present study, we have validated the use of the essential response regulator ArsR as a novel and promising therapeutic target against H. pylori infections. A high-throughput screening of a repurposing chemical library using a fluorescence-based thermal shift assay identified several ArsR binders. At least four of these low-molecular weight compounds noticeably inhibited the DNA binding activity of ArsR and showed bactericidal effects against antibiotic-resistant strains of H. pylori. Among the ArsR inhibitors, a human secondary bile acid, lithocholic acid, quickly destroyed H. pylori cells and exhibited partial synergistic action in combination with clarithromycin or levofloxacin, while the antimicrobial effect of this compound against representative members of the normal human microbiota such as Escherichia coli and Staphylococcus epidermidis appeared irrelevant. Our results enhance the battery of novel therapeutic tools against refractory infections caused by multidrug-resistant H. pylori strains.

scholarly journals Helicobacter pylori–binding nonacid glycosphingolipids in the human stomach

2018 ◽  
Vol 293 (44) ◽  
pp. 17248-17266 ◽  
Author(s):  
Chunsheng Jin ◽  
Angela Barone ◽  
Thomas Borén ◽  
Susann Teneberg
Keyword(s):  
Helicobacter Pylori ◽  
Gastric Mucosa ◽  
Structural Complexity ◽  
Human Stomach ◽  
Carbohydrate Binding ◽  
Human Gastric Mucosa ◽  
H Pylori ◽  
Contrast Information

Helicobacter pylori has a number of well-characterized carbohydrate-binding adhesins (BabA, SabA, and LabA) that promote adhesion to the gastric mucosa. In contrast, information on the glycoconjugates present in the human stomach remains unavailable. Here, we used MS and binding of carbohydrate-recognizing ligands to characterize the glycosphingolipids of three human stomachs from individuals with different blood group phenotypes (O(Rh−)P, A(Rh+)P, and A(Rh+)p), focusing on compounds recognized by H. pylori. We observed a high degree of structural complexity, and the composition of glycosphingolipids differed among individuals with different blood groups. The type 2 chain was the dominating core chain of the complex glycosphingolipids in the human stomach, in contrast to the complex glycosphingolipids in the human small intestine, which have mainly a type 1 core. H. pylori did not bind to the O(Rh−)P stomach glycosphingolipids, whose major complex glycosphingolipids were neolactotetraosylceramide, the Lex, Lea, and H type 2 pentaosylceramides, and the Ley hexaosylceramide. Several H. pylori-binding compounds were present among the A(Rh+)P and A(Rh+)p stomach glycosphingolipids. Ligands for BabA-mediated binding of H. pylori were the Leb hexaosylceramide, the H type 1 pentaosylceramide, and the A type 1/ALeb heptaosylceramide. Additional H. pylori-binding glycosphingolipids recognized by BabA-deficient strains were lactosylceramide, lactotetraosylceramide, the x2 pentaosylceramide, and neolactohexaosylceramide. Our characterization of human gastric receptors required for H. pylori adhesion provides a basis for the development of specific compounds that inhibit the binding of this bacterium to the human gastric mucosa.

scholarly journals The Action of Bismuth against Helicobacter pylori Mimics but Is Not Caused by Intracellular Iron Deprivation

2004 ◽  
Vol 48 (6) ◽  
pp. 1983-1988 ◽  
Author(s):  
Michael V. Bland ◽  
Salim Ismail ◽  
Jack A. Heinemann ◽  
Jacqueline I. Keenan
Keyword(s):  
Helicobacter Pylori ◽  
Antimicrobial Effect ◽  
Iron Limitation ◽  
Intracellular Iron ◽  
Colloidal Bismuth Subcitrate ◽  
Iron Deprivation ◽  
Atp Levels ◽  
Bismuth Subcitrate ◽  
Membrane Changes ◽  
H Pylori

ABSTRACT Helicobacter pylori is highly susceptible to bismuth, a heavy metal with antimicrobial activity linked to its effect on bacterial iron uptake. Three strains of H. pylori were analyzed for indicators of iron limitation following exposure to the MIC of colloidal bismuth subcitrate (MICCBS). Similar morphologic and outer membrane changes were observed following growth in iron-limiting medium and at the MICCBS that inhibited the growth of all three strains. These changes, which were also observed for iron-limited bacteria, were alleviated by the addition of iron to the cultures. H. pylori ATP levels, reduced in iron-limiting medium, were below the limits of detection in two of the three strains following exposure to bismuth. The addition of iron partially restored bacterial ATP levels in these two strains, although not to normal concentrations. In contrast, exposure of the same strains to the MICCBS failed to deplete intracellular levels of iron, which were significantly reduced by culturing in iron-limiting medium. Thus, the antimicrobial effect of bismuth and of iron limitation on H. pylori may be similar. However, the respective mechanisms of intracellular action would appear to be mediated by different pathways within the cell.

scholarly journals Regulation of Cell Growth during Serum Starvation and Bacterial Survival in Macrophages by the Bifunctional Enzyme SpoT in Helicobacter pylori

2008 ◽  
Vol 190 (24) ◽  
pp. 8025-8032 ◽  
Author(s):  
Yan Ning Zhou ◽  
William G. Coleman ◽  
Zhaoxu Yang ◽  
Yi Yang ◽  
Nathaniel Hodgson ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Cell Growth ◽  
Intracellular Survival ◽  
Hydrolase Activity ◽  
Serum Starvation ◽  
Bifunctional Enzyme ◽  
Synthetase Activity ◽  
Bacterial Survival ◽  
H Pylori

ABSTRACT In Helicobacter pylori the stringent response is mediated solely by spoT. The spoT gene is known to encode (p)ppGpp synthetase activity and is required for H. pylori survival in the stationary phase. However, neither the hydrolase activity of the H. pylori SpoT protein nor the role of SpoT in the regulation of growth during serum starvation and intracellular survival of H. pylori in macrophages has been determined. In this study, we examined the effects of SpoT on these factors. Our results showed that the H. pylori spoT gene encodes a bifunctional enzyme with both a hydrolase activity and the previously described (p)ppGpp synthetase activity, as determined by introducing the gene into Escherichia coli relA and spoT defective strains. Also, we found that SpoT mediates a serum starvation response, which not only restricts the growth but also maintains the helical morphology of H. pylori. Strikingly, a spoT null mutant was able to grow to a higher density in serum-free medium than the wild-type strain, mimicking the “relaxed” growth phenotype of an E. coli relA mutant during amino acid starvation. Finally, SpoT was found to be important for intracellular survival in macrophages during phagocytosis. The unique role of (p)ppGpp in cell growth during serum starvation, in the stress response, and in the persistence of H. pylori is discussed.

scholarly journals Helicobacter pylori Accumulates Photoactive Porphyrins and Is Killed by Visible Light

2005 ◽  
Vol 49 (7) ◽  
pp. 2822-2827 ◽  
Author(s):  
Michael R. Hamblin ◽  
Jennifer Viveiros ◽  
Changming Yang ◽  
Atosa Ahmadi ◽  
Robert A. Ganz ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Visible Light ◽  
Propionibacterium Acnes ◽  
Protoporphyrin Ix ◽  
Human Stomach ◽  
Drug Resistant ◽  
Violet Light ◽  
Resistant Strains ◽  
H Pylori ◽  
Drug Resistant Strains

ABSTRACT Helicobacter pylori colonizes the mucus layer of the human stomach and duodenum, causes chronic gastritis, gastric ulcer, and is a risk factor for gastric adenocarcinoma. There is a 20% failure rate in antibiotic therapy, which is increasingly due to antibiotic resistance and necessitates the search for alternative antimicrobial methods. We have discovered that H. pylori when cultured in liquid medium, accumulates significant quantities of coproporphyrin and protoporphyrin IX, both in the cells and secreted into the medium. These photoactive porphyrins lead to cell death (up to 5 logs) by photodynamic action upon illumination with low doses of visible light, with blue/violet light being most efficient. The degree of killing increases with the age of the culture and is greater than that found with Propionibacterium acnes (another bacterium known to be photosensitive due to porphyrin accumulation). Both virulent and drug-resistant strains are killed. The data suggest that phototherapy might be used to treat H. pylori infection in the human stomach.

scholarly journals In Vitro Probiotic Potential of Lactic Acid Bacteria Isolated from Aguamiel and Pulque and Antibacterial Activity Against Pathogens

2019 ◽  
Vol 9 (3) ◽  
pp. 601 ◽  
Author(s):  
Alicia Cervantes-Elizarrarás ◽  
Nelly Cruz-Cansino ◽  
Esther Ramírez-Moreno ◽  
Vicente Vega-Sánchez ◽  
Norma Velázquez-Guadarrama ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Helicobacter Pylori ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Eradication Therapy ◽  
Antimicrobial Effect ◽  
E Coli ◽  
Probiotic Potential ◽  
H Pylori

Probiotics can act as a natural barrier against several pathogens, such Helicobacter pylori, a bacterium linked to stomach cancer. The aim of the present study was to isolate and identify lactic acid bacteria (LAB) from pulque and aguamiel, and evaluate their probiotic potential and antimicrobial effect on Escherichia coli, Staphylococcus aureus, and Helicobacter pylori. Ten isolates were selected and evaluated for in vitro resistance to antibiotics and gastrointestinal conditions, and antimicrobial activity against E. coli and S. aureus and the effect on H. pylori strains. 16S rRNA identification was performed. Ten potential probiotic isolates were confirmed as belonging to the genera Lactobacillus and Pediococcus. All the strains were susceptible to clinical antibiotics, except to vancomycin. Sixty percent of the isolates exhibited antimicrobial activity against E. coli and S. aureus. The growth of H. pylori ATCC 43504 was suppressed by all the LAB, and the urease activity from all the H. pylori strains was inhibited, which may decrease its chances for survival in the stomach. The results suggest that LAB isolated from pulque and aguamiel could be an option to establish a harmless relationship between the host and H. pylori, helping in their eradication therapy.

scholarly journals Antiparasitic Drug Nitazoxanide Inhibits the Pyruvate Oxidoreductases of Helicobacter pylori, Selected Anaerobic Bacteria and Parasites, and Campylobacter jejuni

2006 ◽  
Vol 51 (3) ◽  
pp. 868-876 ◽  
Author(s):  
Paul S. Hoffman ◽  
Gary Sisson ◽  
Matthew A. Croxen ◽  
Kevin Welch ◽  
W. Dean Harman ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Campylobacter Jejuni ◽  
Trichomonas Vaginalis ◽  
Enzymatic Reaction ◽  
Anaerobic Bacteria ◽  
Spectral Shift ◽  
Thiamine Pyrophosphate ◽  
Escape Mutation ◽  
Thiazole Ring ◽  
H Pylori

ABSTRACT Nitazoxanide (NTZ) exhibits broad-spectrum activity against anaerobic bacteria and parasites and the ulcer-causing pathogen Helicobacter pylori. Here we show that NTZ is a noncompetitive inhibitor (Ki , 2 to 10 μM) of the pyruvate:ferredoxin/flavodoxin oxidoreductases (PFORs) of Trichomonas vaginalis, Entamoeba histolytica, Giardia intestinalis, Clostridium difficile, Clostridium perfringens, H. pylori, and Campylobacter jejuni and is weakly active against the pyruvate dehydrogenase of Escherichia coli. To further mechanistic studies, the PFOR operon of H. pylori was cloned and overexpressed in E. coli, and the multisubunit complex was purified by ion-exchange chromatography. Pyruvate-dependent PFOR activity with NTZ, as measured by a decrease in absorbance at 418 nm (spectral shift from 418 to 351 nm), unlike the reduction of viologen dyes, did not result in the accumulation of products (acetyl coenzyme A and CO2) and pyruvate was not consumed in the reaction. NTZ did not displace the thiamine pyrophosphate (TPP) cofactor of PFOR, and the 351-nm absorbing form of NTZ was inactive. Optical scans and 1H nuclear magnetic resonance analyses determined that the spectral shift (A 418 to A 351) of NTZ was due to protonation of the anion (NTZ−) of the 2-amino group of the thiazole ring which could be generated with the pure compound under acidic solutions (pKa = 6.18). We propose that NTZ− intercepts PFOR at an early step in the formation of the lactyl-TPP transition intermediate, resulting in the reversal of pyruvate binding prior to decarboxylation and in coordination with proton transfer to NTZ. Thus, NTZ might be the first example of an antimicrobial that targets the “activated cofactor” of an enzymatic reaction rather than its substrate or catalytic sites, a novel mechanism that may escape mutation-based drug resistance.

Sign in / Sign up

Export Citation Format

Share Document