Antibacterial action of bismuth in relation to Campylobacter pyloridis colonization and gastritis

In Vitro Susceptibility and Synergistic Effect of Bismuth Against Helicobacter pylori

Background/objectives: Bismuth is commonly used in Helicobacter pylori (H. pylori) eradication therapy. However, few studies have examined the in vitro susceptibility of H. pylori to bismuth. Moreover, the exact mechanism of action of bismuth on H. pylori remains unclear. The aim of this study was to identify the anti-bacterial effect of bismuth as well as to evaluate potential synergistic effects between bismuth and various antibiotics. Methods: The minimum inhibitory concentrations (MICs) of three bismuth preparations, bismuth subsalicylate, bismuth potassium citrate, and colloidal bismuth subcitrate (CBS, De-Nol) were determined for H. pylori strains using the agar dilution technique. Agar plates of varying pH values from 5.0 to 8.0 were used to investigate whether acidity influences the anti-bacterial effect of bismuth. A checkerboard assay was performed to assess the synergism between CBS and antibiotics (amoxicillin, clarithromycin, and metronidazole). Results: Twelve H. pylori strains, including three reference strains (H. pylori 26695, J99, and ATCC 43504), and nine clinically isolated strains were tested. The MICs for bismuth subsalicylate, bismuth potassium citrate, and CBS ranged from 4 to 32 μg/mL, 2 to 16 μg/mL, and 1 to 8 μg/mL, respectively. The bismuth MICs for the reference strains were similar at pH 5-8. In the checkerboard assay, no interactions between CBS and any of the antibiotics were observed in the reference H. pylori strains. Conclusions: Bismuth showed in vitro susceptibility against H. pylori. The enhanced eradication efficacy of bismuth-containing regimens appears to be due to mechanisms other than direct synergy with antibiotics.

Efficacy of bismuth for antibiotic-resistant Helicobacter pylori strains eradication: A systematic review and meta-analysis

BACKGROUND & AIMS

Antibiotic resistance of Helicobacter pylori (H. pylori) is increasing worldwide, and bismuth quadruple therapy has been recommended as a first-line regimen in many areas. This study aimed to investigate whether bismuth would improve the eradication rate (ER) of clarithromycin-/metronidazole-/levofloxacin-resistant H. pylori strains and how much additional efficacy bismuth could achieve.

METHODS

PubMed, EMBASE, Web of Science, and Cochrane Central databases for randomized controlled trials were systematically searched by two independent reviewers until 15 January 2022. Pooled ERs of clarithromycin-/metronidazole-/levofloxacin-resistant H. pylori strains were compared between bismuth-containing and non-bismuth therapies. Pooled risk ratios (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model.

RESULTS

Eight studies enrolling 340 individuals were included. The RRs of pooled ERs compared between bismuth-containing and non-bismuth therapies were 1.83 for clarithromycin-resistant strains (95% CI 1.16-2.89, pooled ER: 76.9% vs. 36.6%, p = .009, I²  = 0%), 1.39 for metronidazole-resistant strains (95% CI 1.09-1.78, pooled ER: 86.8% vs. 60.9%, p = .008, I²  = 37%), 2.75 for dual clarithromycin/metronidazole-resistant strains (95% CI 1.01-7.52, pooled ER: 76.9% vs. 18.2%, p = .05, I²  = 0%), and 1.04 for levofloxacin-resistant strains (95% CI 0.56-1.93, pooled ER: 63.4% vs. 54.3%, p = .90; I²  = 60%). Bismuth significantly increased the ERs of clarithromycin-, metronidazole-, and dual-resistant strains by 40%, 26%, and 59%, respectively. Subgroup analysis of treatment duration showed that the significantly higher eradication rate for antibiotic-resistant strains in bismuth-containing therapy than non-bismuth therapy was only observed in 14-day treatment regimens and not in 7-day regimens (p = .02 and .17, respectively).

CONCLUSIONS

Bismuth was most effective in improving the ERs of dual-resistant H. pylori strains, followed by clarithromycin- and metronidazole-resistant strains. Prolonged treatment duration might effectively improve the efficacy of bismuth in overcoming antibiotic resistance.

Bacterial Membrane Vesicles as a Novel Strategy for Extrusion of Antimicrobial Bismuth Drug in Helicobacter pylori

Bacterial antibiotic resistance is a major threat to human health. A combination of antibiotics with metals is among the proposed alternative treatments. Only one such combination is successfully used in clinics; it associates antibiotics with the metal bismuth to treat infections by Helicobacter pylori. This bacterial pathogen colonizes the human stomach and is associated with gastric cancer, killing 800,000 individuals yearly. The effect of bismuth in H. pylori treatment is not well understood in particular for sublethal doses such as those measured in the plasma of treated patients. We addressed this question and observed that bismuth induces the formation of homogeneously sized membrane vesicles (MVs) with unique protein cargo content enriched in bismuth-binding proteins, as shown by quantitative proteomics. Purified MVs of bismuth-exposed bacteria were strongly enriched in bismuth as measured by inductively coupled plasma optical emission spectrometry (ICP-OES), unlike bacterial cells from which they originate. Thus, our results revealed a novel function of MVs in bismuth detoxification, where secreted MVs act as tool to discard bismuth from the bacteria. Bismuth also induces the formation of intracellular polyphosphate granules that are associated with changes in nucleoid structure. Nucleoid compaction in response to bismuth was established by immunogold electron microscopy and refined by the first chromosome conformation capture (Hi-C) analysis of H. pylori. Our results reveal that even low doses of bismuth induce profound changes in H. pylori physiology and highlight a novel defense mechanism that involves MV-mediated bismuth extrusion from the bacteria and a probable local DNA protective response where polyphosphate granules are associated with nucleoid compaction.

Whole-genome sequencing and comparative analysis of Helicobacter pylori GZ7 strain isolated from China

Helicobacter pylori (H. pylori) is a Gram-negative pathogen as a carcinogen of the class Ι, with unique genetic diversity and wide geographic differences. The high incidence of gastric cancer in East Asia may be related to the bacterial genotype. It is of great significance that the genome of H. pylori in East Asia is widely collected. Therefore, we combined two sequencing technologies (PacBio and Illumina HiSeq 4000) and multiple databases to sequence and annotate the whole genome of H. pylori GZ7 isolated from a gastric cancer patient in Guizhou, China. Furthermore, this sequence was further compared with the genome sequence of 23 H. pylori strains isolated from different regions through collinearity comparison, specific gene analysis, phylogenetic tree construction, etc. The results showed that the genome of H. pylori GZ7 consists of 1,579,995 bp circle chromosomes with a GC content of 39.51%. This chromosome has 1,572 coding sequences, three antibiotic resistance genes, five prophages, and 198 virulence genes. The comparative genome analyses showed that H. pylori GZ7 has 53 specific genes compared to the other 23 strains. Most of these specific genes have not been annotated and characterized until now, whose research may provide insights into the biological activities of this strain. H. pylori GZ7 has the closest genetic relationship with H. pylori F30, and the farthest genetic relationship with H. pylori ELS37, which indicates that H. pylori genomes have geographical differences. This information may provide a molecular basis and guidance for constructing diagnostic methods for H. pylori and researching subsequent experiments.

Nickel, an essential virulence determinant of Helicobacter pylori: Transport and trafficking pathways and their targeting by bismuth

Metal acquisition and intracellular trafficking are crucial for all cells and metal ions have been recognized as virulence determinants in bacterial pathogens. Nickel is required for the pathogenicity of H. pylori. This bacterial pathogen colonizes the stomach of about half of the human population worldwide and is associated with gastric cancer that is responsible for 800,000 deaths per year. H. pylori possesses two nickel-enzymes that are essential for in vivo colonization, a [NiFe] hydrogenase and an abundant urease responsible for resistance to gastric acidity. Because of these two enzymes, survival of H. pylori relies on an important supply of nickel, implying tight control strategies to avoid its toxic accumulation or deprivation. H. pylori possesses original mechanisms for nickel uptake, distribution, storage and trafficking that will be discussed in this review. During evolution, acquisition of nickel transporters and specific nickel-binding proteins has been a decisive event to allow Helicobacter species to become able to colonize the stomach. Accordingly, many of the factors involved in these mechanisms are required for mouse colonization by H. pylori. These mechanisms are controlled at different levels including protein interaction networks, transcriptional, post-transcriptional and post-translational regulation. Bismuth is another metal used in combination with antibiotics to efficiently treat H. pylori infections. Although the precise mode of action of bismuth is unknown, many targets have been identified in H. pylori and there is growing evidence that bismuth interferes with the essential nickel pathways. Understanding the metal pathways will help improve treatments against H. pylori and other pathogens.

Helicobacter pylori infection: from standard to alternative treatment strategies

Helicobacter pylori is the major component of the gastric microbiome of infected individuals and one of the aetiological factors of chronic gastritis, peptic ulcer disease and gastric cancer. The increasing resistance to antibiotics worldwide has made the treatment of H. pylori infection a challenge. As a way to overhaul the efficacy of currently used H. pylori antibiotic-based eradication therapies, alternative treatment strategies are being devised. These include probiotics and prebiotics as adjuvants in H. pylori treatment, antimicrobial peptides as alternatives to antibiotics, photodynamic therapy ingestible devices, microparticles and nanoparticles applied as drug delivery systems, vaccines, natural products, and phage therapy. This review provides an updated synopsis of these emerging H. pylori control strategies and discusses the advantages, hurdles, and challenges associated with their development and implementation. An effective human vaccine would be a major achievement although, until now, projects regarding vaccine development have failed or were discontinued. Numerous natural products have demonstrated anti-H. pylori activity, mostly in vitro, but further clinical studies are needed to fully disclose their role in H. pylori eradication. Finally, phage therapy has the potential to emerge as a valid alternative, but major challenges remain, namely the isolation of more H. pylori strictly virulent bacterio(phages).

Three-Decade Failure to the Eradication of Refractory Helicobacter pylori Infection and Recent Efforts to Eradicate the Infection

BACKGROUND

Helicobacter pylori causes dangerous and deadly diseases such as gastric cancer and duodenal ulcers. Eradication and treatment of this bacterium are very important due to the deadly diseases caused by H. pylori and the high cost of treatment for countries.

METHODS

Thus, we present a complete list of the most important causes of failure in the treatment and eradication of H. pylori, and address new therapeutic methods that may be effective in controlling this bacterium in the future.

RESULTS

Many efforts have been made to control and eradicate this bacterium over the years, but no success has been achieved since its eradication is a complex process affected by the bacterial properties and host factors. Previous studies have shown that various factors are involved in the failure to eradicate H. pylori, such as new genotypes of the bacterium with higher pathogenicity, inappropriate patient cooperation, mutations, biofilm formation and dormant forms that cause antibiotic resistance, acidic stomach pH, high bacterial load, smoking, immunosuppressive features and intracellular occurrence of H. pylori. On the other hand, recent studies reported that the use of probiotics, nanoparticles, antimicrobial peptides, natural product and vaccines can be helpful in the treatment and eradication of H. pylori infections.

CONCLUSION

Eradication of H. pylori is crucial for the treatment of important diseases such as gastric cancer. Therefore, it seems that identifying the failure causes of treating this bacterium can be helpful in controlling the infections. Besides, further studies on new therapeutic strategies may help eradicate H. pylori in the future.

Bismuth salts with versus without acid suppression for Helicobacter pylori infection: A transmission electron microscope study

BACKGROUND

Bismuth oxychloride produced by interaction of bismuth compounds with gastric acid is believed to damage Helicobacter pylori. The effect of bismuth salts on H. pylori in the presence of strong acid suppression is unknown. This randomized trial aimed to determine effects of bismuth subcitrate on H. pylori with and without acid suppression.

METHODS

H. pylori -positive participants were allocated (1:1:1) to receive (a) no treatment (control), (b) colloidal bismuth subcitrate (CBS, 125 mg/tab), or (c) CBS plus high-dose proton-pump inhibitor (PPI), esomeprazole 40 mg q.i.d. for 3 days. In the treatment groups, CBS was given: 1 dose, 1 hour before endoscopy, 1 dose, 4 hours before endoscopy, or q.i.d. 24 hours before endoscopy. The study end-points were evaluated using transmission electron microscopy to observe the morphological changes of H. pylori in antral and corpus biopsies.

RESULTS

Twenty-seven H. pylori carriers were enrolled in this trial with qualitative end-points. In the no treatment group, active budding and replication of H. pylori were observed. In the CBS group, cellular swelling, vacuolization, structural degradation, and cell wall eruption of H. pylori were observed, with no apparent association with when the CBS was given. Among those receiving high-dose PPI-plus CBS or CBS only, there were no differences in number of H. pylori present or severity of bacterial damage whether CBS was given 1, 4, or 24 hours before endoscopy.

CONCLUSIONS

Based on direct morphological evaluation, the toxic effect of CBS treatment on H. pylori was demonstrated independent of acid suppression with PPI.

Helicobacteriology update

Helicobacter pylori colonises the gastric mucosa and is associated with various gastric diseases, including stomach cancer. At least 1 million new cases of stomach cancer cases are reported annually, and it is the fifth top cancer-killer in the world. Although H. pylori can be eradicated by a combination of antibiotics, the treatment success rate is declining due to the rise of antibiotic resistance. The same antibiotic combination must not be prescribed repeatedly. Susceptibility guided precision medicine is the most effective strategy to combat antibiotic resistant H. pylori cases. In addition, maintaining a stomach pH ≥6 during the antibiotic treatment is an important factor to increase cure rates. The new type of acid blocker, P-CABs, have shown promising results in H. pylori treatment. Natural products may suppress the H. pylori growth or relieve the symptoms but have not been successful in solving the root of the problem. New combination therapies show promise and the dream of 100% cure of the infection with minimal side effects from treatment seems achievable. The next decade will see combination therapies with newer acid blockers in widespread use at reasonable cost.

Bacteriophages of Helicobacter pylori

The bacterium Helicobacter pylori colonize the stomach in approximately half of the world’s population. Infection with this bacterium is associated with gastritis, peptic ulcer, adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Besides being a pathogen with worldwide prevalence, H. pylori show increasingly high antibiotic resistance rates, making the development of new therapeutic strategies against this bacterium challenging. Furthermore, H. pylori is a genetically diverse bacterium, which may be influenced by the presence of mobile genomic elements, including prophages. In this review, we analyze these issues and summarize various reports and findings related to phages and H. pylori, discussing the relationship between the presence of these elements and the genomic diversity, virulence, and fitness of this bacterium. We also analyze the state of the knowledge on the potential utility of bacteriophages as a therapeutic strategy for H. pylori.

Effect of bismuth subnitrate on in vitro growth of major mastitis pathogens

The mode of action of bismuth subnitrate in teat sealant formulations as a preventative for intramammary infections during the dry period is unknown. Although previous studies proposed an action mechanism-creating a physical barrier in the teat canal to prevent bacterial invasion-it has not been proven experimentally. We hypothesized that bismuth subnitrate has an inhibitory effect on bacterial growth, in addition to its barrier effect. The objective of this study was to assess the effect of bismuth subnitrate on bacterial growth of major mastitis-causing agents. A strain of Streptococcus uberis (SR115), 2 strains of Staphylococcus aureus (SA3971/59 and SA1), and a strain of Escherichia coli (P17.14291) were tested in vitro for their ability to grow in the presence or absence of bismuth subnitrate. Disk diffusion testing, impedance measurement, and evaluation of bacterial growth in shaking conditions were the methods used to test this hypothesis. A reduction of growth in the presence of bismuth subnitrate occurred for all the strains tested. However, we observed strain and species variations in the extent of growth inhibition. These results suggest that an inhibitory effect on bacterial growth by bismuth subnitrate could partially explain the efficacy of bismuth-based formulations for preventing intramammary infections over the dry period. Further research is required to test the effect of teat sealant formulations on bacterial growth.

Relating Phage Genomes to Helicobacter pylori Population Structure: General Steps Using Whole-Genome Sequencing Data

The review uses the Helicobacter pylori, the gastric bacterium that colonizes the human stomach, to address how to obtain information from bacterial genomes about prophage biology. In a time of continuous growing number of genomes available, this review provides tools to explore genomes for prophage presence, or other mobile genetic elements and virulence factors. The review starts by covering the genetic diversity of H. pylori and then moves to the biologic basis and the bioinformatics approaches used for studding the H. pylori phage biology from their genomes and how this is related with the bacterial population structure. Aspects concerning H. pylori prophage biology, evolution and phylogeography are discussed.

Role of Bismuth in the Eradication of Helicobacter pylori

Bismuth salts exert their activity within the upper gastrointestinal tract through action of luminal bismuth. Bismuth exerts direct bactericidal effect on Helicobacter pylori by different ways: forms complexes in the bacterial wall and periplasmic space, inhibits different enzymes, ATP synthesis, and adherence of the bacteria to the gastric mucosa. Bismuth also helps ulcer healing by acting as a barrier to the aggressive factors and increasing mucosal protective factors such as prostaglandin, epidermal growth factor, and bicarbonate secretion. To date, no resistance to bismuth has been reported. Also synergism between bismuth salts and antibiotics was present. It was shown that metronidazole and clarithromycin resistant H. pylori strains become susceptible if they are administered together with bismuth. Bismuth-containing quadruple therapy was recommended both by the Second Asia-Pacific Consensus Guidelines and by the Maastricht IV/Florence Consensus Report as an alternative first choice regimen to standard triple therapy, in areas with low clarithromycin resistance, and it is recommended as the first-line therapeutic option in areas with a high prevalence of clarithromycin resistance. Greater than 90% eradication success can be obtained by bismuth-containing quadruple therapy. Choosing bismuth as an indispensable part of first-line therapy is logical as both metronidazole and clarithromycin resistances can be overcome by adding bismuth to the regimen.

Efficacy and Safety of Wei Bi Mei, a Chinese Herb Compound, as an Alternative to Bismuth for Eradication of Helicobacter pylori

Bismuth-containing quadruple therapy has been recommended as the first line of treatment in areas of high clarithromycin or metronidazole resistance. However, safety concerns of bismuth agents have long been raised. We first assessed the efficacy and safety of Wei Bi Mei granules, which are bismuth compounds consisting of three synthetic drugs and five medicinal herbs, compared to bismuth aluminate and colloidal bismuth subcitrate (CBS) in H. pylori-infected mouse model. We then used atomic fluorescence spectroscopy and autometallography to measure the accumulation of three bismuth agents in the brain, heart, liver, and kidneys in adult Sprague-Dawley rats. We also evaluated the safety of bismuth agents by conducting clinical biochemistry tests in blood samples of experimental animals. Wei Bi Mei granules exhibited the highest efficacy of anti-H. pylori activity and yielded the lowest bismuth accumulation when compared to CBS and bismuth aluminate. Our findings show that Wei Bi Mei granules are a safe Chinese medicinal herb with potent anti-H. pylori activity and can be considered as an alternative to current bismuth compounds. Thus, Wei Bi Mei granules merit further evaluation, particularly with regard to efficacy and safety when they are combined with other H. pylori eradication medications in the clinical setting.

The antimicrobial spectrum of Xeroform®

INTRODUCTION/BACKGROUND

Xeroform^® is a petrolatum-based fine mesh gauze containing 3% bismuth tribromophenate. Bismuth, similar to other metals, has antimicrobial properties. Xeroform^® has been used for decades in burn and plastic surgery as a donor site dressing and as a covering for wounds or partial thickness burns. Despite this, the antimicrobial spectrum of Xeroform^® remains largely unknown. We examined the in-vitro efficacy of Xeroform^® against common burn pathogens using zone-of-inhibition methodology in a commercial research facility.

METHODS/DESIGN

Pure strains of 15 common burn pathogens including Methicillin-resistant Staphylococcus aureus (MRSA), Methicillin-sensitive Staphylococcus aureus (MSSA), Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterobacter cloacae, Escherichia coli, Candida albicans, Vancomycin resistant Enterococcus, Acinetobacter baumennii, Klebsiella pneumonia, Extended spectrum beta-lactamase producing Klebsiella, Beta hemolytic Streptococcus pyogenes, Proteus mirabilis, Serratia marcescens, and Salmonella enterica ssp. Enterica were inoculated at a strength of 10⁶-10¹⁰ CFU/ml onto appropriate agar plates. A sterile 1 in² Xeroform^® square was placed in the center of each plate, and the Zone of Inhibition (ZOI) was measured following 18-24h of incubation at 37°C. A second bismuth pharmaceutical (bismuth subsalicylate, Pepto-Bismol^®) was then tested using the same methodology against the same strains of MRSA, MSSA, E. coli, K. pneumonia and S. marcescens. Finally, 3% w/v bismuth tribromophenate in glycerol suspension was tested against 13 burn pathogens for antimicrobial activity independent of the Xeroform^® dressing by measure of Zone of Inhibition.

RESULTS/FINDINGS

For Xeroform^®, none of the fifteen pathogens had a measurable zone of inhibition on any plate. Bismuth subsalicylate showed a zone of inhibition for MSSA in 3 plates (mean of 47.2mm), in one of three plates for MRSA (13.8mm), and in one of three plates for S. marcesens (89.6mm). There was no zone of inhibition seen for K. pneumonia or E. coli. Bismuth tribromophenate, when not bound to Xeroform^® showed activity against 12 of 13 pathogens.

CONCLUSIONS/IMPLICATIONS

While bismuth subsalicylate, and bismuth tribromophenate unbound to Xeroform^® demonstrate antimicrobial activity, it appears that Xeroform^® dressings do not. The utility of Xeroform^® in burn medicine may relate more to use as an impervious dressing than to antimicrobial effect. Donor sites are clean surgical wounds and clean partial thickness burns may have minimal colonization present. In such circumstances, an inactive and impervious dressing may be all that is necessary to promote wound healing.

Therapeutic success with bismuth-containing sequential and quadruple regimens in Helicobacter pylori eradication

BACKGROUND AND STUDY AIMS

The success rate of Helicobacter pylori (H. pylori) eradication with the classical triple therapy is gradually declining. In this study, we aimed to compare and assess the efficacies of six different eradication regimens including sequential protocols.

PATIENTS AND METHODS

Endoscopically confirmed nonulcer dyspepsia patients were enrolled. H. pylori presence was determined either histologically or by a rapid urease test. Treatment-naive patients were randomly assigned to an either one of three 10-day (OAC, OTMB, and OACB) or one of three sequential protocols (OA+OCM, OA+OCMB, and OA+OMDB) (O=omeprazole, A=amoxicillin, C=clarithromycin, T=tetracycline, M=metronidazole, B=bismuth, D=doxycycline). The eradication was assessed 6-8weeks after the completion of the treatment by a 14C-urea breath test.

RESULTS

In total, 301 patients were included. Fifty-two percent of the participants (n=157) were female, and the mean age was 44.9years (range=18-70). The intention to treat (ITT) and per protocol (PP) eradication rate for each regimen is as follows: OAC (ITT=61.2%, PP=75%), OTMB (83.3%, 87%), OACB (76.5%, 79.6%), OA+OCM (72.3%, 73.9%), OA+OCMB (82.7%, 89.6%), and OA+OMDB (59.3%, 65.3%). Smoking significantly affected the eradication rate (P=0.04).

CONCLUSION

In this study, OTMB and OA+OCMB were significantly superior to the triple therapy and succeeded to reach the eradication rate proposed by the Maastricht consensus (over 80%). These two bismuth-containing regimens could be considered for first-line therapy in the regions with high clarithromycin resistance.

A Bacterial Cause of Cancer: An Historical Essay

This article reviews the history of the discovery of microbes that increase the risk of cancer of some tissues with a special emphasis on the bacterium Helicobacter pylori and the role played by two Australian physicians, neither schooled in research, who had open minds about the shibboleth that mycobacteria (acid-fast organisms) can survive the acid environment of the stomach, but that other pathogenic bacteria cannot. They discovered one of the most important human pathogens, Helicobacter pylori, and showed it capable of inducing severe gastric inflammatory disease. Subsequently, others built on their observations and showed it capable of inducing two gastric neoplasms: carcinoma and lymphoma. The Oncologist 2017;22:542-548.

Genomic structure and insertion sites of Helicobacter pylori prophages from various geographical origins

Helicobacter pylori genetic diversity is known to be influenced by mobile genomic elements. Here we focused on prophages, the least characterized mobile elements of H. pylori. We present the full genomic sequences, insertion sites and phylogenetic analysis of 28 prophages found in H. pylori isolates from patients of distinct disease types, ranging from gastritis to gastric cancer, and geographic origins, covering most continents. The genome sizes of these prophages range from 22.6–33.0 Kbp, consisting of 27–39 open reading frames. A 36.6% GC was found in prophages in contrast to 39% in H. pylori genome. Remarkably a conserved integration site was found in over 50% of the cases. Nearly 40% of the prophages harbored insertion sequences (IS) previously described in H. pylori. Tandem repeats were frequently found in the intergenic region between the prophage at the 3′ end and the bacterial gene. Furthermore, prophage genomes present a robust phylogeographic pattern, revealing four distinct clusters: one African, one Asian and two European prophage populations. Evidence of recombination was detected within the genome of some prophages, resulting in genome mosaics composed by different populations, which may yield additional H. pylori phenotypes.

Current status of Helicobacter pylori infection and evolution of treatment strategy in China

Infection with Helicobacter pylori (H. pylori) has become a common digestive disease and the prevalence of H. pylori infection remains high in the Chinese population. Recently, the Kyoto global consensus report on H. pylori gastritis and the Toronto consensus for the treatment of H. pylori infection in adults were issued. Therefore, it is essential to discuss the prevention and control of H. pylori infection in China. Due to severe resistance to antibiotics, toxic and host factors, the eradication rate in China has currently became lower than before. Therefore, whether to intervene H. pylori infection in the asymptomatic population and enlarge the indication for eradication and the cost-effect for this new strategy should be discussed. In addition, the implementation of the "test and treat" policy or not in China is debatable. Developing optimal treatment strategy has become a major challenge that clinicians face. This review focuses on the current H. pylori infection situation and the evolution of treatment strategies in China.

Eradication of Helicobacter pylori Infection

Helicobacter pylori infects about 50 % of the world's population, causing at a minimum chronic gastritis. A subset of infected patients will ultimately develop gastric or duodenal ulcer disease, gastric adenocarcinoma, or MALT (mucosa-associated lymphoid tissue) lymphoma. Eradication of H. pylori requires complex regimens that include acid suppression and multiple antibiotics. The efficacy of treatment using what were once considered standard regimens have declined in recent years, mainly due to widespread development of antibiotic resistance. Addition of bismuth to standard triple therapy regimens, use of alternate antibiotics, or development of alternative regimens using known therapies in novel combinations have improved treatment efficacy in specific populations, but overall success of eradication remains less than ideal. Novel regimens under investigation either in vivo or in vitro, involving increased acid suppression ideally with fewer antibiotics or development of non-antibiotic treatment targets, show promise for future therapy.

Genotyping of Peroxisome Proliferator-Activated Receptor gamma in Iranian Patients with Helicobacter pylori Infection

Helicobacter pylori (H. pylori) infection as a serious problem in both adults and children can induce chronic gastritis, peptic ulcer disease (PUD), and possibly gastric cancer. The aim of the current study was to survey antibiotic resistance and also to determine influence of PPARγ polymorphism in patients with H. pylori infection. During an 11-month-period, 98 H. pylori isolates were collected from 104 biopsy specimens. In vitro susceptibility of H. pylori isolates to 4 antimicrobial agents metronidazole, clarithromycin, amoxicillin and tetracycline were assessed by quantitative method according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guideline. PPARγ polymorphism was determined using polymerase chain reaction-restriction fragment length polymorphism assay. The frequency of H. pylori infection in our study was 94.2%. In vitro susceptibility data showed that highest level of resistance was related to metronidazole (66.3%), and the majority of H. pylori isolates were highly susceptible to amoxicillin and tetracycline (94.9% and 96.9%, respectively). Genotypic frequencies were 25.5% for CC (Pro12Pro), 40.8% for GC (Pro12Ala) and 33.7% for GG (Ala12Ala). In our study, CG genotype had highest distributions among infected patients with H. pylori. The study suggests that the PPAR-γ Pro12Ala polymorphism could be evaluated as a potential genetic marker for susceptibility to gastric cancer in the presence of H. pylori infection.

Role of bismuth in improving Helicobacter pylori eradication with triple therapy

In most regions of the world, antimicrobial resistance has increased to the point where empirical standard triple therapy for Helicobacter pylorieradication is no longer recommended. The treatment outcome in a population is calculated as the sum of the treatment success in the subpopulation with susceptible infections plus treatment success in the subpopulation with resistant infections. The addition of bismuth (i.e., 14-day triple therapy plus bismuth) can improve cure rates despite a high prevalence of antimicrobial resistance. The major bismuth effect is to add an additional 30%-40% to the success with resistant infections. The overall result is therefore dependent on the prevalence of resistance and the treatment success in the subpopulation with resistant infections (eg, with proton-pump inhibitor-amoxicillin dual therapy). Here, we explore the contribution of each component and the mechanisms of how bismuth might enhance the effectiveness of triple therapy. We also discuss the limitations of this approach and provide suggestions how triple therapy plus bismuth might be further improved.

Emerging Role of Probiotics in the Management of Helicobacter pylori Infection: Histopathologic Perspectives

BACKGROUND

There is growing evidence from preclinical and clinical studies that emphasizes the efficacy of probiotics in the management of Helicobacter (H) pylori infection; it increased the eradication rate, improved patient clinical manifestations and lowered treatment associated side effects.

AIM

In this review we documented the potential ability of probiotics to ameliorate H. pylori induced histological features.

MATERIALS AND METHODS

We searched the available literature for full length articles focusing the role of probiotics on H. pylori induced gastritis from histologic perspectives.

RESULTS

Probiotics lowered H. pylori density at the luminal side of epithelium, improved histological inflammatory and activity scores both in the gastric corpus and antrum. This effect persists for long period of time after discontinuation of probiotic supplementation and this is probably through an immune mechanism.

CONCLUSIONS

The current evidence support the promising role of probiotics in improving H. pylori induced histopathological features both in gastric antrum and corpus and for long periods of time. Because increased density of H. pylori on the gastric mucosa is linked to more severe gastritis and increased incidence of peptic ulcers, we can infer that a reduction of the density might help to decrease the risk of developing pathologies, probably the progression toward atrophic gastritis and gastric adenocarcinoma. These effects together with improving the H. pylori eradication rates and amelioration of treatment related side effects might open the door for probiotics to be added to H. pylori eradication regimens.

When Is Endoscopic Follow-up Appropriate After Helicobacter pylori Eradication Therapy?

The effect of Helicobacter pylori eradication treatment needs confirmation in patients with persistent symptoms and in those with complicated peptic ulcer. Endoscopic surveillance after eradication is needed in patients with advanced premalignant gastric lesions, previous early gastric cancer, gastric MALT lymphoma, and in those with a hereditary gastric cancer risk.

Glutathione and multidrug resistance protein transporter mediate a self-propelled disposal of bismuth in human cells

Glutathione and multidrug resistance protein (MRP) play an important role on the metabolism of a variety of drugs. Bismuth drugs have been used to treat gastrointestinal disorder and Helicobacter pylori infection for decades without exerting acute toxicity. They were found to interact with a wide variety of biomolecules, but the major metabolic pathway remains unknown. For the first time (to our knowledge), we systematically and quantitatively studied the metabolism of bismuth in human cells. Our data demonstrated that over 90% of bismuth was passively absorbed, conjugated to glutathione, and transported into vesicles by MRP transporter. Mathematical modeling of the system reveals an interesting phenomenon. Passively absorbed bismuth consumes intracellular glutathione, which therefore activates de novo biosynthesis of glutathione. Reciprocally, sequestration by glutathione facilitates the passive uptake of bismuth and thus completes a self-sustaining positive feedback circle. This mechanism robustly removes bismuth from both intra- and extracellular space, protecting critical systems of human body from acute toxicity. It elucidates the selectivity of bismuth drugs between human and pathogens that lack of glutathione, such as Helicobacter pylori, opening new horizons for further drug development.

Antimicrobial activity of bismuth subsalicylate on Clostridium difficile, Escherichia coli O157:H7, norovirus, and other common enteric pathogens

Previous studies have shown bismuth subsalicylate (BSS) has antimicrobial properties, but few studies have addressed the mechanism of action. Furthermore, following BSS ingestion other bismuth salts form throughout the gastrointestinal tract including bismuth oxychloride (BiOCl) that also act upon enteric pathogens. To further understand the antimicrobial activity of bismuth in infectious diarrhea, the antimicrobial effect of BSS and BiOCl on Clostridium difficile, Salmonella, Shigella, Shiga toxin-producing Escherichia coli strains and norovirus (NoV) were measured. Bacterial enteric pathogens in pure culture or in human fecal material were exposed to 35mg/ml BSS or BiOCl with or without a vehicle suspension. BSS and BiOCl treated samples were quantified and visualized by transmission electron microscopy. To measure the effect on NoV, reduction of infectious murine NoV (MNV), a surrogate for human NoV, and Norwalk virus RNA levels were measured by viral plaque assay and RT-qPCR, respectively. BSS and BiOCl reduced bacterial growth by 3-9 logs in all strains with majority resulting in populations of <10 cfu/ml within 24 h. Similar results were found when fecal material was included. Microscopy images detected bismuth on bacterial membranes and within the bacterial organisms at 30 min post-treatment. At 8.8mg/ml BSS and BiOCl reduced infectivity of MNV significantly by 2.7 and 2.0 log after 24 h of exposure. In addition, both BSS and BiOCl slightly reduced the level of Norwalk replicon-bearing cells suggesting that bismuth may inhibit NoV in vivo. Collectively, our results confirm and build on existing data that BSS has antimicrobial properties against a wide-range of diarrhea-causing pathogens.

Helicobacter pylori: perspectives and time trends

The discovery of Helicobacter pylori three decades ago is a modern medical success story. It markedly changed our understanding of the pathophysiology of gastroduodenal diseases and led to an improvement in the treatment of diseases related to H. pylori infection. Many of these diseases (such as ulcer disease and mucosal associated lymphoid tissue lymphoma) have become curable, and others (gastric cancer) might be preventable with the application of H. pylori eradication therapy. Since its discovery, H. pylori has also been identified as a trigger for some extragastric diseases. Promising results in this exciting field might have a clinical effect in the near future. This Timeline gives an overview of the success of clinical research on H. pylori to date and highlights some future trends in this area.

Lactobacillus reuteri in management of Helicobacter pylori infection in dyspeptic patients: a double-blind placebo-controlled randomized clinical trial

INTRODUCTION

The eradication rate of Helicobacter pylori following the standard triple therapy is declining. This study was conducted to test whether the addition of Lactobacillus reuteri to the standard triple therapy improves the eradication rates as well as the clinical and pathological aspects in H. pylori infection.

METHODS

A total of 70 treatment-naïve patients were randomly assigned into group A (the L. reuteri treated group) and group B (the placebo control group). Patients were treated by the standard triple therapy for 2 weeks and either L. reuteri or placebo for 4 weeks. They were examined by symptom questionnaire, H. pylori antigen in stool, upper endoscopy with biopsies for rapid urease test and histopathological examination before treatment and 4 weeks after treatment.

RESULTS

The eradication rate of H. pylori infection was 74.3% and 65.7% for both L. reuteri and placebo treated groups, respectively. There was a significant difference regarding the reported side effects, where patients treated with L. reuteri reported less diarrhea and taste disorders than placebo group. A significant difference within each group was observed after treatment regarding Gastrointestinal Symptom Rating Scale (GSRS) scores; patients treated with L. reuteri showed more improvement of gastrointestinal symptoms than the placebo treated group. The severity and activity of H. pylori associated gastritis were reduced after 4 weeks of therapy in both groups. The L. reuteri treated group showed significant improvement compared with the placebo treated group.

CONCLUSION

Triple therapy of H. pylori supplemented with L. reuteri increased eradication rate by 8.6%, improved the GSRS score, reduced the reported side effects and improved the histological features of H. pylori infection when compared with placebo-supplemented triple therapy.

Isolation and characterization of bacteriophages of Helicobacter pylori isolated from Egypt

Aim: The aim of this work was to isolate and characterize bacteriophages from wastewater for the pathogenic bacteria Helicobacter pylori. Materials & methods: In this study, we isolated and characterized two phages against H. pylori isolated from gastric biopsies. The specific phages were isolated by the single plaque isolation technique, propagated by the liquid enrichment method and purified by the polyethylene glycol–dextran sulfate two-phase system. Results: The phages were designated as φHPE1 and φHPE2; φHPE1 had a head with a diameter of approximately 62 nm and short noncontractile tail with a length and width of approximately 12 × 6 nm and φHPE2 had an isometric head with a diameter of approximately 92.5 nm and a tail with a length of approximately 180 nm and width of approximately 15 nm. The host ranges were investigated with four strains of Helicobacter and all strains were susceptible to either φHPE1 or φHPE2. Conclusion: These results suggest that it may be possible to use this phage to control the disease caused by H. pylori.

Microbial community biogeographic patterns in the rhizosphere of two Brazilian semi-arid leguminous trees

Arid environments are regular and well distributed over all continents and display drought characteristics whether full-time or seasonal. This study aims to characterize how the microbial communities of the rhizosphere of two leguminous trees from the Brazilian semi-arid biome the Caatinga are geographically and seasonally shaped, as well as the factors driving this variation. With that purpose, the soil rhizosphere from two leguminous trees (Mimosa tenuiflora and Piptadenia stipulacea (Benth.) Ducke) were sampled in two different seasons: rainy and drought at five different sites. Assessment of bacterial and archaeal communities occurred by T-RFLP analysis of 16S rRNA and archaeal amoA genes. By these means, it was observed that the seasons (wet and dry periods) are the factors that most influence the composition of the microbial community from both analyzed plants, except for the results obtained from the CCA applied to Archaeas. Furthermore, soil physical-chemical factors also had a significant influence on the community and indicated a geographical pattern of the bacterial community. It was not possible to observe significant modifications in the composition in relation to the plant species. We have seen that soil characteristics and rainfall were the factors that most influenced the microbial composition. Also, the bacterial community had a significant correlation with soil characteristics that indicates that these rhizosphere communities might be selected by environmental characteristics. Furthermore, the data suggest that climate plays a key role in structuring the microbial community of this biome.

Review article: bismuth-based therapy for Helicobacter pylori eradication in children

BACKGROUND

Because of the decrease in the Helicobacter pylori eradication rate after standard triple therapy with a proton pump inhibitor and two antibiotics, bismuth-based therapy has recently been recommended as alternate first-line regimen in children.

AIM

To comprehensively review the clinical, pharmacologic and microbiologic properties of bismuth salts, and to summarise the evidence for the therapeutic efficacy of bismuth-based therapy for H. pylori eradication in children.

METHODS

Bibliographical searches were performed in MEDLINE. Results on the efficacy of bismuth-containing regimens on H. pylori eradication were combined using the inverse variance method.

RESULTS

Bismuth monotherapy showed a very low efficacy. Overall, the mean eradication rate with bismuth-based dual therapy was 68% (95% CI, 60-76%) (intention-to-treat analysis-ITT) and 73% (95% CI, 64-81%) (per protocol-PP). In case series, the overall percentages of children with successful eradication for triple therapy containing bismuth were 82% (95% CI, 76-88%) and 86% (95% CI, 80-92%) according to ITT and PP respectively. In comparative studies, H. pylori eradication rates ranged between 69% and 85% according to ITT and between 74% and 96% PP. Side effects included dark stools, urine discoloration, black tongue, burning tongue, and marked darkness of the gums.

CONCLUSIONS

The evidence in favour of bismuth compounds for treating infected children is still not clear. Well-designed, randomised, multi-centre studies of H. pylori eradication trials in children comparing bismuth-based triple therapy with the best available recommended first-line therapies are needed. The evidence obtained from audited case series that produce an eradication rate of >95% on PP analysis should also be considered.

Alternative therapies for Helicobacter pylori: probiotics and phytomedicine

Helicobacter pylori is a common human pathogen infecting about 30% of children and 60% of adults worldwide and is responsible for diseases such as gastritis, peptic ulcer and gastric cancer. Treatment against H. pylori is based on the use of antibiotics, but therapy failure can be higher than 20% and is essentially due to an increase in the prevalence of antibiotic-resistant bacteria, which has led to the search for alternative therapies. In this review, we discuss alternative therapies for H. pylori, mainly phytotherapy and probiotics. Probiotics are live organisms or produced substances that are orally administrated, usually in addition to conventional antibiotic therapy. They may modulate the human microbiota and promote health, prevent antibiotic side effects, stimulate the immune response and directly compete with pathogenic bacteria. Phytomedicine consists of the use of plant extracts as medicines or health-promoting agents, but in most cases the molecular mode of action of the active ingredients of these herbal extracts is unknown. Possible mechanisms include inhibition of H. pylori urease enzyme, disruption of bacterial cell membrane, and modulation of the host immune system. Other alternative therapies are also reviewed.

Genome sequencing reveals a phage in Helicobacter pylori

Helicobacter pylori chronically infects the gastric mucosa in more than half of the human population; in a subset of this population, its presence is associated with development of severe disease, such as gastric cancer. Genomic analysis of several strains has revealed an extensive H. pylori pan-genome, likely to grow as more genomes are sampled. Here we describe the draft genome sequence (63 contigs; 26× mean coverage) of H. pylori strain B45, isolated from a patient with gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The major finding was a 24.6-kb prophage integrated in the bacterial genome. The prophage shares most of its genes (22/27) with prophage region II of Helicobacter acinonychis strain Sheeba. After UV treatment of liquid cultures, circular DNA carrying the prophage integrase gene could be detected, and intracellular tailed phage-like particles were observed in H. pylori cells by transmission electron microscopy, indicating that phage production can be induced from the prophage. PCR amplification and sequencing of the integrase gene from 341 H. pylori strains from different geographic regions revealed a high prevalence of the prophage (21.4%). Phylogenetic reconstruction showed four distinct clusters in the integrase gene, three of which tended to be specific for geographic regions. Our study implies that phages may play important roles in the ecology and evolution of H. pylori.

IMPORTANCE

Helicobacter pylori chronically infects the gastric mucosa in more than half of the human population, and while most of the infected individuals do not develop disease, H. pylori infection doubles the risk of developing gastric cancer. An abundance and diversity of viruses (phages) infect microbial populations in most environments and are important mediators of microbial diversity. Our finding of a 24.6-kb prophage integrated inside an H. pylori genome and the observation of circular integrase gene-containing DNA and phage-like particles inside cells upon UV treatment demonstrate that we have discovered a viable H. pylori phage. The additional finding of integrase genes in a large proportion of screened isolates of diverse geographic origins indicates that the prevalence of prophages may have been underestimated in H. pylori. Since phages are important drivers of microbial evolution, the discovery should be important for understanding and predicting genetic diversity in H. pylori.

Comparison of azithromycin and metronidazole in a quadruple-therapy regimen for Helicobacter pylori eradication in dyspepsia

BACKGROUND/AIM

Helicobacter pylori (H pylori) plays an important role in the pathogenesis of chronic gastritis, peptic ulcer disease, and gastric neoplasms . Therefore, it is necessary to select an effective regimen for H pylori eradication . The aim of this study was to compare the efficacy of two quadruple-therapy regimens-one with azithromycin and the other with metronidazole-for H pylori eradication in patients with dyspepsia.

MATERIALS AND METHODS

In this double-blind randomized clinical trial conducted in Rasoule-Akram Hospital in 2006, we included 60 patients (aged 15-70 years) who had dyspepsia and H pylori infection as diagnosed by upper gastrointestinal endoscopy and rapid urease test. Patients were randomly assigned to receive a quadruple-therapy regimen for 2 weeks: 1) the MAO-B group (n = 30) received metronidazole 500 mg b.i.d, amoxicillin 1g b.i.d, omeprazole 20 mg b.i.d, and bismuth 240 mg b.i.d and 2) the AAO-B group (n = 30) received azithromycin 500 mg once daily for 1 week and amoxicillin 1g b.i.d, omeprazole 20 mg b.i.d, and bismuth 240 mg b.i.d for 2 weeks). H pylori eradication was assessed by the rapid urease test (RUT) 2 months after the cessation of treatment .

RESULTS

H pylori was eradicated in 68% and 69% of patients in the MAO-B and AAO-B groups, respectively. There was no significant difference in H pylori eradication rates between the two groups (P = 0.939).

CONCLUSION

No significant difference exists between the two quadruple-therapy regimens that were tested.

The history of Helicobacter pylori: a reflection on the relationship between the medical community and industry

The paper deals with a viewpoint on the relationship between the drug industry and the medical world taking inspiration from the history of the discovery of Helicobacter pylori as a pathogenic agent in peptic disease.

Is GastroPanel serum assay useful in the diagnosis of Helicobacter pylori infection and associated gastritis in children?

GastroPanel (Biohit, Helsinki, Finland) is a serum test kit that measures Helicobacter pylori antibodies (HPABs) and pepsinogens I and II and gastrin 17, which reflect the degree of atrophic gastritis. We assessed whether GastroPanel can replace endoscopic biopsies in the diagnostics of H. pylori in children and whether the H. pylori-infected children show markers for atrophic gastritis. Eighty children (median age, 6.8 years; range, 0.6-18.7 years) underwent gastroscopy for H. pylori-related abdominal complaints (n = 40), surveillance after surgery for gastrointestinal tract malformations (n = 20), gastroesophageal reflux (GER) (n = 10), and miscellaneous diseases (n = 10). Gastric biopsies and a serum sample were obtained from all 80 children. HPAB levels of 38 and 15 IU were tested as cutoff values for H. pylori gastritis. The biopsies showed H. pylori-positive gastritis in 30 children, 9 had gastritis not associated with H. pylori, and 41 had normal biopsies. Atrophic gastritis was not found. The sensitivity and specificity of HPAB for H. pylori were 47% and 98% (cutoff, 38 IU), and 73% and 85% (cutoff, 15 IU), respectively. The assays of pepsinogens and gastrin did not improve sensitivity. None of the markers of pepsinogen (PG) I, PGII, and gastrin 17 (G17) indicated atrophic gastritis. GastroPanel is too insensitive for H. pylori screening and does not replace endoscopy. Markers indicative of atrophic gastritis were negative in all children with H. pylori gastritis.

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori infection

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.

Metabolism of bismuth subsalicylate and intracellular accumulation of bismuth by Fusarium sp. strain BI

Enrichment cultures were conducted using bismuth subsalicylate as the sole source of carbon and activated sludge as the inoculum. A pure culture was obtained and identified as a Fusarium sp. based on spore morphology and partial sequences of 18S rRNA, translation elongation factor 1-alpha, and beta-tubulin genes. The isolate, named Fusarium sp. strain BI, grew to equivalent densities when using salicylate or bismuth subsalicylate as carbon sources. Bismuth nitrate at concentrations of up to 200 muM did not limit growth of this organism on glucose. The concentration of soluble bismuth in suspensions of bismuth subsalicylate decreased during growth of Fusarium sp. strain BI. Transmission electron microscopy and energy-dispersive spectroscopy revealed that the accumulated bismuth was localized in phosphorus-rich granules distributed in the cytoplasm and vacuoles. Long-chain polyphosphates were extracted from fresh biomass grown on bismuth subsalicylate, and inductively coupled plasma optical emission spectrometry showed that these fractions also contained high concentrations of bismuth. Enzyme activity assays of crude extracts of Fusarium sp. strain BI showed that salicylate hydroxylase and catechol 1,2-dioxygenase were induced during growth on salicylate, indicating that this organism degrades salicylate by conversion of salicylate to catechol, followed by ortho cleavage of the aromatic ring. Catechol 2,3-dioxygenase activity was not detected. Fusarium sp. strain BI grew with several other aromatic acids as carbon sources: benzoate, 3-hydroxybenzoate, 4-hydroxybenzoate, gentisate, d-mandelate, l-phenylalanine, l-tyrosine, phenylacetate, 3-hydroxyphenylacetate, 4-hydroxyphenylacetate, and phenylpropionate.

The action of bismuth against Helicobacter pylori mimics but is not caused by intracellular iron deprivation

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 (MIC(CBS)). Similar morphologic and outer membrane changes were observed following growth in iron-limiting medium and at the MIC(CBS) 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 MIC(CBS) 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.

The effect of antibiotics and bismuth on fecal hydrogen sulfide and sulfate-reducing bacteria in the rat

Colonic bacteria produce the highly toxic thiol, hydrogen sulfide. Despite speculation that this compound induces colonic mucosal injury, there is little information concerning manipulations that might reduce its production. We studied the effect of antibiotics and bismuth on the production of hydrogen sulfide in rats. Baseline fecal samples were analyzed for hydrogen sulfide concentration and release rate during incubation and numbers of sulfate-reducing bacteria. Groups of six rats received daily doses of ciprofloxacin, metronidazole, or sulfasalazine for one week, and feces were reanalyzed. Bismuth subnitrate was then added to the antibiotic regimens. While sulfide production and sulfate-reducing bacteria were resistant to treatment with ciprofloxacin or metronidazole, bismuth acted synergistically with ciprofloxacin to inhibit sulfate-reducing bacteria growth and to reduce sulfide production. Combination antibiotic-bismuth therapy could provide insights into the importance of sulfide and sulfate-reducing bacteria in both human and animal models of colitis and have clinical utility in the treatment of antibiotic-resistant enteric pathogens.

Favourable effect of regular intake of fermented milk containing Lactobacillus johnsonii on Helicobacter pylori associated gastritis

BACKGROUND

Lactobacillus johnsonii (Lj1) had an in vitro and in vivo inhibitory effect on Helicobacter pylori. Fermented milk containing Lj1 (LC1), coadministered with antibiotics had a favourable effect on H. pylori gastritis.

AIM

Evaluate the effect of LC1 intake without antibiotics on H. pylori gastritis.

METHODS

Fifty H. pylori positive healthy volunteers were randomised in a double-blind study to LC1 or placebo. Gastric biopsies from the antrum and corpus were obtained before, and after 3 and 16 weeks of treatment, for histology and quantitative cultures.

RESULTS

Severity and activity of antral gastritis was reduced after 16-week LC1 intake (pretreatment and 16-week inflammatory cell score: 6.0 +/- 0.8 vs. 5.3 +/- 0.1; P=0.04). H. pylori density decreased in the antrum after LC1 intake (3-week: 4.4 +/- 0.6; 16-week: 4.3 +/- 0.5 log10 colony forming units (cfu) vs. pretreatment 4.5 +/- 0.4 log10 cfu; P=0.04, respectively). Mucus thickness increased after 16 weeks of LC1 consumption (change of mucus thickness with LC1 and placebo in the antrum: 0.6 +/- 1.3 vs. -0.2 +/- 1.0, P=0.01; in the corpus: 0.3 +/- 1.1 vs. -0.6 +/- 1.5, P=0.03).

CONCLUSION

LC1 intake had a favourable, albeit weak, effect on H. pylori associated gastritis, particularly in the antrum. Regular ingestion of fermented milk containing L. johnsonii may reduce the risk of developing disorders associated with high degrees of gastric inflammation and mucus depletion.

Eradication of Helicobacter pylori: current perspectives

Helicobacter pylori appears to be a necessary cofactor for the majority of non-drug-associated duodenal and gastric ulcers. H. pylori infection is a chronic and transmissible infectious disease whose eradication has proved difficult. The last decade has seen > 1000 clinical trials using different eradication regimens. Many of these trials had severe limitations, some of which will be discussed here. The current review also focuses on the regimens that were used in the past, the present regimens and possibilities for the future. Also highlighted are some other aspects of H. pylori management, such as eradication failures and drug resistance.

One-week triple vs. quadruple therapy for Helicobacter pylori infection - a randomized trial

BACKGROUND

Seven-day triple therapy including omeprazole, clarithromycin and amoxicillin has become the treatment of choice for Helicobacter pylori infection. However, 7 days of classical quadruple therapy combining omeprazole, tetracycline, metronidazole and bismuth may be an alternative to triple therapy.

AIM

To compare triple vs. quadruple therapy for H.pylori eradication.

METHODS

Three hundred and thirty-nine patients with peptic ulcer and H. pylori infection were included in the study. Patients were randomized to receive omeprazole, 20 mg, amoxicillin, 1 g, and clarithromycin, 500 mg, all b.d., or omeprazole, 20 mg b.d., tetracycline chloride, 500 mg, metronidazole, 500 mg, and bismuth subcitrate, 120 mg, all t.d.s. Cure was defined as a negative urea breath test at least 2 months after treatment.

RESULTS

Per protocol and intention-to-treat cure rates were 86%[95% confidence interval (CI), 80-91%] and 77% (95% CI, 70-83%) for triple therapy, and 89% (95% CI, 82-93%) and 83% (95% CI, 76-88%) for quadruple therapy. No significant differences between the groups were found in the cure rates, compliance or side-effects.

CONCLUSION

One-week triple and quadruple therapy show similar results when used as first-line eradication treatment.