Strategies used by helicobacter pylori to establish persistent infection

Helicobacter pylori(H. pylori) is a Gram-negative and motile bacterium that colonizes the hostile microniche of the human stomach, then persists for the host's entire life, if not effectively treated. Clinically, H. pylori plays a causative role in the development of a wide spectrum of diseases including chronic active gastritis, peptic ulceration, gastric adenocarcinoma, and gastric mucosaassociated lymphoid tissue lymphoma. Due to the global distribution of H. pylori, it is no exaggeration to conclude that smart strategies are contributing to adaptation of the bacterium to its permanent host. Thirty-four years after the discovery of this bacterium, there are still many unanswered questions. For example, which strategies help the bacterium to survive in this inhospitable microniche? This question is slightly easier to answer if we presume the same clinical concept for both persistent infection and disease. Understanding the mechanisms governing H. pylori persistence will improve identification of the increased risk of diseases such as gastric cancer in patients infected with this bacterium. A well-defined and longterm equilibrium between the human host and H. pylori allows bacterial persistence in the gastric microniche; although this coexistence leads to a high risk of severe diseases such as gastric cancer. To escape the bactericidal activity of stomach acid, H. pylori secretes large amounts of surface-associated and cytosolic urease. The potential to avoid acidic conditions and immune evasion are discussed in order to explain the persistence of H. pylori colonization in the gastric mucosa, and data on bacterial genetic diversity are included. Information on the mechanisms related to H. pylori persistence can also provide the direction for future research concerning effective therapy and management of gastroduodenal disorders. The topics presented in the current review are important for elucidating the strategies used by H. pylori to help the bacterium persist in relation to the immune system and the many unfavorable features of living in the gastric microniche.

Vaccine against Helicobacter pylori : Inevitable approach

Over three decades have passed since the discovery of Helicobacter pylori(H. pylori), and yet many questions about its treatment remain unanswered. For example, there is no certainty regarding continued use of current antibiotic therapy against H. pylori. The bad news is that even combined regimens are also unable to eradicate bacterial colonization. The worst problem with H. pylori chemotherapy is that even if we identify the most successful regimen, it cannot eliminate the risk of re-infection. This problem is further complicated by the fact that clinicians have no information as to whether probiotics are useful or not. Moreover, to date, we have no large scale produced vaccine effective against H. pylori. Due to the relatively rapid and abundant dissemination of guidelines globally reported concerning management of gastric cancer prevention and therapeutic regimens, clinicians may choose a vaccine as better effective weapon against H. pylori. Therefore, a radical shift in adopted strategies is needed to guide ultimate decisions regarding H. pylori management. In light of failures in vaccine projects, we should identify better vaccine design targeting conserved/essential genes. The unique character and persistence of H. pylori pose obstacles to making an effective vaccine. Preferably, in developing countries, the best reasonable and logical approach is to recommend prophylactic H. pylori vaccine among children as an obligatory national program to limit primary colonization. Trying to produce a therapeutic vaccine would be postponed until later. In reality, we should not forget to prescribe narrow spectrum antibiotics. In the current review, I draw a route to define the best adopted strategy against this rogue bacterium.

Resistance to clarithromycin and gastroenterologist's persistence roles in nomination for Helicobacter pylori as high priority pathogen by World Health Organization

Due to the increasing prevalence of clarithromycin resistance, future of management of Helicobacter pylori(H. pylori) infections need to be recognized. To now, clarithromycin was the best effective, well-tolerated and safe antibiotic used in treatment of the bacterium, but, increasing trend of resistance reduced efficacy of recommended regimens. Indeed, gastroenterologists are mostly unable to start appropriate therapyaccording to the sensitivity profile-due to the certain difficulties in routine H. pylori culture procedure and being time consuming method. This announcement by World Health Organization(WHO) was an onset to reconsider current challenging dilemma about H. pylori clarithromycin resistant isolates. Therefore, investigating of various factors affecting this nomination by WHO is highly welcomed. In fact, WHO enumerated more than 16 pathogens which seriously threats human life and public health, thus better management or effective guidelines are necessary. Here for the first time, we nominated this phenomenon as ‘‘gastroenterologist's persistence'' which should be equally investigated as antibiotic resistance. The ability of gastroenterologists to win the game against H. pylori infections is highly influenced by their collaboration with diagnostic laboratories to apply susceptibility patterns before any prescription. In conclusion, closer collaboration between two important partners(gastroenterologists and microbiologists) in management of H. pylori infection may hopefully trigger an era to remedy current crisis in clarithromycin resistance, a later gastric cancer can be practically preventable.

Role of dup A in virulence of Helicobacter pylori

Helicobacter pylori(H. pylori) is a gastric human pathogen associated with acute and chronic gastritis, 70% of all gastric ulcers, 85% of all duodenal ulcers, and both forms of stomach cancer, mucosal-associated lymphoid tissue(MALT) lymphoma and adenocarcinoma. Recently, attention has focused on possible relationship between presence of certain virulence factor and H. pylori-associated diseases. Some contradictory data between this bacterium and related disorders has been observed since not all the colonized individuals develop to severe disease. The reported diseases plausibility related to H. pylori specific virulence factors became an interesting story about this organism. Although a number of putative virulence factors have been identified including cytotoxin-associated gene a(cag A) and vac A, there are conflicting data about their actual participation as specific risk factor for H. pylori-related diseases. Duodenal ulcer promoting gene a(dup A) is a virulence factor of H. pylori that is highly associated with duodenal ulcer development and reduced risk of gastric cancer. The prevalence of dup A in H. pylori strains isolated from western countries is relatively higher than in H. pylori strains from Asian countries. Current confusing epidemiological reports will continue unless future sophisticated and molecular studies provide data on functional and complete dup A cluster in H. pylori infected individuals. This paper elucidates available knowledge concerning role of dup A in virulence of H. pylori after a decade of its discovery.

Chinese Helicobacter pylori vaccine: Solution for an old challenge?

Helicobacter pylori(H. pylori) is an important cause for gastric cancer in high risk individuals. H. pylori colonizes more than 50% of the world's population and associated peptic ulcer disease and gastric malignancy have important public health implications. It has been classified as a class Ⅰ carcinogen in 1994 by the World Health Organization. Clinicians are often prompted to eliminate the infection the moment it is detected. This also, unfortunately, led to reckless use of antibiotics and reports of increasing resistance are now worldwide. Each year, many of people die from gastric cancer; thus application of effective vaccine can reduce this relatively high mortality worldwide. H. pylori can be eliminated by antibiotics but efficacy is sharply decreasing. Moreover, current therapy is also expensive and with side effects. Vaccine may be the best solution to the above problem but there are many challenges in producing such an effective therapeutic vaccine. Recently, the Chinese group published in Lancet, a single-center, randomized, phase Ⅲ study of an oral recombinant vaccine(Urease B subunit fused with heat-labile enterotoxin B derived from Escherichia coli) prescribed in the Chinese children(6-15 years) without a history of H. pylori infection. This review provides an insight into this new solution for an old challenge.

Association of inducible nitric oxide synthetase genotype and Helicobacter pylori infection gastric cancer risk may be due to faulty primer design

Rafiei et al recently described an association between the presence of the C150T polymorphism of the induc-ible nitric oxide synthase(iNOS)gene and Helicobacter pylori(H.pylori)induced gastric cancer.When we used primer-BLAST to find the polymerase chain reaction (PCR)product that would be generated by the primers used by these authors no products against any of the sequences present in the GenBank database were found.Further analysis of the iNOS sequences present in the GenBank suggest that the result from their study might come from a faulty primer design and may thus represent an artifact.Alternatively they may be correct and have identified a truly interesting explanation for the mechanism whereby H.pylori induces gastric cancer but some additional experiments would be in order to exclude the possibility of a PCR artifact.

Fecal microbiota transplantation against irritable bowel syndrome?Rigorous randomized clinical trials are required

Halkj?r et al searched systematically nine articles including 48 patients, and concluded that fecal microbiota transplantation(FMT) can be an ideal treatment option for irritable bowel syndrome(IBS) subjects. Regardless of the few successes in current traditional therapies(change in diet, herbal medicine and antibiotics) in IBS, a sharp increase in interests in the FMT option has been reported in the current century. However, there is a long list of unclear issues concerning the application of FMT for the treatment of IBS. Route of delivery and optimum dosage are the major concerns to consider before using in clinical practice.

Lack of evidence for Helicobacter pylori to prevent children growth efficiently

We have read with great interest an article by Kocaoglu et al published in May issue of the World Journal of Pediatrics.[1]A total of 243 children aged between 8-18 years were examined based on growth determinants and existence of Helicobacter pylori(H.pylori)colonization in Turkey.The conclusion of this research is that H.pylori colonization affected children growth;and the longer duration of infection,the worse effect on growth.