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

The study of Helicobacter pylori genetic variability brought us interesting data on the history of mankind. Based on multilocus sequence typing and more recently on whole-genome sequencing, paleomicrobiology still attracts the attention of global researchers in relation to its ancestor roots and coexistence with humans. Three studies determining the prevalence of virulence factors illustrates the controversial results obtained since 30 years by studies trying to associate prevalence of different virulence markers and clinical outcomes of H. pylori infection. Three articles analyzed the prevalence and risk of multiple (genetically distinct isolates) and mixed (susceptible and resistant isolates) infections. A number of studies confirm that H. pylori prevalence is falling worldwide especially in the developed world and in children but that the level of infection is higher in certain ethnic minorities and in Migrants. There is little new in identifying the mode of H. pylori transmission though intrafamilial spread appears to be important. There have, however, been some interesting papers on the presence of the organism in food, water, and the oral cavity.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/hel.12514

Epidemiology of Helicobacter pylori Infection

Approximately 50% (over 3 billion) of the world populations are known to be infected with Helicobacter pylori , mainly in the developing countries . Among those, hundreds of millions of people develop peptic ulceration during their lifetime and still tens of millions might progress to gastric cancer. Possible modes of H. pylori transmission generally described are through direct contact between family members and also through contaminated water and food. Because the high prevalence of infection occurs mainly in developing countries and because the test-and-treat strategy puts a huge economic burden on many of these countries, it is time to take an immediate action toward this bacterial infection and adopt a strategy to prevent it. To address this issue, an updated prevalence of infection, modes of transmission, economics of infection and preventative measures to block the infection process have been discussed.

Helicobacter pylori infection in developing countries: the burden for how long?

Background Since "Helicobacter pylori (H. pylori) infection" was set as the indication in the Japanese Society for Helicobacter Research (JSHR) Guidelines 2009, eradication treatment for H. pylori gastritis is covered under insurance since 2013 in Japan, and the number of H. pylori eradication has rapidly increased. Under such circumstances, JSHR has made the third revision to the "Guidelines for diagnosis and treatment of H. pylori infection" for the first time in 7 years. Methods The Guideline Committee held 10 meetings. Articles published between the establishment of the 2009 Guidelines and March 2016 were reviewed and classified according to the evidence level; the statements were revised on the basis of this review. After inviting public comments, the revised statements were finalized using the Delphi method. Results There was no change in the basic policy that H. pylori infectious disease is an indication for eradication. Other diseases presumed to be associated with H. pylori infection were added as indications. Serum pepsinogen level, endoscopic examination, and X-ray examination were added to the diagnostic methods. The effects of 1-week triple therapy consisting of potassium-competitive acid blocker (P-CAB), amoxicillin, and clarithromycin have improved, and high eradication rates can also be expected with proton pump inhibitors (PPI) or P-CAB combined with amoxicillin and metronidazole. If the susceptibility test is not performed, the triple PPI or P-CAB/amoxicillin/metronidazole therapy should be chosen, because the PPI/amoxicillin/metronidazole combination demonstrated a significantly higher eradication rate than PPI/amoxicillin/clarithromycin. In the proposal for gastric cancer prevention, we divided gastric cancer prevention measures by age from adolescent to elderly, who are at an increased gastric cancer risk, and presented measures for gastric cancer prevention primarily based on H. pylori eradication. Conclusion We expect the revised guidelines to facilitate appropriate interventions for patients with H. pylori infection and accomplish its eradication and prevention of gastric cancer.

Guidelines for the management of Helicobacter pylori infection in Japan: 2016 Revised Edition.

Chronic abdominal pain is a common disorder in children and adolescents worldwide. It affects the child's wellbeing, and the costs from missed school days and use of healthcare resources are high. 

Children with chronic abdominal pain represent a heterogeneous population comprising both organic and functional gastrointestinal disorders. Functional disorders are those that cannot be explained by structural or biochemical abnormalities. Differences in prevalence of organic disease are reported depending on the setting, ranging from 5% in the general population to 40% in a paediatric gastroenterologist practice.1 General practitioners feel confident in labelling chronic abdominal pain as an easy to manage functional disorder. After minimal further testing, these children and their parents can be reassured by explaining that the symptoms are common and rarely associated with disease. However, when diagnostic uncertainty increases, pain does not resolve over time, or parents are hard to reassure, extensive testing and referral easily set in. As a consequence paediatricians perceive chronic abdominal pain as a time consuming and therapy resistant disorder.

#### SUMMARY POINTS

#### Sources and selection criteria

We used the Cochrane library to identify relevant systematic reviews that evaluated the effectiveness of pharmaceutical, psychological, and complementary interventions for chronic abdominal pain in children.

Medline searches were used to find relevant systematic reviews on diagnosis and treatment of abdominal pain in children using the keywords “abdominal …

/pdf/chronic-abdominal-pain-in-children-3dkoqbjmtt.pdf

Chronic abdominal pain in children.

https://www.gastrojournal.org/article/S0016-5085(05)02264-X/pdf

Age-specific incidence of Helicobacter pylori.

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Age-specific incidence of Helicobacter pylori.