Gastric cancer remains a global killer with a shifting burden from the developed to the developing world. The cancer develops along a multistage process that is defined by distinct histological and pathophysiological phases. Several genetic and epigenetic alterations mediate the transition from one stage to another and these include mutations in oncogenes, tumour suppressor genes and cell cycle and mismatch repair genes. The most significant advance in the fight against gastric cancer came with the recognition of the role of Helicobacter pylori (H pylori) as the most important acquired aetiological agent for this cancer. Recent work has focussed on elucidating the complex host/microbial interactions that underlie the neoplastic process. There is now considerable insight into the pathogenesis of this cancer and the prospect of preventing and eradicating the disease has become a reality. Perhaps more importantly, the study of H pylori-induced gastric carcinogenesis offers a paradigm for understanding more complex human cancers. In this review, we examine the molecular and cellular events that underlie H pylori-induced gastric cancer.

Roseburia intestinalisFive strains of butyrate-producing, anaerobic, Gram-positive bacteria were isolated from human faecal material. These strains were slightly curved rods that showed motility by means of multiple subterminal flagella. The DNA G M C content of the strains was 29-31 mol %. A detailed investigation of the phenotypic and phylogenetic characteristics of the strains revealed that they represent a novel species of anaerobic, low-GMC-content, butyrate-producing bacterium that shows net acetate utilization during growth on media containing carbohydrates and short-chain fatty acids. The 16S rRNA gene sequences of the five isolates were determined and they confirmed that these strains were closely related to each other. Phylogenetic analysis indicated that the most closely related species are Eubacterium rectale, Eubacterium oxidoreducens and Roseburia cecicola, members of cluster XIVa of the Clostridium subphylum of Gram-positive bacteria, although they share less than 95 % sequence identity with the novel strains. It is proposed that a novel species, Roseburia intestinalis sp. nov., be created, with strain L1-82 T ( l DSM 14610 T l NCIMB 13810 T ) as the type strain.

Background Helicobacter pylori is the most infamous constituent of the gastric microbiota and its presence is the strongest risk factor for gastric cancer and other gastroduodenal diseases. Although historically the healthy stomach was considered a sterile organ, we now know it is colonised with a complex microbiota. However, its role in health and disease is not well understood. Aim To systematically explore the literature on the gastric microbiota in health and disease as well as the gut microbiota after bariatric surgery. Methods A systematic search of online bibliographic databases MEDLINE/EMBASE was performed between 1966 and February 2019 with screening in accordance with Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines. Randomised controlled trials, cohort studies and observational studies were included if they reported next‐generation sequencing derived microbiota analysis on gastric aspirate/tissue or stool samples (bariatric surgical outcomes). Results Sixty‐five papers were eligible for inclusion. With the exception of H pylori‐induced conditions, overarching gastric microbiota signatures of health or disease could not be determined. Gastric carcinogenesis induces a progressively altered microbiota with an enrichment of oral and intestinal taxa as well as significant changes in host gastric mucin expression. Proton pump inhibitors usage increases gastric microbiota richness. Bariatric surgery is associated with an increase in potentially pathogenic proteobacterial species in patient stool samples. Conclusion While H pylori remains the single most important risk factor for gastric disease, its capacity to shape the collective gastric microbiota remains to be fully elucidated. Further studies are needed to explore the intricate host/microbial and microbial/microbial interplay.

Background Fecal microbiota transplantation is an emerging therapeutic option, particularly for the treatment of recurrent Clostridioides difficile infection. Stool banks that organise recruitment and screening of feces donors are being embedded within the regulatory frameworks described in the European Union Tissue and Cells Directive and the technical guide to the quality and safety of tissue and cells for human application, published by the European Council. Objective Several European and international consensus statements concerning fecal microbiota transplantation have been issued. While these documents provide overall guidance, we aim to provide a detailed description of all processes that relate to the collection, handling and clinical application of human donor stool in this document. Methods Collaborative subgroups of experts on stool banking drafted concepts for all domains pertaining to stool banking. During a working group meeting in the United European Gastroenterology Week 2019 in Barcelona, these concepts were discussed and finalised to be included in our overall guidance document about fecal microbiota transplantation. Results A guidance document for all domains pertaining to stool banking was created. This document includes standard operating manuals for several processes involved with stool banking, such as handling of donor material, storage and donor screening. Conclusion The implementation of fecal microbiota transplantation by stool banks in concordance with our guidance document will enable quality assurance and guarantee the availability of donor feces preparations for patients.