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The present study explored the differences in gastric microbiome between three distinct populations of Southeast Asia. These include the isolated Orang Asli population and modern Malaysians, as well as patients from Myanmar, the least developed country in the region. All 79 subjects recruited in this study had Helicobacter pylori infection. Based on alpha diversity analysis, Orang Asli had the richest and most diverse gastric microbiome, followed by Myanmar and modern Malaysian groups. Beta diversity analysis revealed significant separation of samples between different populations. These observations are likely to be associated with the level of modernization of each population. Our data further suggested increased bacterial species richness and diversity of the gastric microbiome in individuals who were less modernized, particularly in the Orang Asli group, could suppress the growth of H. pylori. In addition, there were significant variations in the gastric microbiome between modern Malaysians with different types of gastric diseases. Notably, Cutibacterium acnes was present at significantly greater abundance level in patients with non-ulcerative dyspepsia than those with peptic-ulcer diagnosis. This suggests that C. acnes may also play a role in gastritis besides H. pylori, which merits further investigation.

Helicobacter pylori infection results in diverse clinical conditions ranging from chronic gastritis and ulceration to gastric adenocarcinoma. Among the multiethnic population of Malaysia, Indians consistently have a higher H. pylori prevalence as compared with Chinese and Malays. Despite the high prevalence of H. pylori, Indians have a relatively low incidence of peptic ulcer disease and gastric cancer. In contrast, gastric cancer and peptic ulcer disease incidence is high in Chinese. H. pylori strains from Chinese strains predominantly belong to the hspEAsia subpopulation while Indian/Malay strains mainly belong to the hspIndia subpopulation. By comparing the genome of 27 Asian strains from different subpopulations, we identified six genes associated with risk of H. pylori-induced peptic ulcer disease and gastric cancer. This study serves as an important foundation for future studies aiming to understand the role of bacterial factors in H. pylori-induced gastro-duodenal diseases.

Helicobacter pylori causes human gastroduodenal diseases, including chronic gastritis and peptic ulcer disease. It is also a major microbial risk factor for the development of gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Twenty-one strains with different ethnicity, disease, and antimicrobial susceptibility backgrounds were sequenced by use of Illumina HiSeq and PacBio RS platforms.

Helicobacter pylori is the main bacterial causative agent of gastroduodenal disorders and a risk factor for gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. The draft genomes of 10 closely related H. pylori isolates from the multiracial Malaysian population will provide an insight into the genetic diversity of isolates in Southeast Asia. These isolates were cultured from gastric biopsy samples from patients with functional dyspepsia and gastric cancer. The availability of this genomic information will provide an opportunity for examining the evolution and population structure of H. pylori isolates from Southeast Asia, where the East meets the West.