Status of Helicobacter pylori in Gut Microbiome and Precision Medicine

Helicobacter pylori (H. pylori) is a Gram-negative, slow-growing microaerobic bacterium that infects over 50% of the global population. Around 58,000 years ago, H. pylori and humans co-evolved and migrated from East Africa, the original birthplace of Homo sapiens. Its distinct characteristics, such as urease, helical structure, and motile flagella, allow it to survive in the human stomach under stressful conditions. The occurrence of H. pylori in the stomach can be beneficial or detrimental to human health, depending on the host's genetic vulnerability, immunity, and environmental factors. Although most of the H. pylori-infected patients are asymptomatic, about 20% develop stomach illnesses such as peptic ulcer (10-15%), gastric adenocarcinoma (1-3%), and mucosa-associated lymphoid tissue (MALT) lymphoma that is common to aged people. People who do not have H. pylori infection, on the other hand, are predisposed to a variety of diseases, including gastric esophageal disease (GERD), oesophageal cancer, diabetes mellitus, and asthma. Clinical symptoms in infected patients vary significantly geographically due to the high level of genetic variation in the bacterial genome and the presence of numerous virulence factors. The entire sickness is treated by eradicating H. pylori with antibiotics and proton pump inhibitors. However, the rise in antibiotic resistance and a lack of effective vaccinations make it tough to combat the infection. This chapter aims to shed light on host-pathogen interactions by analysing the bacterium's persistence and pathogenesis in the context of human health and precision medicine. 

Keywords: CagA, Gastric ulcer, Gastric cancer, Gut microbiota, Helicobacter pylori, Standard triple therapy, Virulence factors.