Microbiota in the stomach: New insights

Bacteria are sparsely distributed in the stomach due to the gastric microbicidal barrier. Several innate defenses (low pH, migrating motor complex and the entero-salivary circulation of nitrate) as well as external factors (diet, Helicobacter pylori infection, proton pump inhibitors, antibiotics and stomach diseases) have been shown to influence significantly the microbiota composition in the stomach. In recent years new culture-independent technologies have allowed the investigation of the cross talk that occurs between hosts and stomach-associated microflora, which helps us to understand the role of gastric bacterial flora in the gastrointestinal microbiological system, both in physiological and pathological conditions. Here, we reviewed the literatures related to this topic and set the stage for future developments of the field.