title: The human gastric microbiota: Is it time to rethink the pathogenesis of stomach diseases?
abstract: BACKGROUND
  Although long thought to be a sterile organ, due to its acid production, the human stomach holds a core microbiome.
  
  
  OBJECTIVE
  To provide an update of findings related to gastric microbiota and its link with gastric diseases.
  
  
  METHODS
  We conducted a systematic review of the literature.
  
  
  RESULTS
  The development of culture-independent methods facilitated the identification of many bacteria. Five major phyla have been detected in the stomach: Firmicutes, Bacteroidites, Actinobacteria, Fusobacteria and Proteobacteria. At the genera level, the healthy human stomach is dominated by Prevotella, Streptococcus, Veillonella, Rothia and Haemophilus; however, the composition of the gastric microbiota is dynamic and affected by such factors as diet, drugs and diseases. The interaction between the pre-existing gastric microbiota and Helicobacter pylori infection might influence an individual's risk of gastric disease, including gastric cancer.
  
  
  CONCLUSIONS
  The maintenance of bacterial homeostasis could be essential for the stomach's health and highlights the chance for therapeutic interventions targeting the gastric microbiota, even if gastric pH, peristalsis and the mucus layer may prevent bacteria colonization; and the definition of gastric microbiota of the healthy stomach is still an ongoing challenging task.
authors.affiliation: Department of Clinical Medicine and Surgery, University Federico II, Naples, Italy.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Nardone
authors.affiliation: Department of Clinical Medicine and Surgery, University Federico II, Naples, Italy.
authors.forename: Debora
authors.initials: D
authors.lastname: Compare
keywords: Gastric cancer; Helicobacter pylori; gastric microbiota; gastritis; review; stomach bacteria; stomach cancer