Table 1.

Characteristics of gastric dysbiosis in different gastroduodenal diseases

Samples and subjects	Characteristics of dysbiosis	References
5 Dyspepsia and 10 gastric cancer samples	Domination of different species of the genera Streptococcus, Lactobacillus, Veillonella, and Prevotella with low abundance of H. pylori among patients with gastric cancer.	[86]
5 Patients with nonatrophic gastritis, intestinal metaplasia, and intestinal-type gastric cancer	Bacterial diversity index ranged from 8 to 57, with a decrease from atrophic gastritis to intestinal metaplasia and gastric cancer. Significant decrease in bacterial diversity observed from gastric cancer compared with nonatrophic gastritis.	[87]
10 Patients with chronic gastritis, 11 patients with noncardia gastric cancer, and 10 patients with intestinal metaplasia	Increased relative abundance of Streptococcaceae family with lower relative abundance of Helicobacteraceae family among the gastric cancer group compared with the chronic gastritis and intestinal metaplasia groups.	[64]
212 Patients with chronic gastritis and 103 patients with gastric cancer enrolled with only 12 patients (6 cancer and 6 chronic gastritis) carried out for microbiome analysis	Five genera bacteria, including Lactobacillus, Escherichia Shigella, Nitrospirae, Burkholderia fungorum, and Lachnospiraceae, were enriched among patients with gastric cancer. The presence of H. pylori heavily changed the structure of the microbiota with a small influence on the relative proportion of other bacteria.	[88]
81 Patients with chronic gastritis and 54 patients with gastric cancer	In general, the gastric carcinoma microbiota was characterized as having reduced microbial diversity with a decreased abundance of Helicobacter and enrichment of other bacteria genera, mostly represented by intestinal commensal bacteria. Specifically, Citrobacter, Lactobacillus, Clostridium, and Rhodococcus were also significantly more abundant in gastric carcinoma. Helicobacter, Neisseria, Prevotella, and Streptococcus were most abundant in the microbiota of patients with chronic gastritis.	[29]
21 Patients with superficial gastritis, 23 patients with atrophic gastritis, 17 patients with intestinal metaplasia, and 20 patients with gastric cancer	In general, there was significant mucosa microbial dysbiosis in the intestinal metaplasia and gastric cancer cases compared with cases of superficial gastritis. Several species, including Peptostreptococcus stomatis, Streptococcus anginosus, Parvimonas micra, Slackia exigua, and Dialister pneumosintes, were centralites in the ecological network analysis.	[30]
110 H. pylori-negative individuals and 7 H. pylori–positive patients	Significantly lower diversity among H. pylori–positive patients. A high abundance of Paludibacter sp. and Dialister sp. was observed among individuals with gastric damage.	[27]
24 Controls negative for H. pylori and with nongastritis with 11 additional H. pylori-negative gastritis patients with 40 H. pylori–positive patients	Significantly increased abundance of Streptococcus sp. and Haemophilus parainfluenzae among H. pylori-negative gastritis patients, whereas Treponema sp. was uniquely found in H. pylori-negative gastritis patients based on occurrence.	[56]
120 Patients without cancer (20 normal, 20 gastritis, 40 atrophic gastritis, and 40 intestinal metaplasia) and 48 patients with gastric cancer	The least diversity was seen among the gastritis and atrophic gastritis group. Lactobacilli and Enterococci were the dominant genus in several patients with cancer, especially in the absence of H pylori. In addition, Carnobacterium, Glutamicibacter, Paeniglutamicibacter, Fusobacterium, and Parvimonas were associated with gastric cancer regardless of H pylori infection.	[89]
230 Normal tissues, 247 peritumoral tissues, and 229 tumoral tissues from 276 patients with gastric cancer	The tumor microhabitat showed an increased abundance of Prevotella melaninogenica, Streptococcus anginosus, and Propionibacterium acne with decreased abundance of H. pylori, Prevotella copri, and Bacteroides uniformis.	[65]
288 Controls and 268 patients with gastric cancer	There is a different description of microbial community from different levels. At the species level, the patients with gastric cancer had higher relative abundances of H. pylori, Propionibacterium acnes, and Prevotella copri than the controls did, whereas the relative abundance of Lactococcus lactis was higher in the healthy controls than in the patients.	[71]
36 Paired nontumor tissue and gastric cardia adenocarcinoma samples	Increased relative abundance of Prevotella, Streptococcus, Veillonella, Haemophilus, and Neisseria among carcinoma tissue compared with nontumor tissue specimens.	[70]