Alteration of the esophageal microbiota in Barrett's esophagus and esophageal adenocarcinoma

Table 1 Esophageal microbiota studies on Barrett's esophagus and esophageal adenocarcinoma

Publication year	Sample population	Sequencing approach	Related notable findings	Ref
2004	Four patients with normal esophagus	16S rDNA	1 Members of six phyla, Firmicutes, Bacteroides, Actinobacteria, Proteobacteria, Fusobacteria, and TM7, were represented.	[32]
			2 Streptococcus (39%), Prevotella (17%), and Veilonella (14%) were most prevalent.
2007	Seven subjects without BE and seven patients with BE	16S rRNA	Campylobacter colonized the esophagus in the majority of BE patients and could not be identified in the control group.	[35]
2009	Thirty-four patients with normal, esophagitis, or Barrett's esophagus	16S rRNA	1 Esophageal microbiomes can be classified into two types.	[33]
			2 The type I microbiome was mainly composed of gram-positive bacteria, dominated by the genus Streptococcus and concentrated in the phenotypically normal esophagus.
			3 The type II microbiome contained a greater proportion of gram-negative anaerobes/microaerophiles and primarily correlated with esophagitis (Odds Ratio: 15.4) and BE (Odds Ratio: 16.5).
2012	Fifteen subjects	16S rRNA	The compositions of the esophageal microbiota were similar between the traditional biopsy and the overnight esophageal string test.	[52]
2014	Thirteen patients with esophagitis, six patients with BE, fifteen normal controls	16S rRNA	The Enterobacteriaceae family (mainly the genus Escherichia) is associated with esophageal abnormalities, such as esophagitis and BE.	[36]
2015	Twelve participants enrolled in the Seattle Barrett's Esophagus Research Program	16S rRNA	1 Streptococcus and Prevotella species dominate the upper GI and the ratio of these two species is associated with waist-to-hip ratio and hiatal hernia length, two known EAC risk factors in Barrett’s esophagus.	[27]
			2 Mucosal brush samples enhanced the detection of bacterial diversity in the esophagus and stomach, and the microbiota compositions were similar after replicate sampling.
2017	Twenty normal controls, twenty-four non- dysplastic BE twenty-three dysplastic BE	16S rRNA	1 The microbial diversity in the esophagus is decreased in EAC patients, regardless of the exact sampling locations.	[12]
			2 Lactobacillus fermentum was enriched in EAC patients, and lactic acid bacteria dominated and affected the microenvironment.
2018	Twenty-seven dental and esophageal disease-free individuals	16S rRNA	1 The phyla Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria, and TM7 were most abundant in both the oral cavity and the esophagus.	[28]
			2 The genera Streptococcus, Neisseria, Prevotella, Actinobacillus, and Veillonella were most abundant in both oral cavity and esophagus, and Streptococcus in the esophagus.
			3 No site-specific bacteria were found for three different segments (upper, middle, and lower) of the esophagus.

These studies displayed are sorted by the publication year. BE: Barrett’s esophagus; EAC: Esophageal adenocarcinoma; GI: Gastrointestinal.