Table 3.

Literature findings on the postoperative changes of gut microbiota

Ref.	Postoperative GM changes
	Increased abundance	Decreased abundance	Comments
Graessler et al[71], 2013	Enterobacter, Citrobacter, Neurospora, Veillonella, Salmonella, Shigella, E. coli tended to increase	Faecalibacterium, Coprococcus, Helicobacter, Dictyostelium, Epidinium, Anaerostipes, Nakamurella, Methanospirillum, Thermomicrobium	-
Kong et al[68], 2013	Bacteroides, Alistipes, Escherichia	Firmicutes (Lactobacillus, Dorea, Blautia) Bifidobacterium	Increased richness of GM after RYGB
Palleja et al[50], 2016	Escherichia coli, Klebsiella pneumoniae, 10 species belonging to the genus Streptococcus, 4 from Veillonella, 2 from Alistipes, Bifidobacterium dentium, Enterococcus faecalis, F. nucleatum, and Akkermansia muciniphila	E. prausnitzii	-
Tremaroli et al[64], 2015	Gammaproteobacteria; Several Proteobacteria (Escherichia, Klebsiella, Pseudomonas); E. coli tended to increase but was not statistically significant	3 species of Firmicutes; (Clostridium difficile, Clostridium hiranonis, Gemella sanguinis)	-

GM: Gut microbiota; RYGB: Roux-en-Y gastric bypass.