Table 1.

The effect of parenteral nutrition on gut microbiome composition.

Model	Bowel Resection	TPN Duration	Enteral Feeding		References
Rat-adult	No	14 days	No	Firmicutes/Bacteroidetes ratio; shift in favour of Bacteroidetes	[10]
Mouse-adult	No	5 days	No	Shift from Firmicutes to Proteobactoria and Bacteroidetes, i.e., Salmonella, Proteus, Escherichia, Bacteroides	[11]
Mouse-adult	No	5 days	No	Shift from Firmicutes to Bacteroidetes and Proteobacteria	[12]
Piglet-newborn	Yes	6 weeks	No	Changes in the composition of the Firmicutes phylum (decrease of Anaerotruncus, Clostridium, Ruminococcus, Peptostreptococcus; increase in Acidaminococcus and Mitsuokella)	[13]
Piglet-newborn	No	7 days	No	Lower total bacterial counts and reduced bacterial diversity, enriched in Clostridium difficile	[14]
Piglet-newborn	No	7 days	No	Enriched in C. perfringens and sulphated monosaccharide-degrading bacteria	[15]
Piglet-newborn	No	14 days	No	PN + ω-3: increased Parabacteroides	[16]
				PN + ω-6: increased Enterobacteriaceae
Human-pre-term newborn	Yes	Long-term	Yes	Higher diversity, higher abundance of Gram-negative bacteria, lower odds of death and late-onset sepsis cases	[17]
			No	Less diversity, lower abundance of Gram-negative bacteria, increased odds of death and late-onset sepsis cases
Human-paediatric/adult	Yes	Long-term	Yes	Increased Staphylococcus, Pseudomonas, Campylobacter, Propionibacterium, Chryseomonas	[18]
			No	Increased Enterobacter, Shigella, Klebsiella, Fusobacterium
Human-adult	Yes	Long-term	Yes	Enrichment in Lactobacillus/Leuconostoc; depletion of anaerobes, especially Clostridiaceae	[19,20]
Human-adult	Yes	Long-term	Yes	High abundance of Proteobacteria, especially Enterobacteriaceae and Fusobacteria; changes in the Firmicutes spectrum, depletion of Lachnospiraceae and Ruminococcaceae	[21]