Table 1: Factors and medical conditions associated with changes in the composition of the faecal microbiota.

Factor/diseaseEffect/observationReferences

Caesarean sectionHigher numbers of the Clostridium difficile group l
Delayed/reduced colonisation with Bifidobacterium sp., Lactobacillus sp. and Bacteroides sp.
[1416]

Infant feedingFormula-fed infants with lower levels and diversity in Bifidobacterium sp. [11, 15, 17]

AgeingIncrease in Enterobacteriaceae and Bacteroidetes
Reduced levels of Bifidobacterium sp.
[18, 19]

Antibiotic-associated diarrhea and chronic C. difficile infectionsReduced diversity
Increase in Enterobacteriaceae and Firmicutes
Reduced levels of Bifidobacterium sp. and Bacteroidetes
[18, 2022]

Irritable bowel syndromeIncrease in Firmicutes
Reduced levels of Bacteroidetes and Bifidobacterium sp.
[2325]

Inflammatory bowel diseaseReduced diversity
Lower levels of Faecalibacterium sp.
Increase in Enterobacteriaceae and Bifidobacterium sp.
Reduced levels of Bifidobacterium sp. in pediatric IBD
[2629]

Atopic disease/AllergyIncrease in Clostridium sp.
Reduced levels of Bifidobacterium sp.
[3032]

AutismIncrease in Clostridium sp.
Reduced levels of Bifidobacterium sp.
[3335]