Table 6.

Diseases associated with gut microbiota abnormalities

Disease	Features
Irritable bowel syndrome	An abundance of Firmicutes and a decrease of Bacteroidetes
Type I diabetes	In genetically predisposed individuals, autoimmune against pancreatic β-cells. Deficient development or alteration of the microbiota may contribute to dysfunctional immunity with the devastation of autoimmune β-cells and increased leakiness of the intestinal barrier. Variability of microbiomes reduced
Asthma	Outbreaks of Chlamidophila pneumonia during bronchitis and pneumonia development affect the airway microbiome. Gut microbiota is influenced by the introduction of microbiota to the environment, particularly in early life, which helps immune function growth and the development of defending against allergic sensitization
Food-borne pathogens and food poisoning	Opportunistic pathogens (Campylobacter, Salmonella, Escherichia coli, Shigella) disturb the microbiome’s balance leading to dysbiosis
Malnutrition	Decrease or missing species that either process food categories efficiently or produce vitamins may reduce the absorption of nutrients. An overabundance of Enetrobacteriaceae can lead to epithelial damage, diarrhea, and limited absorption of nutrients
Depression	In physiologic system, Bifidobacterium infantis, generally found in infants’ gastrointestinal tract and administered probiotic drugs, can have antidepressant effects
Anxiety	Oral administration of Campylobacter jejuni subclinical doses in murine models induced anxiety like behavior without stimulating immunity