а) Urbanization – decrease in the diversity of the intestinal microbiota, the development of inflammatory bowel disease. Population decline of Prevotella, Bactiroides,
Xylanibacter and Firmicutes increase.
b) Caesarean section – the predominance of Staphylococcus species,
Corynebacterium and Propionibacterium (characteristic of the skin surface). In natural childbirth, bacteria of the Lactobacillus, Prevotella and Sneathia species are the predominant species.
c) Obesity (among women over 20 years old) – decrease in Bacteroides population, increase in Fermicutes. Reproduction of Archaea, provoking the breakdown of dietary fiber and the accumulation of acetate and butyrate.
d) Antibiotics – the development of resistance of pathogenic and opportunistic bacterial species, such as Staphylococcus aureus, Pseudomonas aeruginosa, Clostridium difficile, etc.
*data obtained using “rworldmap” package
**data for countries shown in white were not available
Source: USA, 2019