Bacteria and other microorganisms that are normally present in the gastrointestinal tract.
Beneficial bacteria which are always present in the intestine.
Bacteria present in the intestines, necessary for digestion and metabolism of certain nutrients.
Microorganisms (e.g., Escherichia coli) normally present in the intestinal tract and essential to its normal function.
Bacteria normally present in the intestinal tract. Some are responsible for the synthesis of vitamin K. By producing a highly acidic environment in the intestine they may also prevent infection by pathogenic bacteria that cannot tolerate such conditions.
Bacteria present in the intestines. The colon of the fetus is sterile, but bacteria are acquired during vaginal birth and subsequently from people and the environment. These bacteria produce vitamins, especially vitamin K, and inhibit the growth of pathogens. Certain antibiotics may reduce the number and kinds of bacteria present.