Bifidobacterium

A genus of anaerobic bacteria (family Actinomycetaceae) containing Gram-positive rods of highly variable appearance; freshly isolated strains characteristically show true and false branching, with bifurcated V and Y forms, uniform or branched, and club or spatulate forms. They frequently stain irregularly; two or more granules may stain with methylene blue, while the remainder of the cell is unstained. They are not acid fast, are nonmotile, and do not produce spores; acetic and lactic acid s are produced from glucose. Pathogenicity for humans is rare, although they have been found in the feces and alimentary tract of infants, older people, and animals. The type species is B. bifidum. [L. bifidus, cleft in two parts, + bacterium]

- B. bifidum type species of the genus B.; it is found in the feces and alimentary tract of breast- and bottle-fed infants and of older persons, rats, turkeys, and chickens; also found in the rumen of cattle; pathogenicity for humans and other animals is rare. Associated with a growth factor belonging to a group of N-containing polysaccharides with a high hexosamine content and known as bifidus factor.

- B. dentium a bacterial species recovered in association with dental caries and periodontal disease. It is also an opportunistic pathogen, recovered in mixed infections associated with abscess formation.

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Bi·fid·o·bac·te·ri·um (bi″fid-o-bak-tērґe-əm) [bifidus + bacterium] a genus of gram-positive, anaerobic bacteria of the family Bifidobacteriaceae, occurring as irregularly staining rods of bifurcated Y and V forms and club or spatulate shapes.