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, whereas the remainder of the cell is unstained. They are not acid fast, are nonmotile, and do not produce spores; acetic and lactic acids are produced from glucose. Pathogenicity for humans is rare, although Bifidobacterium has been found in the feces and alimentary tract of infants, older people, and animals. The type species is Bifidobacterium bifidum.
[L. bifidus, cleft in two parts, + bacterium]
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Examples: glitazone, GI cocktail, etc.