pl. bifidobacteria [bifid + bacterium]
A genus of gram-positive, nonmotile anaerobic bacteria that live in the intestines and vagina. Two species are used clinically as probiotics. Bifidobacterium and Lactobacillus species (such as B. longum, B. infantis, and L. acidophilus) are used clinically as probiotic bacteria, i.e., they contribute to human health. They have been used to treat antibiotic-associated diarrhea, irritable bowel syndrome, and inflammatory bowel diseases and are also used in dairies to produce fermented milks and yogurt. The use of antibiotics to treat infectious diseases may decrease the concentration of Bifidobacterium in the gastrointestinal tract, allowing disease-causing bacteria to multiply.