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Pronunciation: ak′ti-nō-mī-sē-tā′sē-ē

Definition: A family of nonsporeforming, nonmotile, ordinarily facultatively anaerobic (some species are aerobic and others are anaerobic) bacteria (order Actinomycetales) containing gram-positive, non-acid-fast, predominantly diphtheroid cells that tend to form branched filaments in tissue or in some stages of cultural development. The metabolism of these chemoheterotrophic bacteria is fermentative. This family contains the genera Actinomyces (type genus), Arachnia, Bacterionema, Bifidobacterium, and Rothia.

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