A species of aerobic, Gram-positive, rod shaped bacteria assigned to the phylum Actinobacteria. This species is nonmotile, non-spore forming, catalase positive, oxidase negative, does not reduce nitrate, but does hydrolyze gelatin and casein. B. casei has a distinctive cheese smell, is commonly found in milk products and on human skin, but is pathogenic and known to be associated with sepsis, meningitis, and peritonitis.

Any bacterial organism that can be assigned to the species Brevibacterium casei.