ABSTRACT
Members of the genus Klebsiella are widely distributed in nature and are ubiquitous in forest environments, soil, vegetation, and water. In the 1980s, these three genera were grouped together in the tribe Proteeae, based on similar phenotypic and morphologic features. In many ways these associations still remain valid. A number of biochemical features are almost exclusively associated with these three genera in the family Enterobacteriaceae and include production of phenylalanine deaminase, elaboration of a reddish-brown pigment on media containing DL-tryptophan, and the ability to degrade L-tryosine crystals via a tyrosine phenol-lyase. Members of the Proteeae are often isolated from homeothermic and poikilothermic species, including dogs, cows, birds, snakes, and fish. Some studies have found clonal relatedness between strains recovered from humans and their companion animals. Infection is often associated with close contact with reptiles. P. shigelloides, the only oxidase-positive member of the family, causes enteritis and is associated with consumption of seafood or shellfish or contaminated water.
