Enterobacter

Abstract

The Enterobacter genus represents a large and heterogeneous group within the Enterobacteriaceae family. They are gram-negative, generally motile, oxidase-negative, nonspore forming, flagellated, rod-shaped, facultative anaerobes and they reduce nitrate. While over the years a total of 22 Enterobacter species have been proposed, taxonomic studies have led to the transfer of three Enterobacter species to alternative genera (E. intermedius = Kluyvera intermedia, E. agglomerans = Pantoea agglomerans, E. sakazakii = Cronobacter spp.). In addition, E. taylorae has been recognized as a heterotypic synonym of E. cancerogenus, and E. dissolvens has been reassigned as E. cloacae subspecies dissolvens comb. nov. Thus, the genus Enterobacter currently contains 17 distinct species. E. dissolvens, E. asburiae, E. hormaechei, E. kobei, E. ludwigii, and E. nimipressuralis are closely related to E. cloacae, having a DNA relatedness of over 60% and/or differing by one biochemical trait, and have been subsumed in the so-called E. cloacae-complex. Along with E. aerogenes, these are considered the main species that are frequently isolated from clinical samples. Only one species- Enterobacter sakazakii-is recognized as a foodborne pathogen, particularly in relation to infections in infants after ingestion of reconstituted powdered nutritional products.