Enterobacter is a genus of common Gram-negative, facultatively-anaerobic, rod-shaped bacteria of the family Enterobacteriaceae. Several strains of the these bacteria are pathogenic and cause opportunistic infections in immunocompromised (usually hospitalized) hosts. The urinary and respiratory tract are the most common sites of infection. Enterobacter can be distinguished from other GNR by virtue of being a 'fast fermenter' of lactose (as are E. coli and Klebsiella). Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... A facultative anaerobic organism is an organism, usually a bacterium, that makes ATP by aerobic respiration if oxygen is present but is also capable of switching to fermentation under anaerobic conditions. ... Species Bacillus anthracis Bacillus cereus Bacillus coagulans Bacillus natto Bacillus subtilis Bacillus thuringiensis etc. ... Subgroups Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular: bacterium) is everything in the kingdom Monera make up the majority of all living organisms. ... Genera see text The Enterobacteriaceae are a large family of bacteria, including many of the more familiar pathogens, such as Salmonella and Escherichia coli. ... A pathogen or infectious agent is a biological agent that causes disease or illness to its host. ... Opportunistic infections are infections caused by organisms and usually do not cause disease in a person with a healthy immune system, but can affect people with a poorly functioning or suppressed immune system. ... Immunosuppression is the medical suppression of the immune system. ... The urinary system is a system of organs, tubes, muscles, and nerves that work together to create, store, and carry, urine. ... In humans the respiratory tract is the part of the anatomy that has to do with the process of respiration or breathing. ...

Two clinically-important species from this genus are E. aerogenes and E. cloacae.