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The Enterobacteriaceae are a large family of , including many of the more familiar pathogens, such as Salmonella and Escherichia coli. Genetic studies place them among the Proteobacteria, and they are given their own order (Enterobacteriales), though this is sometimes taken to include some related environmental samples.


Members of the Enterobacteriaceae are rod-shaped, and are typically 1-5 Ám in length. Like other Proteobacteria they have Gram-negative stains,[1] and they are facultative anaerobes, fermenting sugars to produce lactic acid and various other end products. Most also reduce nitrate to nitrite, a lthough exceptions exist (e.g. Photorhabdus). Unlike most similar bacteria, Enterobacteriaceae generally lack cytochrome C oxidase, although there are exceptions (e.g. Plesiomonas shigelloides). Most have many flagella used to move about, but a few genera are non-motile. They are non-spore forming. Catalase reactions vary among Enterobacteriaceae.

Many members of this family are a normal part of the gut flora found in the intestines of humans and other animals, while others are found in water or soil, or are parasites on a variety of different animals and plants. Escherichia coli, better known as E. coli, is one of the most important model organisms, and its genetics and biochemistry have been closely studied.

Most members of Enterobacteriaceae have peritrichous Type I fimbriae involved in the adhesion of the bacterial cells to their hosts.




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The Family Enterobacteriaceae is further organized into finer groupings including:


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A genus in the Kingdom Bacteria. [more]






Citrobacter is a of Gram-negative coliform bacteria in the Enterobacteriaceae family. [more]



Enterobacter is a genus of common , 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. [more]


Erwinia is a genus of bacteria containing mostly plant pathogenic species which was named for the first phytobacteriologist, Erwin Smith. It is a gram negative bacterium related to E.coli, Shigella, Salmonella and Yersinia. It is primarily a rod-shaped bacteria. A well-known member of this genus is the species E. amylovora, which causes fireblight on apple, pear, and other Rosaceous crops. Erwinia carotovora (now known as Pectobacterium carotovorum)[citation needed] is another species, which causes diseases in many plants. These species produce enzymes that hydrolyze pectin between individual plant cells. This causes the cells to separate, a disease plant pathologists term plant rot. [more]


Escherichia is a of Gram-negative, non-spore forming, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae. Inhabitants of the gastrointestinal tracts of warm-blooded animals, Escherichia species provide a portion of the microbially-derived vitamin K for their host. [more]



A Genus in the Kingdom Bacteria. [more]










Pantoea is a genus of bacteria of the family Enterobacteriaceae. It comprises seven species and two sub-species. [more]








A Genus in the Kingdom Animalia. [more]






Salmonella is a of rod-shaped, Gram-negative, non-spore forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 Ám, lengths from 2 to 5 Ám, and flagella which project in all directions (i.e. peritrichous). They are chemoorganotrophs, obtaining their energy from oxidation and reduction reactions using organic sources and are facultative anaerobes; most species produce hydrogen sulfide, which can readily be detected by growing them on media containing ferrous sulfate, such as TSI. Most isolates exist in two phases; phase I is the motile phase and phase II the non-motile phase. Cultures that are non-motile upon primary culture may be swithched to the motile phase using a Craigie tube. [more]


Serratia is a of Gram-negative, facultatively anaerobic, rod-shaped bacteria of the Enterobacteriaceae family. The most common species in the genus, S. marcescens, is normally the only pathogen and usually causes nosocomial infections. However, rare strains of S. plymuthica, S. liquefaciens, S. rubidaea, and S. odoriferae have caused diseases through infection. Members of this genus produce characteristic red pigment, prodigiosin, and can be distinguished from other members of the family Enterobacteriaceae by its unique production of three enzymes: DNase, lipase, and gelatinase. [more]


Shigella is a of Gram-negative, non-spore forming rod-shaped bacteria closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella cause disease in primates, but not in other mammals. It is only naturally found in humans and apes. During infection, it typically causes dysentery. [more]










Yersinia is a of bacteria in the family Enterobacteriaceae. Yersinia are Gram-negative rod shaped bacteria, a few micrometers long and fractions of a micrometer in diameter, and are facultative anaerobes. Some members of Yersinia are pathogenic in humans; in particular, Y. pestis is the causative agent of the bubonic plague. Rodents are the natural reservoirs of Yersinia; less frequently other mammals serve as the host. Infection may occur either through blood (in the case of Y. pestis) or in an alimentary fashion, occasionally via consumption of food products (especially vegetables, milk-derived products and meat) contaminated with infected urine or feces. [more]

At least 16 species and subspecies belong to the Genus Yersinia.

More info about the Genus Yersinia may be found here.


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  1. ^ "Dorlands Medical Dictionary:Enterobacteriaceae".


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Last Revised: April 26, 2010
2010/04/26 14:38:13