Enterobacteriaceae

Members of the family are typically non-spore-forming, straight rods. They are generally facultative anaerobes that ferment glucose, and most reduce nitrate to nitrite and lack cytochrome c oxidase. Motility varies; motile members usually have peritrichous flagella, whereas other members are nonmotile.

The outer membrane contains lipopolysaccharide (LPS). Its lipid A component acts as an endotoxin and can provoke a strong inflammatory response; systemic exposure can contribute to septic shock.

Members of Enterobacteriaceae occupy diverse ecological niches. Some form part of the normal gut microbiota of humans and other animals, while others occur in freshwater, wastewater, soil, plants, or in association with insects.

Escherichia coli is an extensively studied model organism in genetics, biochemistry, and molecular biology. Pathogenic members of the family can cause intestinal or extraintestinal disease, including gastroenteritis, urinary tract infection, pneumonia, bloodstream infection, and meningitis.

The family name Enterobacteriaceae was conserved by Judicial Opinion 15, with Escherichia designated as its type genus, even though the family name is not formed from the name of that genus.

Enterobacteriaceae was formerly used for a much broader assemblage of bacteria. A genome-based revision established the order Enterobacterales and emended Enterobacteriaceae, while placing many former members in the families Budviciaceae, Erwiniaceae, Hafniaceae, Morganellaceae, Pectobacteriaceae, and Yersiniaceae.

A later comparative genomic analysis divided the family informally into six principal groups named for Escherichia, Klebsiella, Enterobacter, Kosakonia, Cronobacter, and Cedecea, together with an incertae sedis group. These groups were not established as formal subfamilies.

The 2016 genome-based analysis also reported 21 conserved signature indels distributed among 19 proteins in the Enterobacteriaceae taxa examined. These markers, together with phylogenomic analyses, were used to distinguish the family from other lineages within Enterobacterales.

The genus-level tree below is based on the GTDB R11-RS232 bacterial reference tree, with genus names following LPSN nomenclature. GTDB includes Shigella within Escherichia; Saccharobacter and Tenebrionicola are omitted because no representatives of their type species were found in this release.

The List of Prokaryotic names with Standing in Nomenclature recognizes the following 41 genera with validly published and correct names in Enterobacteriaceae. Synonyms and names without standing in nomenclature are excluded.

• Apirhabdus
• Buttiauxella
• Cedecea
• Citrobacter
• Cronobacter
• Dryocola
• Edaphovirga
• Enterobacillus
• Enterobacter
• Escherichia
• Franconibacter
• Gibbsiella
• Huaxiibacter
• Intestinirhabdus
• Izhakiella
• Jejuibacter
• Klebsiella
• Kluyvera
• Kosakonia
• Leclercia
• Lelliottia
• Limnobaculum
• Mangrovibacter
• Phytobacter
• Plesiomonas
• Pluralibacter
• Pseudescherichia
• Pseudocitrobacter
• Rosenbergiella
• Saccharobacter
• Salmonella
• Scandinavium
• Shigella
• Shimwellia
• Siccibacter
• Silvania
• Superficieibacter
• Tenebrionibacter
• Tenebrionicola
• Trabulsiella
• Yokenella

Some members of the family, particularly strains of E. coli and Klebsiella pneumoniae, have acquired resistance to carbapenem antibiotics. These organisms are included within the broader public-health category of carbapenem-resistant Enterobacterales (CRE), which is defined at the order level rather than being restricted to Enterobacteriaceae. CRE infections can be difficult to treat because the organisms may also be resistant to other classes of antibiotics.