In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall.
Enterobacterales with its type genus Enterobacter is an order of Gram-negative bacteria.
Escherichia is a genus of Gram-negative, non-spore-forming, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae. In those species which are inhabitants of the gastrointestinal tracts of warm-blooded animals, Escherichia species provide a portion of the microbially derived vitamin K for their host. A number of the species of Escherichia are pathogenic. The genus is named after Theodor Escherich, the discoverer of Escherichia coli. Escherichia are facultative aerobes, with both aerobic and anaerobic growth, and an optimum temperature of 37 °C. Escherichia are usually motile by flagella, produce gas from fermentable carbohydrates, and do not decarboxylate lysine or hydrolyze arginine. Species include E. albertii, E. fergusonii, E. hermannii, E. senegalensis, E. marmotae and most notably, the model organism and clinically relevant E. coli. Shimwellia blattae was formerly classified in this genus.
Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. It is the type genus of the order Enterobacterales. Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised hosts and in those who are on mechanical ventilation. The urinary and respiratory tracts are the most common sites of infection. The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms group of bacteria, unlike Escherichia coli, because it is incapable of growth at 44.5 °C in the presence of bile salts. Some of them show quorum sensing properties.
Providencia is genus of Gram-negative, motile bacteria of the family Morganellaceae. It was named after Providence, Rhode Island, where C. A. Stuart and colleagues studied these bacteria at Brown University.
Enterobacter cloacae is a clinically significant Gram-negative, facultatively-anaerobic, rod-shaped bacterium.
Pantoea is a genus of Gram-negative bacteria of the family Erwiniaceae, recently separated from the genus Enterobacter. This genus includes at least 20 species. Pantoea bacteria are yellow pigmented, ferment lactose, are motile, and form mucoid colonies. Some species show quorum sensing ability that could drive different gene expression, hence controlling certain physiological activities.
Cronobacter sakazakii, which before 2007 was named Enterobacter sakazakii, is an opportunistic Gram-negative, rod-shaped, pathogenic bacterium that can live in very dry places. The majority of Cronobacter sakazakii cases are adults but low-birth-weight preterm neonatal and older infants are highest at risk. The disease is associated with a rare cause of invasive infection infants with historically high case fatality rates (40–80%).
Cronobacter is a genus of Gram-negative, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped bacteria of the family Enterobacteriaceae. They are generally motile, reduce nitrate, use citrate, hydrolyze esculin and arginine, and are positive for L-ornithine decarboxylation. Acid is produced from D-glucose, D-sucrose, D-raffinose, D-melibiose, D-cellobiose, D-mannitol, D-mannose, L-rhamnose, L-arabinose, D-trehalose, galacturonate and D-maltose. Cronobacter spp. are also generally positive for acetoin production and negative for the methyl red test, indicating 2,3-butanediol rather than mixed acid fermentation. The type species of the genus Cronobacter is Cronobacter sakazakii comb. nov.
The Chloroflexi or Chlorobacteria are a phylum of bacteria containing isolates with a diversity of phenotypes, including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures; anoxygenic phototrophs, which use light for photosynthesis ; and anaerobic halorespirers, which uses halogenated organics as electron acceptors.
The genus Raoultella is composed of Gram-negative, oxidase-negative, aerobic, nonmotile, capsulated, facultatively anaerobic rods in the family Enterobacteriaceae. It is named after the French bacteriologist Didier Raoult.
Yokenella is a genus of bacteria of the family Enterobacteriaceae. Yokenella are Gram-negative, motile, rod-shaped bacteria. Strains of bacteria forming this genus were originally isolated from clinical samples and from insects. There is only one species in this genus: Yokenella regensburgei.
Yersinia kristensenii is a species of bacteria. It is Gram-negative and its type strain is 105. It is potentially infectious to mice. It secretes a bacteriocin that targets related species.
Enterobacter cowanii is a Gram-negative, motile, facultatively-anaerobic, rod-shaped bacterium of the genus Enterobacter. The species is typically associated with natural environments and is found in soil, water, and sewage. E. cowanii is associated with plant pathogens that exhibit symptoms of severe defoliation and plant death. This species, originally referred to as NIH Group 42, was first proposed in 2000 as a potential member of the family Enterobacteriaceae. The name of this species honors S. T. Cowan, an English bacteriologist, for his significant contributions to the field of bacterial taxonomy.
Samsonia is a genus of Gram-negative bacteria in the family Yersiniaceae. Species within this genus were originally found in the bark of diseased Erythrina trees. Among bacterial plant pathogens within the Enterobacterales, Samsonia species may be most closely related to Pectobacterium species. Until now, only one species of this genus has been described.
Escherichia hermannii is a Gram-negative, rod-shaped species of bacterium. Strains of this species were originally isolated from human wounds, sputum, and stool. The species is named for American microbiologists George J. Hermann and Lloyd G. Herman.
Shimwellia is a genus of Gram-negative bacteria of the family Enterobacteriaceae. The two species of Shimwellia are Shimwellia blattae and Shimwellia pseudoproteus.
Phytobacter is a genus of Gram-negative bacteria emerging from the grouping of isolates previously assigned to various genera of the family Enterobacteriaceae. This genus was first established on the basis of nitrogen fixing isolates from wild rice in China, but also includes a number of isolates obtained during a 2013 multi-state sepsis outbreak in Brazil and, retrospectively, several clinical strains isolated in the 1970s in the United States that are still available in culture collections, which originally were grouped into Brenner's biotype XII. Standard biochemical evaluation panels are lacking Phytobacter spp. from their database, thus often leading to misidentifications with other Enterobacterales species, especially Pantoea agglomerans. Clinical isolates of the species have been identified as an important source of extended-spectrum β-lactamase and carbapenem-resistance genes, which are usually mediated by genetic mobile elements. Strong protection of co-infecting sensitive bacteria has also been reported. Bacteria belonging to this genus are not pigmented, chemoorganotrophic and able to fix nitrogen. They are lactose fermenting, cytochrome-oxidase negative and catalase positive. Glucose is fermented with the production of gas. Colonies growing on MacConkey agar (MAC) are circular, convex and smooth with non-entire margins and an usually elevated center. Three species are currently validly included in the genus Phytobacter, which is still included within the Kosakonia clade in the lately reviewed family of Enterobacteriaceae. The incorporation of a fourth species, Phytobacter massiliensis, has recently been proposed via the unification of the genera Metakosakonia and Phytobacter.
The Morganellaceae are a family of Gram-negative bacteria that include some important human pathogens formerly classified as Enterobacteriaceae. This family is a member of the order Enterobacterales in the class Gammaproteobacteria of the phylum Proteobacteria. Genera in this family include the type genus Morganella, along with Arsenophonus, Cosenzaea, Moellerella, Photorhabdus, Proteus, Providencia and Xenorhabdus.
Yersinia rohdei is a Gram-negative species of Yersinia that was originally isolated from the feces of humans and dogs in addition to water surfaces. The type strain is ATCC 43380. Y. rohdei strains have also been isolated from reindeer and kelp gull from the sub-Antarctica South Georgia island.
