Enterobacteriaceae is a large family of Gram-negative bacteria. It was first proposed by Rahn in 1936, and now includes over 30 genera and more than 100 species. Its classification above the level of family is still a subject of debate, but one classification places it in the order Enterobacterales of the class Gammaproteobacteria in the phylum Pseudomonadota. In 2016, the description and members of this family were emended based on comparative genomic analyses by Adeolu et al.
Enterococcus is a large genus of lactic acid bacteria of the phylum Bacillota. Enterococci are gram-positive cocci that often occur in pairs (diplococci) or short chains, and are difficult to distinguish from streptococci on physical characteristics alone. Two species are common commensal organisms in the intestines of humans: E. faecalis (90–95%) and E. faecium (5–10%). Rare clusters of infections occur with other species, including E. casseliflavus, E. gallinarum, and E. raffinosus.
Serratia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria of the family Yersiniaceae. According to the List of Prokaryotic names with Standing Nomenclature (LPSN), there are currently 19 species of Serratia that are credibly published with accurate names as of 2020: S. aquatilis, S. entomophila, S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. marcescens, S. microhaemolytica, S. myotis, S. nematodiphila, S. odoriferae, S. oryzae, S. plymuthica, S. proteamaculans, S. quinivorans corrig, S. rubidaea, S. symbiotica, S. ureilytica, S. vespertilionis. They are typically 1–5 μm in length, do not produce spores, and can be found in water, soil, plants, and animals. Some members of this genus produce a characteristic red pigment, prodigiosin, and can be distinguished from other members of the order Enterobacterales by their unique production of three enzymes: DNase (nucA), lipase, and gelatinase (serralysin). Serratia was thought to be a harmless environmental bacteria until it was discovered that the most common species in the genus, S. marcescens, is an opportunistic pathogen of many animals, including humans. In humans, S. marcescens is mostly associated with nosocomial, or hospital-acquired, infections, but can also cause urinary tract infections, pneumonia, and endocarditis. S. marcescens is frequently found in showers, toilet bowls, and around wetted tiles as a pinkish to red biofilm but only causes disease in immunocompromised individuals. Aside from S marcescens, some rare strains of the Serratia species S. plymuthica, S. liquefaciens, S. rubidaea, and S. odoriferae have been shown to cause infection such as osteomyelitis and endocarditis.
Acinetobacter is a genus of gram-negative bacteria belonging to the wider class of Gammaproteobacteria. Acinetobacter species are oxidase-negative, exhibit twitching motility, and occur in pairs under magnification.
A hospital-acquired infection, also known as a nosocomial infection, is an infection that is acquired in a hospital or other health care facility. To emphasize both hospital and nonhospital settings, it is sometimes instead called a healthcare–associated infection. Such an infection can be acquired in hospital, nursing home, rehabilitation facility, outpatient clinic, diagnostic laboratory or other clinical settings. Infection is spread to the susceptible patient in the clinical setting by various means. Health care staff also spread infection, in addition to contaminated equipment, bed linens, or air droplets. The infection can originate from the outside environment, another infected patient, staff that may be infected, or in some cases, the source of the infection cannot be determined. In some cases the microorganism originates from the patient's own skin microbiota, becoming opportunistic after surgery or other procedures that compromise the protective skin barrier. Though the patient may have contracted the infection from their own skin, the infection is still considered nosocomial since it develops in the health care setting. An easy way to understand the term is that the infection tends to lack evidence that it was incubating, or present when the patient entered the healthcare setting, thus meaning it was acquired post-admission.
Enterobacterales is an order of Gram-negative, non-spore forming, facultatively anaerobic, rod-shaped bacteria with the class Gammaproteobacteria. The type genus of this order is Enterobacter.
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. marmotae and most notably, the model organism and clinically relevant E. coli. Shimwellia blattae was formerly classified in this genus.
Vancomycin-resistant Enterococcus, or vancomycin-resistant enterococci (VRE), are bacterial strains of the genus Enterococcus that are resistant to the antibiotic vancomycin.
Ralstonia is a genus of bacteria, previously included in the genus Pseudomonas. It is named after the American bacteriologist Ericka Ralston. Ericka Ralston was born Ericka Barrett in 1944 in Saratoga, California, and died in 2015 in Sebastopol, California. While in graduate school at the University of California at Berkeley, she identified 20 strains of Pseudomonas which formed a phenotypical homologous group, and named them Pseudomonas pickettii, after M.J. Pickett in the Department of Bacteriology at the University of California at Los Angeles, from whom she had received the strains. Later, P. pickettii was transferred to the new genus Ralstonia, along with several other species. She continued her research into bacterial pathogenesis under the name of Ericka Barrett while a professor of microbiology at the University of California at Davis from 1977 until her retirement in 1996.
Ralstonia pickettii is a Gram-negative, rod-shaped, soil bacterium.
Enterobacter cloacae is a clinically significant Gram-negative, facultatively-anaerobic, rod-shaped bacterium.
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, otherwise known as xerotolerance. C. sakazakii utilizes a number of genes to survive desiccation and this xerotolerance may be strain specific. The majority of C. sakazakii cases are adults but low-birth-weight preterm neonatal and older infants are at the highest risk. The pathogen is a rare cause of invasive infection in 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.
Cronobacter turicensis is a bacterium. It is usually food-borne and pathogenic. It is named after Turicum, the Latin name of Zurich, as the type strain originates from there. Its type strain is strain 3032. This strain was first isolated from a fatal case of neonatal meningitis. C. Turicensis strains are indole negative but malonate, dulcitol and methyl-α-D-glucopyranoside positive.
Cronobacter dublinensis is a bacterium. Its name pertains to Dublin, the origin of the type strain. The type strain is originally from a milk powder manufacturing facility. C. dublinensis sp. nov. is dulcitol negative and methyl-α-D-glucopyranoside positive and generally positive for indole production.
Cronobacter muytjensii is a bacterium. It is named after Harry Muytjens. Its type strain is ATCC 51329T. It is indole, dulcitol, and malonate positive but palatinose and methyl-α-D-glucopyranoside negative.
Cronobacter malonaticus, formerly considered a subspecies of Cronobacter sakazakii, is a bacterium. Its type strain is CDC 1058-77T.
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.
Pluralibacter is a genus of Gram negative bacteria from the family of Enterobacteriaceae. The genus consists of two species, P. gergoviae and P. pyrinus. Both species were originally classified in the genus Enterobacter, but were reclassified into the novel genus Pluralibacter in 2013.
Pluralibacter pyrinus is a Gram-negative, motile, facultatively-anaerobic, rod-shaped bacterium. P. pyrinus is the causitive agent of brown leaf spot disease of pear trees.
