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Not to be confused with Enteric bacteria.
Enterobacteriaceae
Citrobacter freundii.jpg
Citrobacter freundii, one member of the family
Scientific classification
Domain: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Enterobacteriales
Family: Enterobacteriaceae
Rahn, 1937

The Enterobacteriaceae are a large family of Gram-negative bacteria that includes, along with many harmless symbionts, many of the more familiar pathogens, such as Salmonella, Escherichia coli, Yersinia pestis, Klebsiella and Shigella. Other disease-causing bacteria in this family include Proteus, Enterobacter, Serratia, and Citrobacter. This family is the only representative in the order Enterobacteriales of the class Gammaproteobacteria in the phylum Proteobacteria.[1] Phylogenetically, in the Enterobacteriales, several peptidoglycan-less insect endosymbionts[citation needed] form a sister clade to the Enterobacteriaceae, but as they are not validly described, this group is not officially a taxon; examples of these species are Sodalis, Buchnera, Wigglesworthia, Baumannia cicadellinicola and Blochmannia, but not former Rickettsias.[2] Members of the Enterobacteriaceae can be trivially referred to as enterobacteria or "enteric bacteria",[3] as several members live in the intestines of animals. In fact, the etymology of the family is enterobacterium with the suffix to designate a family (aceae) — not after the genus Enterobacter (which would be "Enterobacteraceae")— and the type genus is Escherichia.

Characteristics[edit]

Members of the Enterobacteriaceae are rod-shaped, and are typically 1-5 μm in length. They appear as small grey colonies on blood agar. Like other proteobacteria, enterobacteria have Gram-negative stains,[4] and they are facultative anaerobes, fermenting sugars to produce lactic acid and various other end products. Most also reduce nitrate to nitrite, although exceptions exist (e.g. Photorhabdus). Unlike most similar bacteria, enterobacteria 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 nonmotile. They are not 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 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. Some enterobacteria produce endotoxins. Endotoxins reside in the cell cytoplasm and are released when the cell dies and the cell wall disintegrates. Some members of the Enterobacteriaeceae produce endotoxins that, when released into the bloodstream following cell lysis, cause a systemic inflammatory and vasodilatory response. The most severe form of this is known as endotoxic shock, which can be rapidly fatal.

Identification[edit]

To identify different genera of Enterobacteriaceae, a microbiologist may run a series of tests in the lab. These include:[5]

  • Phenol red
  • Tryptone broth
  • Phenylalanine agar for detection of production of deaminase, which converts phenylalanine to phenylpyruvic acid
  • Methyl red or Voges-Proskauer tests depend on the digestion of glucose. The methyl red tests for acid endproducts. The Voges Proskauer tests for the production of acetylmethylcarbinol.
  • Catalase test on nutrient agar tests for the production of catalase enzyme, which splits hydrogen peroxide and releases oxygen gas.
  • Oxidase test on nutrient agar tests for the production of the enzyme oxidase, which reacts with an aromatic amine to produce a purple color.
  • Nutrient gelatin tests to detect activity of the enzyme gelatinase.

In a clinical setting, three species make up 80 to 95% of all isolates identified. These are Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis.

Antibiotic resistance[edit]

Several Enterobacteriacea strains have been isolated which are resistant to antibiotics including carbapenem, which are often claimed as "the last line of antibiotic defense" against resistant organisms. For instance, some Klebsiella pneumonia strains are carbapenem resistant.[6]

Examples/classification[edit]

The following inexhaustive list details bacterial genera classified as members of Enterobacteriaceae.

Genera[edit]

References[edit]

  1. ^ Don J. Brenner, Noel R. Krieg, James T. Staley (July 26, 2005) [1984 (Williams & Wilkins)]. George M. Garrity, ed. The Gammaproteobacteria. Bergey's Manual of Systematic Bacteriology 2B (2nd ed.). New York: Springer. p. 1108. ISBN 978-0-387-24144-9. British Library no. GBA561951. 
  2. ^ Williams, K. P.; Gillespie, J. J.; Sobral, B. W. S.; Nordberg, E. K.; Snyder, E. E.; Shallom, J. M.; Dickerman, A. W. (2010). "Phylogeny of Gammaproteobacteria". Journal of Bacteriology 192 (9): 2305–2314. doi:10.1128/JB.01480-09. PMC 2863478. PMID 20207755.  edit
  3. ^ http://inst.bact.wisc.edu/inst/index.php?module=book&type=user&func=displayarticle&art_id=268
  4. ^ "Dorlands Medical Dictionary:Enterobacteriaceae". 
  5. ^ MacFaddin, Jean F. Biochemical Tests for Identification of Medical Bacteria. Williams & Wilkins, 1980, p 441.
  6. ^ Centers for Disease Control and Prevention - Klebsiella Quotation: "Increasingly, Klebsiella bacteria have developed antimicrobial resistance, most recently to the class of antibiotics known as carbapenems."

External links[edit]

  • Enterobacteriaceae genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
  • Evaluation of new computer-enhanced identification program for microorganisms: adaptation of BioBASE for identification of members of the family Enterobacteriaceae [1]
  • Brown, A.E. (2009). Benson's microbiological applications: laboratory manual in general microbiology. New York: McGraw- Hill.

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Enterobacteriaceae — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

128 news items

 
Hospital Healthcare Europe
Thu, 23 Oct 2014 03:18:45 -0700

The MicroSnap product range is simple rapid test for bacteria giving results in the same shift, and the range is extended to include Enterobacteriaceae. The measurement of Enterobacteriaceae is a useful indicator of surface hygiene and product quality ...
 
Monthly Prescribing Reference
Thu, 09 Oct 2014 11:45:00 -0700

PHILADELPHIA, PA—Ceftazidime-avibactam demonstrated “potent activity” against contemporary Enterobacteriaceae (ENT) strains, including those producing prevalent CTX-M-variants, a presentation at IDWeek 2014 concluded. This included E. coli, ...
 
Monthly Prescribing Reference
Fri, 10 Oct 2014 12:01:01 -0700

A total of 289 cases of Enterobacteriaceae gram-negative rod bacteremia were attributable to Klebsiella spp. (27%, of which 14% were MDR), E. coli (25%, of which 15% were MDR), Enterobacter (18%, of which 25% were MDR), and Salmonella, Citrobacter ...

Bioscience Technology

Bioscience Technology
Thu, 23 Oct 2014 09:18:45 -0700

The new technique, the researchers say, is superior to current imaging tools because it selectively precision-targets a common class of Gram-negative bacteria known as Enterobacteriaceae that includes notoriously virulent germs such as E. coli ...
 
Monthly Prescribing Reference
Thu, 09 Oct 2014 14:11:15 -0700

PHILADELPHIA, PA—Ceftolozane/tazobactam provides an empiric treatment option for infections caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, according to data presented at IDWeek 2014. Results of a pooled analysis of ...
 
GenomeWeb
Fri, 24 Oct 2014 09:07:30 -0700

Hunkapiller cited a National Institutes of Health study led by Julie Segre, which used the PacBio RS II system to retrospectively analyze a 2011 outbreak of antibiotic resistant Enterobacteriaceae at an NIH hospital as being key to driving attention to ...
 
Healio
Tue, 21 Oct 2014 03:18:45 -0700

Microbiological eradication was achieved in 81% of patients receiving ceftolozane/tazobactam vs. 61% of patients assigned a comparator. At a breakpoint of 8 mg/L, 90% of ESBL-producing Enterobacteriaceae were susceptible to ceftolozane/tazobactam.
 
Medscape
Mon, 20 Oct 2014 14:11:15 -0700

The treatment is increasingly being used to manage recurrent or refractory Clostridium difficile infections, but this is the first instance of its use to decolonize carbapenem-resistant enterobacteriaceae and return normal flora to the gut, the ...
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