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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 Enterobacteriaceae 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 pneumoniae 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.
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2911 news items

Benzinga

Benzinga
Fri, 15 May 2015 02:56:15 -0700

With Smarticles™ technology, GeneWEAVE is developing fast, direct-from-patient-sample tests for critical MDROs such as MRSA, CRE, and FRE (Fluoroquinolone-Resistant Enterobacteriaceae) to allow healthcare providers to make time-critical decisions.
 
PR Newswire (press release)
Wed, 27 May 2015 05:56:15 -0700

SHARE ID will focus its initial efforts on the deadly Gram-negative infections identified by the Centers for Disease Control and Prevention (CDC) as urgent public health concerns. According to the CDC, carbapenem-resistant Enterobacteriaceae (CRE) is ...

International Business Times

International Business Times
Mon, 25 May 2015 11:56:15 -0700

The World Health Assembly endorsed a global action plan Monday to address climbing rates of antimicrobial resistance, including antibiotic resistance and the rise of superbugs such as the carbapenem-resistant enterobacteriaceae shown above.

Times of India

Times of India
Tue, 26 May 2015 12:07:30 -0700

Pseudomonas, streptococcus, micrococcus, staphylococcus, acinetobacter, neisseria, hemophilus genus members and enterobacteriaceae (E-coli K1 strain & K pneumoniae) family species. STEPS FOLLOWED IN CIIMS RESEARCH LAB TEST Taking out ...

Kansas City Star

Huffington Post
Thu, 19 Feb 2015 06:42:44 -0800

Seven patients are infected and almost 200 others were exposed to a potentially fatal group of "superbugs" carbapenem-resistant Enterobacteriaceae, or CRE, at Ronald Reagan UCLA Medical Center. The bug may have played a role in the deaths of two ...

Legal Examiner

Legal Examiner
Tue, 26 May 2015 05:22:30 -0700

In 2009, State and Federal health officials warned the Food and Drug Administration (FDA) to alert hospitals about the risks of contamination from specialized medical scopes. Such contamination is to blame for a recent series of deadly “superbug ...

Nursing Times

Nursing Times
Sun, 17 May 2015 22:48:45 -0700

Cases of carbapenemase-producing enterobacteriaceae (CPEs) are rising in the UK and around the world. Guidelines from Public Heath England outline methods for screening and managing CPEs, although the implementation is costly. Managing CPEs ...

Chicago Sun-Times

Chicago Sun-Times
Fri, 22 May 2015 20:14:02 -0700

... which are inserted through the throat to diagnose problems in the pancreas or bile ducts — to infections at the Park Ridge hospital and elsewhere of the CRE, or carbapenem-resistant enterobacteriaceae, a potentially deadly, antibiotic-resistant ...
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