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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.

2955 news items

 
Industry Today (press release)
Thu, 30 Oct 2014 03:30:00 -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 ...
 
wivb.com
Mon, 17 Nov 2014 14:40:09 -0800

CRE bacteria (enterobacteriaceae) which is up among people in hospitals. Almost half of those infected with the CRE bacteria die, the CDC said. And, the drug resistant Neisseria Gonorrhoeae, a sexually transmitted disease, is the second most commonly ...
 
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, ...
 
Nature.com
Thu, 13 Nov 2014 22:46:23 -0800

In support of an indirect effect of influenza virus on the intestines, Wang et al. showed that there was a decrease in the numbers of segmented filamentous bacteria, Lactobacilli and Lactococci, and an increase in the number of Enterobacteriaceae ...
 
ConsumerReports.org
Sat, 15 Nov 2014 03:07:10 -0800

... a germ that can no longer be easily controlled by antibiotics and was linked to 11,000 deaths in 2011. Other bacteria are becoming more common, too, including carbapenem-resistant Enterobacteriaceae. It recently increased fivefold in community ...
 
GenomeWeb
Wed, 17 Sep 2014 11:47:17 -0700

NEW YORK (GenomeWeb) – A new long-read sequencing study in Science Translational Medicine has started to untangle the complexity behind plasmid-mediated antibiotic resistance in hospital-acquired infections involving Enterobacteriaceae pathogens.
 
CNNMoney
Mon, 10 Nov 2014 04:00:00 -0800

Achaogen is developing plazomicin, Achaogen's lead product candidate, for the treatment of serious bacterial infections due to MDR Enterobacteriaceae, including CRE. Through the Special Protocol Assessment procedure, the FDA has agreed that the ...
 
Medscape
Thu, 13 Nov 2014 22:45:00 -0800

Two of those were pure cultures of Propionibacterium acnes; two were of corynebacteria, enterobacteriaceae, and coagulase-negative staphylococci; and one was a pure culture of Streptococcus pyogenes, probably associated with an unrelated acute ...
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