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| {{Taxobox
| | #redirect [[Listeria monocytogenes]] |
| | color = lightgrey <!-- Please read [[WP:Taxobox_usage#Color]] before making any changes to the taxobox color. -->
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| | name = ''Listeria''
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| | image =
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| | image_width = 240px
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| | image_caption = [[Scanning electron microscope|Scanning electron micrograph]] of ''Listeria monocytogenes''.
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| | regnum = [[Bacterium|Bacteria]]
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| | divisio = [[Firmicutes]]
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| | classis = [[Bacilli]]
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| | ordo = [[Bacillales]]
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| | familia = [[Listeriaceae]]
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| | genus = ''[[Listeria]]''
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| | genus_authority = Pirie 1940
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| | subdivision_ranks = Species
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| | subdivision =
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| ''[[Listeria grayi|L. grayi]]''<br />
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| ''[[Listeria innocua|L. innocua]]''<br />
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| ''[[Listeria ivanovii|L. ivanovii]]''<br />
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| ''[[Listeria monocytogenes|L. monocytogenes]]''<br />
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| ''[[Listeria seeligeri|L. seeligeri]]''<br />
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| ''[[Listeria welshimeri|L. welshimeri]]''
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| }}
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| ==Overview==
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| '''''Listeria''''' is a [[bacteria|bacterial]] [[genus]] containing six species. Named in honour of [[Joseph Lister]], ''Listeria'' species are [[Gram positive]] [[bacilli]] and are typified by ''[[Listeria monocytogenes|L. monocytogenes]]'', the causative agent of [[Listeriosis]].
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| ''Listeria ivanovii'' is a pathogen of [[ruminant]]s, and can infect [[mouse|mice]] in the laboratory, although it is only rarely the cause of human [[disease]].
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| ==''Listeria monocytogenes''==
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| ''Listeria monocytogenes'' is a bacterium commonly found in soil, stream water, sewage, plants, and food.<ref name="rts1">{{cite web
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| | last =Southwick
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| | first =F.S.
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| | authorlink =
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| | coauthors =D.L Purich
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| | title =More About Listeria
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| | work =
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| | publisher =University of Florida Medical School
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| | date =
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| | url =http://www.med.ufl.edu/biochem/DLPURICH/morelist.html
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| | format =
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| | doi =.
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| | accessdate = 7 March 2007 }}</ref> Each bacterium is Gram-positive and rod-shaped. ''Listeria'' are known to be the bacteria responsible for [[listeriosis]], a rare but lethal food-borne infection that has a devastating mortality rate of 25%<ref name="rts2"> {{cite web
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| | last =
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| | first =
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| | authorlink =
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| | coauthors =
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| | title =Todar's Online Textbook of Bacteriology
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| | work =Listeria monocytogenes and Listeriosis
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| | publisher =Kenneth Todar University of Wisconsin-Madison Department of Biology
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| | date = 2003
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| | url =http://textbookofbacteriology.net/Listeria.html
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| | format =
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| | doi =.
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| | accessdate = 2007-03-07 }} </ref>([[Salmonella]], in comparison, has a less than 1% mortality rate<ref name="rts3">{{cite web
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| | last =
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| | first =
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| | authorlink =
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| | coauthors =
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| | title =Statistics about Salmonella food poisoning
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| | work =
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| | publisher =WrongDiagnosis.com
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| | date = 27 February 2007
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| | url =http://www.wrongdiagnosis.com/s/salmonella_food_poisoning/stats.htm
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| | format =
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| | doi =.
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| | accessdate = 2007-03-07 }}</ref>). They are incredibly hardy and able to grow in temperatures ranging from 4°C (39°F), the temperature of a refrigerator, to 37°C (99°F), the body's internal temperature<ref name="rts1"/>. Furthermore, listerosis's deadliness can be partially attributed to the infection's ability to spread to the nervous system and cause [[meningitis]].<ref name="rts1"/> Finally, ''Listeria'' has a particularly high occurrence rate in newborns because of its ability to infect the fetus by penetrating the endothelial layer of the [[placenta]].<ref name="rts2"/>
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| ==Pathogenesis==
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| ''Listeria'' uses the cellular machinery to move around inside the host cell: it induces directed polymerization of [[actin]] by the ActA [[transmembrane protein]], thus pushing the bacterial cell around.
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| ''Listeria'' ''monocytogenes'' for example, encodes virulence genes which are thermoregulated. The expression of virulence factor is optimal at 37 degrees Celsius and is controlled by a transcriptional activator, PrfA, whose expression is thermoregulated by the [[PrfA thermoregulator UTR]] element. At low temperatures, the PrfA transcript is not translated due to [[Cis-regulatory element|structural elements]] near the ribosome binding site. As the bacteria infects the host, the temperature of the host melts the structure and allows translation initiation for the virulent genes.
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| ==Mechanism of Infection==
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| The majority of ''Listeria'' bacteria are targeted by the [[immune system]] before they are able to cause [[infection]]. Those that escape the immune system's initial response, however, spread though intracellular mechanisms and are therefore guarded against circulating immune factors (AMI).<ref name="rts2"/>
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| To invade, ''Listeria'' induces macrophage [[phagocytosis|phagocytic]] uptake by displaying D-galactose receptors that are then bound by the [[macrophage]]'s [[polysaccharide]] receptors (Notably, in most bacterial infections it is the host cell, not the bacteria, that displays the polysaccharide). <ref name="rts3"/> Once phagocytosed, the bacteria is encapsulated by the host cell's acidic phagolysosome organelle. <ref name="rts1"/> ''Listeria'', however, escapes the phagolysosome by lysing the vacuole's entire membrane with secreted hemolysin, <ref name="rtsjournal1">{{cite journal | quotes=no |author= Tinley, L.G. et al |year=1989|url=http://www.jcb.org/cgi/reprint/109/4/1597|title= Actin Filaments and the Growth, Movement, and Spread of the Intracellular Bacterial Parasite, ''Listeria monocytogenes'' |journal=The Journal of Cell Biology |volume=109 |pages=1597-1608}}</ref> now characterized as the exotoxin [[listeriolysin O]].<ref name="rts1"/> The bacteria then replicate inside the host cell's cytoplasm. <ref name="rts2"/>
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| ''Listeria'' must then navigate to the cell's periphery to spread the infection to other cells. Outside of the body, ''Listeria'' has [[flagella]]r-driven motility. However, at 37°C, flagella cease to develop and the bacteria instead usurps the host cell's [[cytoskeleton]] to move. <ref name="rts2"/> ''Listeria'', inventively, polymerizes an [[actin]] tail or "comet" <ref name="rtsjournal1"/>, using host-produced actin filaments <ref name="rts4">{{cite web
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| | last =
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| | first =
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| | authorlink =
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| | coauthors =
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| | title =Listeria
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| | work =
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| | publisher =MicrobeWiki.Kenyon.edu
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| | date = 16 August 2006
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| | url =http://microbewiki.kenyon.edu/index.php?title=Listeria&oldid=5472
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| | format =
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| | accessdate = 2007-03-07 }}</ref> with the promotion of virulence factor ActA<ref name="rts2"/>. The comet forms in a polar manner <ref name="rtsjournal2">{{cite journal | quotes=no |author= Laine, R.O. et al |year=1998|url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=108414|title= Gelsolin, a Protein That Caps the Barbed Ends and Severs Actin Filaments, Enhances the Actin-Based Motility of Listeria monocytogenes in Host Cells |journal=Infection and Immunity |volume=66(8) |pages=3775-3782}}</ref> and aids the bacteria's migration to the host cell's outer membrane. Gelsolin, an actin filament severing protein, localizes at the tail of ''Listeria'' and accelerates the bacterium's motility.<ref name="rtsjournal2"/> Once at the cell surface, the actin-propelled ''Listeria'' pushes against the cell's membrane to form protrusions called [[filopod]]s<ref name="rts1"/> or "rockets". The protrusions are guided by the cell's leading edge <ref name="rtsjournal3">{{cite journal | quotes=no |author= Galbraith, C.G. et al |year=2007|url= |title= Polymerizing Actin Fibers Position Integrins Primed to Probe for Adhesion Sites |journal=Science |volume=315 |pages=992-995}}</ref>to contact adjacent cells which subsequently engulf the ''Listeria'' rocket and the process is repeated, perpetuating the infection.<ref name="rts2"/> Once phagocytosed, the ''Listeria'' is never again extracellular: it is an intracytoplasmic parasite <ref name="rtsjournal1"/> like ''[[Shigella flexneri]]'' and ''[[Rickettsia]]''.<ref name="rts2"/>
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| ==Epidemiology==
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| The [[Center for Science in the Public Interest]] has published a list of foods that have sometimes caused outbreaks of Listeria: hot dogs, deli meats, raw milk, cheeses (particularly soft-ripened cheeses like feta, Brie, Camembert, blue-veined, or Mexican-style “queso blanco”), raw and cooked poultry, raw meats, ice cream, raw vegetables, raw and smoked fish.<ref>[[Center for Science in the Public Interest]] - [http://www.cspinet.org/nah/10_99/fsg_meet_the_bugs.htm Nutrition Action Healthletter - Food Safety Guide - Meet the Bugs]</ref>
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| ==Prevention==
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| The prevention of Listeria as a food illness involves effective sanitizing of food contact surfaces. [[Alcohol]] has proven to be an effective topical sanitizer against Listeria. [[Quaternary ammonium]] can be used in conjunction with alcohol as a food contact safe sanitizer with increased duration of the sanitizing action. Nonflammable Alcohol Vapour in carbon dioxide [[NAV-CO2]] systems or sodium hypochlorite are frequently used to sanitize surfaces to prevent Listeria.
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| ==Modern Relevance/Future Research==
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| Listeriosis is an opportunistic pathogen: it is most prevalent in the elderly, pregnant mothers, and AIDS patients. With improved healthcare leading to a growing elderly population and extended life expectancies for AIDS patients, physicians are more likely to encounter this otherwise rare infection (only 0.7 per 100,000 healthy people are infected with virulent ''Listeria'' each year).<ref name="rts1"/> Better understanding the cell biology of Listeria infections, including relevant virulence factors, may help us better treat Listeriosis and other intracytoplasmic parasites. Researchers are now investigating the use of ''Listeria'' as a cancer vaccine, taking advantage of its "ability induce potent innate and adaptive immunity."<ref name="rts4"/>
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| ==Treatment==
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| Antibiotics effective against ''Listeria'' species include [[Ampicillin]], [[vancomycin]], [[ciprofloxacin]], [[linezolid]], [[azithromycin]], and [[cotrimoxazole]].
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| ===Future treatment options===
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| Intralytix has created a virus spray with bacteriophages to be applied to food for the prevention of [[Listeriosis]] by killing six strains of ''[[Listeria monocytogenes|L. monocytogenes]]'' bacterium.<ref>[[Associated Press]] - [http://www.livescience.com/othernews/ap_060821_virus_food.html Viruses Approved for Treating Food]</ref> EBI Food Safety has created and put a similar product on the market, LISTEX™ P100. LISTEX™ P100 prevents Listerios in food by using bacteriophages for killing Listeria. <ref>[[Food Quality News]] - [http://www.foodqualitynews.com/news/ng.asp?n=71423-ebi-bacteriophages-listeria Phage product found effective against Listeria]</ref>
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| ==See also==
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| *[[List of foodborne illness outbreaks]]
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| ==References==
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| <!-- ---------------------------------------------------------------
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| See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for a
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| discussion of different citation methods and how to generate
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| footnotes using the <ref> & </ref> tags and the {{Reflist}} template
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| {{Reflist|2}}
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| ==External links==
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| *[http://www.about-listeria.com/ About Listeria]
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| *[http://www.snopes.com/food/warnings/saralee.asp Snopes article about Listeria in Sara Lee products (December 1998)]
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| [[Category:Gram positive bacteria]]
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| [[Category:Listeriaceae]]
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| [[Category:Overview complete]]
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| [[cs:Listérie]]
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| [[de:Listerien]]
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| [[fr:Listeria]]
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| [[he:Listeria]]
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| [[ja:リステリア]]
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| [[uk:Listeria]]
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