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| __NOTOC__
| | #REDIRECT [[Bacillus anthracis]] |
| {{Anthrax}}
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| {{CMG}}; {{AE}} {{JS}}
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| ==Overview==
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| The causative agent of anthrax is [[B. anthracis]], a nonmotile, [[Gram-positive]], [[aerobic]] or facultatively anaerobic, [[endospore]]-forming, [[rod]]-shaped [[bacterium]]. The [[spores]] of [[B. anthracis]], which can remain dormant in the environment for decades, are the [[infectious]] form, but vegetative [[B. anthracis]] rarely causes disease.<ref>{{Cite journal | author = [[Sean V. Shadomy]] & [[Theresa L. Smith]] | title = Zoonosis update. Anthrax | journal = [[Journal of the American Veterinary Medical Association]] | volume = 233 | issue = 1 | pages = 63–72 | year = 2008 | month = July | doi = 10.2460/javma.233.1.63 | pmid = 18593313}}</ref> The [[natural reservoir]]s of [[Bacillus anthracis]] includes humans, mammals, herbivores, reptiles, and birds.
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| ==Taxonomy==
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| [[Bacterium|Bacteria]]; [[Archaebacteria]]; [[Firmicutes]]; [[Bacilli]]; [[Bacillales]]; [[Bacillaceae]]; [[Bacillus]]; anthracis; Bacillus anthracis
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| ==Biology==
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| {| style="float: right;"
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| | [[File:AnthraxCauses2.png|200px|thumb|none| Photomicrograph depicting a number of Gram-positive, endospore-forming Bacillus anthracis bacteria<SMALL>Courtesy: ''[http://phil.cdc.gov/phil/home.asp Public Health Image Library (PHIL), Centers for Disease Control and Prevention (CDC)]''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
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| | [[File:AnthraxCauses1.jpg|200px|thumb|none| Scanning electron micrograph (SEM) depicted spores from the Sterne strain of Bacillus anthracis bacteria<SMALL>Courtesy: ''[http://phil.cdc.gov/phil/home.asp Public Health Image Library (PHIL), Centers for Disease Control and Prevention (CDC)]''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
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| [[B. anthracis]], the causative agent of [[anthrax]], is a nonmotile, [[Gram-positive]], [[aerobic]] or facultatively [[anaerobic]], [[endospore]]-forming, [[rod]]-shaped [[bacterium]] approximately 4 μm by 1 μm, although under the microscope it frequently appears in chains of [[cells]]. Like other [[Bacillus]], [[Bacillus anthracis]] is saprophyte, being able to live in vegetations, air, water and soil.<ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| These [[bacterial]] [[cells]] may occur isolated, form groups of 2 or more [[cells]] in the body, or long chains in cultures.<ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref> In [[blood smear]]s, smears of tissues or lesion fluid from diagnostic specimens, these chains are two to a few cells in length. In smears made from [[in vitro]] cultures, they can appear as endless strings of [[cells]] - responsible for the characteristic tackiness of the colonies and for the flocculating nature of broth cultures. Cell cultures appear as a large, grey and curled structure, resembling a "medusa head".<ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| [[B. anthracis]] have a characteristic square-ended appearance, traditionally associated with its vegetative state, although this may not always be very clear. In the presence of [[oxygen]], mostly at 32 - 35 ºC, and towards the end of the exponential phase of growth, one ellipsoidal [[spore]] (approximately 2 μm by 1 μm in size) is formed in each [[cell]].<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref><ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| The [[spores]] of [[B. anthracis]], which can remain dormant in the environment for decades, being resistant to heat and disinfectants, are the [[infectious]] form, but vegetative [[B. anthracis]] rarely causes disease.<ref>{{Cite journal | author = [[Sean V. Shadomy]] & [[Theresa L. Smith]] | title = Zoonosis update. Anthrax | journal = [[Journal of the American Veterinary Medical Association]] | volume = 233 | issue = 1 | pages = 63–72 | year = 2008 | month = July | doi = 10.2460/javma.233.1.63 | pmid = 18593313}}</ref><ref name="BhatnagarBatra2001">{{cite journal|last1=Bhatnagar|first1=Rakesh|last2=Batra|first2=Smriti|title=Anthrax Toxin|journal=Critical Reviews in Microbiology|volume=27|issue=3|year=2001|pages=167–200|issn=1040-841X|doi=10.1080/20014091096738}}</ref>
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| In the absence of [[oxygen]] and under a high partial pressure of Co2, in the presence of [[bicarbonate]], the vegetative [[cell]] secretes its [[polypeptide]] [[capsule]], and it is one of the two established [[in vivo]] [[virulence factor]]s of [[B. anthracis]]. The [[capsule]] is also a primary [[diagnostic]] aid.<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref> Protective [[antigen]] (PA) and [[edema]] factor (EF) combine to form [[edema]] toxin (ET) and PA and lethal factor (LF) combine to form lethal toxin (LT).<ref>{{Cite journal | author = [[Mahtab Moayeri]] & [[Stephen H. Leppla]] | title = The roles of anthrax toxin in pathogenesis | journal = [[Current opinion in microbiology]] | volume = 7 | issue = 1 | pages = 19–24 | year = 2004 | month = February | doi = 10.1016/j.mib.2003.12.001 | pmid = 15036135}}</ref><ref name=CDC>{{cite web | title = Centers for Disease Control and Prevention Expert Panel Meetings on Prevention and Treatment of Anthrax in Adults | url = http://wwwnc.cdc.gov/eid/article/20/2/13-0687_article }}</ref>
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| ==Origin==
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| [[Anthrax]] is thought to have originated in Egypt and Mesopotamia. Many scholars think that in Moses’ time, during the 10 plagues of Egypt, [[anthrax]] may have caused what was known as the fifth [[plague]], described as a sickness affecting horses, cattle, sheep, camels and oxen.
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| ==Tropism==
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| After entering the body (through the skin, lungs, gastrointestinal tract or by injection) B. anthracis spores are believed to germinate locally or be transported by phagocytic cells to the lymphatics and regional lymph nodes, where they germinate.
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| ==Natural Reservoir==
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| [[Natural reservoir]]s of [[Bacillus anthracis]] includes:<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref>
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| * Humans
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| * Mammals
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| * Herbivores
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| * Reptiles
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| * Birds
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| ==References==
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| {{reflist|2}}
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