Anthrax causes: Difference between revisions
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[[B. anthracis]], the causative agent of anthrax, is a 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]]. 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. Also characteristic is the square-ended appearance traditionally associated with [[B. anthracis]] vegetative cells, although this may not always be very clear. In the presence of [[oxygen]], 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]]; this does not swell the [[sporangium]] and is generally situated centrally, sometimes sub terminally.<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref> 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> | [[B. anthracis]], the causative agent of anthrax, is a 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]]. 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. Also characteristic is the square-ended appearance traditionally associated with [[B. anthracis]] vegetative cells, although this may not always be very clear. In the presence of [[oxygen]], 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]]; this does not swell the [[sporangium]] and is generally situated centrally, sometimes sub terminally.<ref name=WHO>{{cite web | title = Anthrax in Humans and Animals | url = http://www.who.int/csr/resources/publications/anthrax_web.pdf }}</ref> 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> | ||
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). | 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> | ||
==Origin== | ==Origin== | ||
Revision as of 11:35, 18 July 2014
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Overview
Taxonomy
Bacteria; Archaebacteria; Firmicutes; Bacilli; Bacillales; Bacillaceae; Bacillus; anthracis; Bacillus anthracis
Biology
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B. anthracis, the causative agent of anthrax, is a 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. In blood smears, 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. Also characteristic is the square-ended appearance traditionally associated with B. anthracis vegetative cells, although this may not always be very clear. In the presence of oxygen, 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; this does not swell the sporangium and is generally situated centrally, sometimes sub terminally.[3] 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.[4]
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 factors of B. anthracis. The capsule is also a primary diagnostic aid.[3] 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).[5]
Origin
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.
Tropism
Natural Reservoir
Natural reservoirs of Bacillus anthracis includes:
- Humans
- Mammals
- Herbivores
- Reptiles
- Birds
References
- ↑ "http://phil.cdc.gov/phil/details.asp". External link in
|title=(help) - ↑ "http://phil.cdc.gov/phil/details.asp". External link in
|title=(help) - ↑ 3.0 3.1 "Anthrax in Humans and Animals" (PDF).
- ↑ Sean V. Shadomy & Theresa L. Smith (2008). "Zoonosis update. Anthrax". Journal of the American Veterinary Medical Association. 233 (1): 63–72. doi:10.2460/javma.233.1.63. PMID 18593313. Unknown parameter
|month=ignored (help) - ↑ Mahtab Moayeri & Stephen H. Leppla (2004). "The roles of anthrax toxin in pathogenesis". Current opinion in microbiology. 7 (1): 19–24. doi:10.1016/j.mib.2003.12.001. PMID 15036135. Unknown parameter
|month=ignored (help)