Bacillus anthracis 43698 225157150 2008-07-12T05:04:32Z Beefyt 919455 /* Pathogenicity */ {{Taxobox | color = lightgrey | name = ''Bacillus anthracis'' | image = Bacillus_anthracis.png | image_width = 240px | image_caption = Photomicrograph of ''Bacillus anthracis'' (fuchsin-methylene blue spore stain). | regnum = [[Bacterium|Bacteria]] | phylum = [[Firmicutes]] | classis = [[Bacilli]] | ordo = [[Bacillales]] | familia = [[Bacillaceae]] | genus = ''[[Bacillus]]'' | species = '''''B. anthracis''''' | binomial = ''Bacillus anthracis'' | binomial_authority = Cohn 1872 }} [[Image:B_anthracis_diagram_en.png|right|thumb|240px|Structure of ''Bacillus anthracis''.]] '''''Bacillus anthracis''''' is a [[Gram-positive]], [[Facultative anaerobic organism|facultatively anaerobic]], rod-shaped [[bacterium]] of the genus ''[[Bacillus]]''. An [[endospore]] forming bacterium, ''B. anthracis'' is a natural soil-dwelling organism, as well as the causative agent of [[anthrax disease|anthrax]].<ref name=Sherris>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | publisher = McGraw Hill | year = 2004 | isbn = 0-8385-8529-9 }}</ref> Each cell is about 1 by 6 [[micrometre|μm]] in size. ==Historical background== [[Casimir Davaine]] found the bacteria in sick people <ref>{{cite journal | quotes = no |last=Théodoridès |first=J |authorlink= |year=[[1966]] |month=Apr |title=Casimir Davaine (1812-1882): a precursor of Pasteur |journal=Medical history |volume=10 |issue=2 |pages=155–65 | publisher = | location = | issn = | pmid = 5325873 | bibcode = | oclc =| id = | url = | language = | format = | accessdate = | laysummary = | laysource = | laydate = | quote = }}</ref>. ''B. anthracis'' was the first bacterium conclusively demonstrated to cause disease, by [[Robert Koch]] in 1877.<ref name=Brock>{{cite book | author = Madigan M, Martinko J (editors). | title = Brock Biology of Microorganisms | edition = 11th ed. | publisher = Prentice Hall | year = 2005 | isbn = 0-13-144329-1 }}</ref> The species name ''anthracis'' is from the [[Greek language|Greek]] ''anthrakis'' (ἄνθραξ), meaning ''coal'' and referring to the most common form of the disease, [[cutaneous]] anthrax, in which large black skin [[lesion]]s are formed. When cutaneous anthrax affects a patient a painless, raised nodule forms at the site. As the B. anthracis continues to grow, the cells surrounding the nodule die and the nodule spreads. Eschar, the name given to the enlarged blackened (from the dead cells) lesion comes from a Greek word meaning "charcoal." ==Pathogenicity== Under conditions of environmental stress, ''B. anthracis'' bacteria naturally produce endospores which rest in the soil and can survive for thousands of years in this state. B. anthracis may be inoculated into a wound, inhaled or ingested. In [[ruminants]], the bacterium causes sudden death from [[septicaemia]]. For this reason any ruminants found to have died suddenly and without obvious reason should be treated as a suspected anthrax case. In these event, a blood sample is taken, by a qualified veterinary surgeon, from a superficial vein and subjected to the MacFaydean polychrome methylene blue staining procedure which screens for B.anthracis. Confirmational diagnosis is achieved through [[polymerase chain reaction|PCR]] and [[Immunofluorescence]]. Horses respond variably to B.anthracis depending on the site of entry. Ingestion tends to lead to a severe enteritis and septicaemia. Inoculation in the skin tends to result in a local swelling and associated [[lymphadenitis]]. In pigs, B. anthracis again causes an acute necrotising tonsillitis, or a subacute pharyngeal swelling, or the intestinal disease described in horses. The intestinal disease carries a higher mortality. Dogs and cats seem less susceptible to B.anthracis and require a relative large dose of infectious agent before they begin to show clinical signs. ''B. anthracis'' has at least 89 known [[strain (biology)|strains]], ranging from highly virulent strains with [[biological warfare]] and [[bioterrorism]] applications ([[Ames strain|Ames]] and ''Vollum'') to benign strains used for [[inoculation]]s (''Sterne''). The strains differ in presence and activity of various [[gene]]s, determining their [[virulence]] and production of [[antigen]]s and [[toxin]]s. The form associated with the [[2001 anthrax attacks]] produced both [[anthrax toxin|toxin]] (consisting of three [[protein]]s: [[anthrax toxin|the protective antigen, the edema factor and the lethal factor]]) and a [[Capsule_(microbiology)|capsule]] (consisting of a polymer of glutamic acid). Infection with anthrax requires the presence of all three of these exotoxins.<ref>{{cite journal |author=Dixon TC, Meselson M, Guillemin J, Hanna PC |title=Anthrax |journal=N. Engl. J. Med. |volume=341 |issue=11 |pages=815–26 |year=1999 |pmid=10477781| doi = 10.1056/NEJM199909093411107 <!--Retrieved from CrossRef by DOI bot-->}}</ref> The bacterium can be cultivated in ordinary nutrient medium under aerobic or anaerobic conditions. ==Treatment== {{main|Anthrax}} Infections with ''B. anthracis'' can be treated with [[Beta-lactam|β-lactam]] [[antibiotic]]s such as [[penicillin]], and others which are active against Gram-positive bacteria.<ref>{{cite journal |author = Barnes JM |title=Penicillin and ''B. anthracis''. |journal= J Path Bacteriol |volume=194|year=1947|pages=113 |doi=10.1002/path.1700590113}}</ref> ==External links== * [http://pathema.jcvi.org/cgi-bin/Bacillus/PathemaHomePage.cgi Pathema-''Bacillus'' Resource] ==References== <!-- --------------------------------------------------------------- See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for a discussion of different citation methods and how to generate footnotes using the <ref> & </ref> tags and the {{Reflist}} template -------------------------------------------------------------------- --> {{Reflist}} [[Category:Bacillaceae]] [[cs:Bacillus anthracis]] [[de:Bacillus anthracis]] [[es:Bacillus anthracis]] [[fr:Bacillus anthracis]] [[ga:Bacillus anthracis]] [[id:Bacillus anthracis]] [[he:Bacillus anthracis]] [[hu:Bacillus anthracis]] [[nl:Bacillus anthracis]] [[ja:炭疽菌]] [[pt:Bacillus anthracis]] [[ro:Bacillus anthracis]] [[tr:Bacillus anthracis]] [[uk:Bacillus anthracis]] [[zh:炭疽桿菌]]