Bacillus anthracis

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iBacillus anthracis

Photomicrograph of Bacillus anthracis (fuchsin-methylene blue spore stain).

Scientific classification

Kingdom:	Bacteria
Phylum:	Firmicutes
Class:	Bacilli
Order:	Bacillales
Family:	Bacillaceae
Genus:	Bacillus
Species:	B. anthracis

Binomial name

Bacillus anthracis
Cohn 1872

Image:B anthracis diagram en.png

Bacillus anthracis is a Gram-positive, 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.<ref name=Sherris>Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9.</ref>

Each cell is about 1 by 6 μms in size.

1 Historical background
2 Pathogenicity
3 Treatment
4 References

[edit] Historical background

B. anthracis was the first bacterium conclusively demonstrated to cause disease, by Robert Koch in 1877.<ref name=Brock>Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0-13-144329-1.</ref> The species name anthracis is from the Greek anthrakis (ἄνθραξ), meaning coal and referring to the most common form of the disease, cutaneous anthrax, in which large black skin lesions are formed.

[edit] Pathogenicity

Under conditions of environmental stress, B. anthracis bacteria naturally produce endospores which rest in the soil and can survive for decades in this state. When ingested by a cattle, sheep, or other herbivores, the bacteria begin to reproduce inside the animal and eventually kill it, then continue to reproduce in its carcass. Once the nutrients are exhausted, new endospores are produced and the cycle repeats.<ref name=Barron>Turnbull PCB (1996). Bacillus. In: Barron's Medical Microbiology (Barron S et al, eds.), 4th ed., Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.</ref>

B. anthracis has as least 89 known strains, ranging from highly virulent strains with biological warfare and bioterrorism applications (Ames and Vollum) to benign strains used for inoculations (Sterne). The strains differ in presence and activity of various genes, determining their virulence and production of antigens and toxins. The form associated with the 2001 anthrax attacks contains a toxin consisting of three proteins: the protective antigen, the edema factor and the lethal factor.

[edit] Treatment

Main article: Anthrax

Infections with B. anthracis can be treated with β-lactam antibiotics such as penicillin, and others which are active against Gram-positive bacteria.