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Bacillus anthracis

 

 
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Bacillus anthracis
 
 
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Bacillus anthracis is a very large bacterium compared to others. It is a Gram-positive
Gram-positive

Gram-positive Bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink....
 spore-forming rod-shaped bacterium, with a width of 1-1.2µm and a length of 3-5µm. It can be grown in an ordinary nutrient medium under aerobic or anaerobic conditions. It bears close genotypical and phenotypical resemblance to Bacillus cereus
Bacillus cereus

Bacillus cereus is an Endemic , soil-dwelling, Gram-positive bacteria, Bacillus, hemolysis bacteria that causes foodborne illness. It is the cause of "Fried rice Syndrome"....
; Bacillus thuringiensis
Bacillus thuringiensis

Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium of the genus Bacillus. Additionally, B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterfly, as well as on the dark surface of plants....
 is also closely related. All three species share cellular dimensions and morphology. All form oval spores located centrally in a non-swollen sporangium.






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Bacillus anthracis is a very large bacterium compared to others. It is a Gram-positive
Gram-positive

Gram-positive Bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink....
 spore-forming rod-shaped bacterium, with a width of 1-1.2µm and a length of 3-5µm. It can be grown in an ordinary nutrient medium under aerobic or anaerobic conditions. It bears close genotypical and phenotypical resemblance to Bacillus cereus
Bacillus cereus

Bacillus cereus is an Endemic , soil-dwelling, Gram-positive bacteria, Bacillus, hemolysis bacteria that causes foodborne illness. It is the cause of "Fried rice Syndrome"....
; Bacillus thuringiensis
Bacillus thuringiensis

Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium of the genus Bacillus. Additionally, B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterfly, as well as on the dark surface of plants....
 is also closely related. All three species share cellular dimensions and morphology. All form oval spores located centrally in a non-swollen sporangium. Bacillus anthracis spores in particular are highly resilient, surviving extremes of temperature, low-nutrient environments, and harsh chemical treatment over decades or centuries.

Historical background

Casimir Davaine
Casimir Davaine

Casimir Davaine was a France physician known for his work in the field of microbiology.In 1850, Davaine along with French dermatologist Pierre Fran?ois Olive Rayer discovered a certain microorganism in the blood of diseased and dying sheep....
 found the bacteria in sick people . B. anthracis was the first bacterium conclusively demonstrated to cause disease, by Robert Koch
Robert Koch

Heinrich Hermann Robert Koch was a German physician. He became famous for isolating Bacillus anthracis , the Mycobacterium tuberculosis and the Vibrio cholerae and for his development of Koch's postulates....
 in 1877. The species name anthracis is from the Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 anthrakis (????a?), meaning coal and referring to the most common form of the disease, cutaneous anthrax, in which large black skin lesion
Lesion

A lesion is any abnormal tissue found on or in an organism, usually damaged by disease or trauma. Lesion is derived from the Latin word laesio which means injury....
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

Horses respond variably to B.anthracis depending on the site of entry. Ingestion tends to lead to a severe enteritis and sepsis. Inoculation in the skin tends to result in a local swelling
Swelling

Swelling can mean:* In medicine:** Swelling is the enlargement of organs caused by accumulation of excess fluid in tissues, called edema.* In engineering:...
 and associated lymphadenitis.

The bacterium can be cultivated in ordinary nutrient medium under aerobic or anaerobic conditions.

Clinical Expression

Three forms of anthrax disease are recognized based on their form of inoculation.
1.) Cutaneous: the most common form (95%), causes a localized inflammatory black necrotic lesion (eschar)
2.) Inhalation: highly fatal and characterized by sudden massive chest edema followed by cardiovascular shock
3.) Gastrointestinal: rare but also fatal (causes death to 25%) type results from ingestion of spores

Treatment

Infections with B. anthracis can be treated with ß-lactam
Beta-lactam

||-||-||-||-||-||-||}A beta-lactam ring or penam is a lactam with a heteroatomic ring structure, consisting of three carbon atoms and one nitrogen atom ....
 antibiotic
Antibiotic

In common usage, an antibiotic is a substance or compound that kills or inhibits the growth of bacteria. Antibiotics belong to the group of antimicrobial compounds used to treat infections caused by microorganisms, including fungus and protozoa....
s such as penicillin
Penicillin

Penicillin is a group of antibiotics derived from Penicillium fungi. They are Beta-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms....
, and others which are active against Gram-positive bacteria.and type a motrin

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