Difference between revisions of "Bacillus species"
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| − | # | + | <big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big> |
| + | <big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big> | ||
| + | [[Bacillus anthracis]] | ||
| + | |||
| + | *''CAR bacillus'' in [[Bacterial infections#CAR bacillus|URT infection in cattle]] and [[Bacterial infections#In Rabbits|URT infection in rabbits]] | ||
| + | |||
| + | * Can cause vascular fragility, leading to [[General Pathology - Haemostasis#Haemorrhagic Disease Due To Vascular Fragility|haemorrhagic disease]]. | ||
| + | |||
| + | ===Overview=== | ||
| + | |||
| + | *Mostly non-pathogenic environmental organisms | ||
| + | *''Bacillus anthracis'' causes anthrax | ||
| + | *Anthrax is a severe disease affecting all mammals worldwide | ||
| + | *Ruminants are highly susceptible to anthrax, dying of a septicaemic form | ||
| + | *Pigs and horses are moderately susceptible, but carnivores are fairly resistant | ||
| + | *''Bacillus licheniformis'' may cause shoradic abortions in cattle and sheep | ||
| + | *''Bacillus cereus'' causes food poisoning in humans and mastitis in cows | ||
| + | |||
| + | |||
| + | ===Characteristics=== | ||
| + | |||
| + | *Large, Gram positive rods | ||
| + | *Produce endospores | ||
| + | *Aerobes or facultative anaerobes | ||
| + | *Grow on non-enriched media | ||
| + | *Motile | ||
| + | *Catalase positive, oxidase negative | ||
| + | *''Bacillus anthracis'' colonies are up to 5mm diameter, flat, dry, grey, with a ground-glass appearance; curled outgrowthsfrom the edge of the colony give a 'medusa head' appearance; non-haemolytic (differentiate from ''Bacillus cereus'') | ||
| + | *''Bacillus licheniformis'' forms dull, rough, wrinkled colonies, with hair-like outgrowths | ||
| + | *Biochemical tests for identification | ||
| + | *Can often tolerate adverse environmental conditions | ||
| + | |||
| + | |||
| + | ===''Bacillus anthracis''=== | ||
| + | |||
| + | * | ||
| + | *Pathogenesis and pathogenicity: | ||
| + | **Saprophyte in soil | ||
| + | **Capsule composed of homopolymer of D-isomer of glutamic acid allows survival in the body by resisting phagocytosis | ||
| + | **Capsule stains mauve with polychrome methylene blue in the MacFadyean's reaction - identify anthrax in blood samples | ||
| + | **Bacilli appear as chains of dark blue, square-ended rods surounded with the capsule | ||
| + | **Extracellular toxin (holotoxin) composed of oedema factor, protective factor and lethal factor | ||
| + | **Oedema factor is an adenylate cyclase which increases intracellular cAMP concetrations, damaging phagocytes | ||
| + | **Protective factor binds to the cell receptor to allow action of the other factors | ||
| + | **The toxin kills phagocytes, increases capillary permeability and interferes with clooting cascade | ||
| + | **Capillary thrombosis; leakage of fluid through damaged capillary endothelium | ||
| + | **Systemic shock from circulatory collapse, haemorrhage and oedema lead to death of the animal | ||
| + | *Clinical signs: | ||
| + | ** | ||
| + | |||
| + | |||
| + | ===''Bacillus licheniformis''=== | ||
| + | |||
| + | *Widespread in the environment | ||
| + | *Associated with food spoilage | ||
| + | *Abortion in cattle and sheep, possibly from spoiled silage or hay | ||
Revision as of 12:50, 17 May 2008
- CAR bacillus in URT infection in cattle and URT infection in rabbits
- Can cause vascular fragility, leading to haemorrhagic disease.
Overview
- Mostly non-pathogenic environmental organisms
- Bacillus anthracis causes anthrax
- Anthrax is a severe disease affecting all mammals worldwide
- Ruminants are highly susceptible to anthrax, dying of a septicaemic form
- Pigs and horses are moderately susceptible, but carnivores are fairly resistant
- Bacillus licheniformis may cause shoradic abortions in cattle and sheep
- Bacillus cereus causes food poisoning in humans and mastitis in cows
Characteristics
- Large, Gram positive rods
- Produce endospores
- Aerobes or facultative anaerobes
- Grow on non-enriched media
- Motile
- Catalase positive, oxidase negative
- Bacillus anthracis colonies are up to 5mm diameter, flat, dry, grey, with a ground-glass appearance; curled outgrowthsfrom the edge of the colony give a 'medusa head' appearance; non-haemolytic (differentiate from Bacillus cereus)
- Bacillus licheniformis forms dull, rough, wrinkled colonies, with hair-like outgrowths
- Biochemical tests for identification
- Can often tolerate adverse environmental conditions
Bacillus anthracis
- Pathogenesis and pathogenicity:
- Saprophyte in soil
- Capsule composed of homopolymer of D-isomer of glutamic acid allows survival in the body by resisting phagocytosis
- Capsule stains mauve with polychrome methylene blue in the MacFadyean's reaction - identify anthrax in blood samples
- Bacilli appear as chains of dark blue, square-ended rods surounded with the capsule
- Extracellular toxin (holotoxin) composed of oedema factor, protective factor and lethal factor
- Oedema factor is an adenylate cyclase which increases intracellular cAMP concetrations, damaging phagocytes
- Protective factor binds to the cell receptor to allow action of the other factors
- The toxin kills phagocytes, increases capillary permeability and interferes with clooting cascade
- Capillary thrombosis; leakage of fluid through damaged capillary endothelium
- Systemic shock from circulatory collapse, haemorrhage and oedema lead to death of the animal
- Clinical signs:
Bacillus licheniformis
- Widespread in the environment
- Associated with food spoilage
- Abortion in cattle and sheep, possibly from spoiled silage or hay