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> | ||
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| + | *''CAR bacillus'' in [[Bacterial infections#CAR bacillus|URT infection in cattle]] and [[Bacterial infections#In Rabbits|URT infection in rabbits]] | ||
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| + | |||
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| + | ===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 outgrowth sfrom 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''=== | ||
| + | |||
| + | *Epidemiology: | ||
| + | **Saprophyte in soil | ||
| + | **Endospore formation allows persistence and spread | ||
| + | **Endospores survive decades in the soil | ||
| + | **Outbreaks in herbivores grazing pastures contaminated by spores from buried carcases | ||
| + | **Infection usually by ingestion of spores | ||
| + | *Pathogenesis and pathogenicity: | ||
| + | **Capsule and toxin (encoded by separate plasmids) required for virulence | ||
| + | **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 antigen and lethal factor | ||
| + | **Oedema factor is an adenylate cyclase which increases intracellular cAMP concetrations, causing fluid accumulation and damaging neutrophils | ||
| + | **Lethal factor causes release of cytokines from macrophages | ||
| + | **Protective antigen binds to the cell receptor to allow action of the other factors | ||
| + | **The toxin kills phagocytes, increases capillary permeability and interferes with clotting cascade | ||
| + | **Capillary thrombosis; leakage of fluid through damaged capillary endothelium | ||
| + | **Systemic shock from circulatory collapse, [[General Pathology - Haemostasis#Haemorrhagic Disease Due To Vascular Fragility|haemorrhagic disease]] and oedema lead to death of the animal | ||
| + | **Severe systemic disease that can result in [[Intestines - Fibrinous/ Haemorrhagic Enteritis#Bacterial septicaemia and enteritis|enteritis]] | ||
| + | **Causes tissues to darken and swell due to oedema and necrosis | ||
| + | *Clinical signs: | ||
| + | **Cattle/sheep: | ||
| + | ***Fatal peracute septicaemia | ||
| + | ***Animals usually found dead | ||
| + | ***Pyrexia, depression, congested mucous membranes and petechiae before death | ||
| + | ***Abortion, subcutaneous oedema and dysentry in animals surviving more that one day | ||
| + | ***Post mortem: bloat, incomplete rigor mortis, ecchymoses, oedema, dark unclotted blood, blooy fluid in body cavities, splenomegaly | ||
| + | **Pigs: | ||
| + | ***Subacute anthrax with oedematous swelling of throat, head and regional lymph nodes | ||
| + | ***Intestinal form with high mortality - dysentry due to haemorrhagic enteric lesions | ||
| + | ****[[Peritoneal cavity - inflammatory#In pigs|Peritonitis]] | ||
| + | **Horses: | ||
| + | ***Subacute anthrax with subcutaneous oedema of thorax, abdomen and legs following entrance of spores into abrasions | ||
| + | ***Septicaemia with colic and dysentry due to haemorrhagic enteritis from ingestion of spores; ecchymoses and splenomegaly | ||
| + | **Dogs | ||
| + | ***Rarely affected, but similar disease to that foung in pigs | ||
| + | |||
| + | |||
| + | |||
| + | ===''Bacillus licheniformis''=== | ||
| + | |||
| + | *Widespread in the environment | ||
| + | *Associated with food spoilage | ||
| + | *Abortion in cattle and sheep, possibly from spoiled silage or hay | ||
| + | |||
| + | |||
| + | ===''Bacillus cereus''=== | ||
| + | |||
| + | *Mastitis in cattle | ||
| + | *Food poisoning and eye infections in humans | ||
Revision as of 13:23, 17 May 2008
- CAR bacillus in URT infection in cattle and URT infection in rabbits
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 outgrowth sfrom 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
- Epidemiology:
- Saprophyte in soil
- Endospore formation allows persistence and spread
- Endospores survive decades in the soil
- Outbreaks in herbivores grazing pastures contaminated by spores from buried carcases
- Infection usually by ingestion of spores
- Pathogenesis and pathogenicity:
- Capsule and toxin (encoded by separate plasmids) required for virulence
- 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 antigen and lethal factor
- Oedema factor is an adenylate cyclase which increases intracellular cAMP concetrations, causing fluid accumulation and damaging neutrophils
- Lethal factor causes release of cytokines from macrophages
- Protective antigen binds to the cell receptor to allow action of the other factors
- The toxin kills phagocytes, increases capillary permeability and interferes with clotting cascade
- Capillary thrombosis; leakage of fluid through damaged capillary endothelium
- Systemic shock from circulatory collapse, haemorrhagic disease and oedema lead to death of the animal
- Severe systemic disease that can result in enteritis
- Causes tissues to darken and swell due to oedema and necrosis
- Clinical signs:
- Cattle/sheep:
- Fatal peracute septicaemia
- Animals usually found dead
- Pyrexia, depression, congested mucous membranes and petechiae before death
- Abortion, subcutaneous oedema and dysentry in animals surviving more that one day
- Post mortem: bloat, incomplete rigor mortis, ecchymoses, oedema, dark unclotted blood, blooy fluid in body cavities, splenomegaly
- Pigs:
- Subacute anthrax with oedematous swelling of throat, head and regional lymph nodes
- Intestinal form with high mortality - dysentry due to haemorrhagic enteric lesions
- Horses:
- Subacute anthrax with subcutaneous oedema of thorax, abdomen and legs following entrance of spores into abrasions
- Septicaemia with colic and dysentry due to haemorrhagic enteritis from ingestion of spores; ecchymoses and splenomegaly
- Dogs
- Rarely affected, but similar disease to that foung in pigs
- Cattle/sheep:
Bacillus licheniformis
- Widespread in the environment
- Associated with food spoilage
- Abortion in cattle and sheep, possibly from spoiled silage or hay
Bacillus cereus
- Mastitis in cattle
- Food poisoning and eye infections in humans