|
|
| (15 intermediate revisions by 3 users not shown) |
| Line 1: |
Line 1: |
| − | ===Overview=== | + | {{frontpage |
| | + | |pagetitle =Bacillus species |
| | + | |pagebody = The ''Bacillus'' species are large, Gram positive rods that produce endospores. They are mostly non-pathogenic environmental organisms. |
| | + | |contenttitle =Content |
| | + | |contentbody =<big><b> |
| | + | <categorytree mode=pages>Bacillus species</categorytree> |
| | + | </b></big> |
| | + | |logo =bugs-logo copy.png |
| | + | }} |
| | | | |
| − | *Mostly non-pathogenic environmental organisms
| + | [[Category:Bacterial Organisms]] |
| − | *''[[Bacillus anthracis]]'' causes anthrax
| + | [[Category:Gram_positive_bacteria]] |
| − | *Anthrax is a severe disease affecting all mammals worldwide
| + | [[Category:Rods]] |
| − | *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 outgrowths from 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 and penetration through damaged mucosa
| |
| − | *Pathogenesis and pathogenicity:
| |
| − | **Spores germinate at site of entry and spread via lymphatics to bloodstream, where they multiply and produce toxin
| |
| − | **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 - WikiBlood|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, [[Haemostasis - Pathology#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 - Pathology#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
| |
| − | **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 - Pathology#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 found in pigs
| |
| − | **Humans
| |
| − | ***Cutaneous anthrax - localised lesion from entrance into abrasion which can cause septicaemia
| |
| − | ***Pulmonary anthrax - inhalation of spores
| |
| − | ***Intestinal anthrax - ingestion of infective material
| |
| − | *Diagnosis:
| |
| − | **Post mortem: bloat, incomplete rigor mortis, ecchymoses, oedema, dark unclotted blood from orifices, blooy fluid in body cavities, splenomegaly
| |
| − | **Blood smear from an ear or tail vein of ruminants, or peritoneal fluid from pigs stained with polychrome methylene blue
| |
| − | **Chains of square-ended blue rods surrounded by mauve capsules
| |
| − | **Culture on blood and MacConkey agar (no growth on MacConkey)
| |
| − | **Biochemical tests
| |
| − | *Treatment:
| |
| − | **High doses of penicillin G or oxytetracylcine
| |
| − | *Control:
| |
| − | **Report suspected cases - notifiable
| |
| − | **Spores destroyed by sterilisation
| |
| − | **Endemic regions:
| |
| − | ***Live Sterne spore vaccine which produces toxin but has no capsule, therefore is non-pathogenic; stimulates protective antibody
| |
| − | ***Chemoprophylaxis with long-acting penicillin
| |
| − | **Non-endemic regions after an outbreak:
| |
| − | ***Movement restrictions
| |
| − | ***Footbath with sporicidal disinfectant
| |
| − | ***Fumigate buildings with formaldehyde
| |
| − | ***Dispose carcases and contaminated material
| |
| − | ***Isolate in-contact animals
| |
| − | | |
| − | ===''Bacillus licheniformis''===
| |
| − | | |
| − | *Widespread in the environment
| |
| − | *Associated with food spoilage
| |
| − | *Abortion in cattle and sheep, possibly from spoiled silage or hay
| |
| − | | |
| − | | |
| − | | |
| − | | |
| − | | |
| − | | |
| − | | |
| − | *''CAR bacillus'' in [[Respiratory Bacterial Infections - Pathology#CAR bacillus|URT infection in cattle]] and [[Respiratory Bacterial Infections - Pathology#In Rabbits|URT infection in rabbits]]
| |
| − | [[Category:Bacteria]][[Category:Gram_positive_bacteria]] | |
