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*Characteristics:
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**Normal inhabitant of mammalian gut; cannot invade normal tissue
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**Pleimorphic - long and filamentous or short cocci
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{| cellpadding="10" cellspacing="0" border="1"
**Fermentative
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| Also known as:
**Haemolytic on blood agar
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| ''F.necrophorum''
**Grey, round, shiny colonies
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|-
**Three biotypes: biotype A has greatest haemolytic activity and virulence
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|}
*Pathogenesis and pathogenicity:
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**Primary pathogen in various diseases of farm animals
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**Mixed bacterial infections
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''F.necrophorum'' is a [[Pathogenic anaerobic non-spore-forming Gram-negative species - Overview|pathogenic, anaerobic, non-spore-forming Gram-negative bacteria]]. It is a normal inhabitant of the mammalian gut and cannot invade normal tissue.
**Can be secondary to [[Infectious Bovine Rhinotracheitis|IBR]]
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**Extracellular haemolysin contributes to infection
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==Characteristics==
**Heat-stable leucocidin - correlated with biotype and virulence
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''F.necrophorum'' is pleimorphic and is either long and filamentous or a short cocci. It is fermentative and haemolytic on blood agar. It produces grey, round and shiny colonies. There are three biotypes, biotype A has the greatest haemolytic activity and virulence.
**Cytoplasmic toxin - haemolytic  
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**LPS endotoxin causes host damage
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==Pathogenesis and pathogenicity==
**Antibodiy levels rise with age, suggesting that these are not protective
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''F.necrophorum'' is a primary pathogen in various diseases of farm animals. It forms mixed bacterial infections and can be secondary to [[Infectious Bovine Rhinotracheitis|IBR]].
*[[Calf Diphtheria|Calf diphtheria]]/necrotic laryngitis [[Respiratory Bacterial Infections - Pathology#In Cattle|in cattle]]:
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Extracellular haemolysin contributes to infection and heat-stable leucocidin is correlated with biotype and virulence. Cytoplasmic toxin is haemolytic and LPS endotoxin causes host damage.
**Necrobacillosis of mouth and pharynx of young calves
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Antibody levels to ''F.necrophorum'' rise with age, suggesting that these are not protective.
**Pharyngitis and [[Larynx Inflammatory - Pathology#Infectious causes of laryngitis|laryngitis]]
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**Associated with bucket feeding where buckets are contaminated with faeces
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''F.necrophorum'' is associated with bucket feeding, where buckets are contaminated with faeces. Bacteria enter through abrasions in the mucosa of the pharynx and larynx and cause fever, depression, anorexia, salivation, respiratory distress and halitosis. Aspiration of necrotic material into lungs may cause fatal [[Lungs Inflammatory - Pathology#Infectious causes of neumonia|bronchopneumonia]].
**Bacteria enter through abrasions in the mucosa of the pharynx and larynx
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**Fever, depression, anorexia, salivation, respiratory distress and halitosis
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''F.necrophorum'' causes a number of necrotic wound infections often in association with facultative anaerobes.
**Aspiration of necrotic material into lungs may cause fatal [[Lungs Inflammatory - Pathology#Infectious causes of neumonia|bronchopneumonia]]
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It causes;
**Treatment: potentiated sulphonamides or tetracyclines
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*Bovine liver abscesses:
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'''Cows'''
**Sudden change in diet to a high grain diet causes ruminal acidosis and rumenitis
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[[Calf Diphtheria|Calf diphtheria]] or necrotic laryngitis [[Respiratory Bacterial Infections - Pathology#In Cattle|in cattle]] and necrobacillosis of the mouth and pharynx of young calves. Also, [[Bovine liver abscesses]] and localised necrosis and scab formation of the teat orifice and sphincter of dairy cows.
**Ulceration of rumenal mucosa and colonisation by ''F. necrophorum'' and [[Arcanobacter pyogenes|''Arcanobacter pyogenes'']]
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**Emboli carry organisms to the liver via the portal vein
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'''Pigs'''
**Focal necrosis and abscess formation in liver
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[[Necrotic rhinitis]] in pigs.
**Putrid smell
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**Rarely show clinical signs
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'''Sheep'''
**Management important
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Interdigital dermatitis ([[Bacterial skin infections - Pathology#Bacterial pododermatitis|pododermatitis]]) in sheep in association with ''D. nodosus'' and [[Arcanobacter pyogenes|''Arcanobacter pyogenes'']], predisposing to footrot. It also causes [[Respiratory Bacterial Infections - Pathology#Laryngeal chondritis|laryngeal chondritis]] in sheep and mixed infections in heel abscesses.
*Necrotic rhinitis of pigs:
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**Sporadic condition in young pigs
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''F.necrophorum'' is also involved in; [[Thrush - Hoof|Hoof thrush]]; Mixed infections in [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]; Mixed infections in aspiration pneumonia and in bovine traumatic reticuloperitonitis and pericarditis; [[Bacterial skin infections - Pathology#Subcutaneous abscesses|subcutaneous abscesses]] due to cat bites; [[Nasal Cavity Inflammatory - Pathology#Chronic rhinitis|chronic fibronecrotic rhinitis]]; [[Bones Inflammatory - Pathology#Osteitis|Osteitis]]; [[Contagious Footrot]]; [[Necrobacillosis]] and [[Laryngeal Chondritis]]
**Suppuration and necrosis of snout
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**''F. necrophorum'' and other organisms enter through abrasions in snout mucosa
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==Treatment==
**Facial swelling, sneezing, putri nasal discharge
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Treatment against ''F.necrophorum'' includes potentiated sulphonamides or tetracyclines.
**Chronic infection - faical deformity
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**Treat with potentiated sulphonamides
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**Occasional pharyngitis/laryngitis [[Respiratory Bacterial Infections - Pathology#In Pigs|in pigs]]
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*Thrush of the hoof:
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**Necrosis of horse hoof associated with poor hygiene, wet conditions
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**''F. necrophorum'' secondary to hoof damage causes localised inflammatory response
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**Thrush especially of hind feet, with putrid discharge in sulci
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**Provide dry, clean bedding
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*Black spot of bovine teats
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**Localised necrosis and scab formation of teat orifice and sphincter of dairy cows due to ''F. necrophorum''
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**May predispose to mastitis
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*Necrotic wound infections often in association with facultative anaerobes
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*Interdigital dermatitis ([[Bacterial skin infections - Pathology#Bacterial pododermatitis|pododermatitis]]) in sheep in association with ''D. nodosus'' and [[Arcanobacter pyogenes|''Arcanobacter pyogenes'']], predisposing to footrot
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*Causes [[Respiratory Bacterial Infections - Pathology#Laryngeal chondritis|laryngeal chondritis]] in sheep
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*Mixed infections in heel abscesses in sheep
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*Mixed infections in [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
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*Mixed infections in aspiration pneumonia and in bovine traumatic reticuloperitonitis and pericarditis
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*Involved in [[Bacterial skin infections - Pathology#Subcutaneous abscesses|subcutaneous abscesses]] due to cat bites
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*May be involved in [[Nasal Cavity Inflammatory - Pathology#Chronic rhinitis|chronic fibronecrotic rhinitis]]
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*[[Bones Inflammatory - Pathology#Osteitis|Osteitis]]
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*[[Contagious Footrot]]
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*[[Necrobacillosis]]
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*[[Laryngeal Chondritis]]
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[[Category:Cattle]][[Category:Pig]][[Category:Horse]][[Category:Sheep]]
   
[[Category:Pathogenic anaerobic non-spore-forming Gram-negative ]]
 
[[Category:Pathogenic anaerobic non-spore-forming Gram-negative ]]
 
[[Category:To_Do_-_Bacteria]]
 
[[Category:To_Do_-_Bacteria]]
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