Author, Donkey, Bureaucrats, Administrators
53,803
edits
Changes
Created page with '*Characteristics: **Normal inhabitant of mammalian gut; cannot invade normal tissue **Pleimorphic - long and filamentous or short cocci **Fermentative **Haemolytic on blood agar …'
*Characteristics:
**Normal inhabitant of mammalian gut; cannot invade normal tissue
**Pleimorphic - long and filamentous or short cocci
**Fermentative
**Haemolytic on blood agar
**Grey, round, shiny colonies
**Three biotypes: biotype A has greatest haemolytic activity and virulence
*Pathogenesis and pathogenicity:
**Primary pathogen in various diseases of farm animals
**Mixed bacterial infections
**Can be secondary to [[Respiratory Viral Infections - Pathology#In Cattle|IBR]]
**Extracellular haemolysin contributes to infection
**Heat-stable leucocidin - correlated with biotype and virulence
**Cytoplasmic toxin - haemolytic
**LPS endotoxin causes host damage
**Antibodiy levels rise with age, suggesting that these are not protective
*Calf diphtheria/necrotic laryngitis [[Respiratory Bacterial Infections - Pathology#In Cattle|in cattle]]:
**Necrobacillosis of mouth and pharynx of young calves
**Pharyngitis and [[Larynx Inflammatory - Pathology#Infectious causes of laryngitis|laryngitis]]
**Associated with bucket feeding where buckets are contaminated with faeces
**Bacteria enter through abrasions in the mucosa of the pharynx and larynx
**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]]
**Treatment: potentiated sulphonamides or tetracyclines
*Bovine liver abscesses:
**Sudden change in diet to a high grain diet causes ruminal acidosis and rumenitis
**Ulceration of rumenal mucosa and colonisation by ''F. necrophorum'' and [[Arcanobacter pyogenes|''Arcanobacter pyogenes'']]
**Emboli carry organisms to the liver via the portal vein
**Focal necrosis and abscess formation in liver
**Putrid smell
**Rarely show clinical signs
**Management important
*Necrotic rhinitis of pigs:
**Sporadic condition in young pigs
**Suppuration and necrosis of snout
**''F. necrophorum'' and other organisms enter through abrasions in snout mucosa
**Facial swelling, sneezing, putri nasal discharge
**Chronic infection - faical deformity
**Treat with potentiated sulphonamides
**Occasional pharyngitis/laryngitis [[Respiratory Bacterial Infections - Pathology#In Pigs|in pigs]]
*Thrush of the hoof:
**Necrosis of horse hoof associated with poor hygiene, wet conditions
**''F. necrophorum'' secondary to hoof damage causes localised inflammatory response
**Thrush especially of hind feet, with putrid discharge in sulci
**Provide dry, clean bedding
*Black spot of bovine teats
**Localised necrosis and scab formation of teat orifice and sphincter of dairy cows due to ''F. necrophorum''
**May predispose to mastitis
*Necrotic wound infections often in association with facultative anaerobes
*Interdigital dermatitis ([[Bacterial skin infections - Pathology#Bacterial pododermatitis|pododermatitis]]) in sheep in association with ''D. nodosus'' and [[Arcanobacter pyogenes|''Arcanobacter pyogenes'']], predisposing to footrot
*Causes [[Respiratory Bacterial Infections - Pathology#Laryngeal chondritis|laryngeal chondritis]] in sheep
*Mixed infections in heel abscesses in sheep
*Mixed infections in [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
*Mixed infections in aspiration pneumonia and in bovine traumatic reticuloperitonitis and pericarditis
*Involved in [[Bacterial skin infections - Pathology#Subcutaneous abscesses|subcutaneous abscesses]] due to cat bites
*May be involved in [[Nasal Cavity Inflammatory - Pathology#Chronic rhinitis|chronic fibronecrotic rhinitis]]
*[[Bones Inflammatory - Pathology#Osteitis|Osteitis]]
**Normal inhabitant of mammalian gut; cannot invade normal tissue
**Pleimorphic - long and filamentous or short cocci
**Fermentative
**Haemolytic on blood agar
**Grey, round, shiny colonies
**Three biotypes: biotype A has greatest haemolytic activity and virulence
*Pathogenesis and pathogenicity:
**Primary pathogen in various diseases of farm animals
**Mixed bacterial infections
**Can be secondary to [[Respiratory Viral Infections - Pathology#In Cattle|IBR]]
**Extracellular haemolysin contributes to infection
**Heat-stable leucocidin - correlated with biotype and virulence
**Cytoplasmic toxin - haemolytic
**LPS endotoxin causes host damage
**Antibodiy levels rise with age, suggesting that these are not protective
*Calf diphtheria/necrotic laryngitis [[Respiratory Bacterial Infections - Pathology#In Cattle|in cattle]]:
**Necrobacillosis of mouth and pharynx of young calves
**Pharyngitis and [[Larynx Inflammatory - Pathology#Infectious causes of laryngitis|laryngitis]]
**Associated with bucket feeding where buckets are contaminated with faeces
**Bacteria enter through abrasions in the mucosa of the pharynx and larynx
**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]]
**Treatment: potentiated sulphonamides or tetracyclines
*Bovine liver abscesses:
**Sudden change in diet to a high grain diet causes ruminal acidosis and rumenitis
**Ulceration of rumenal mucosa and colonisation by ''F. necrophorum'' and [[Arcanobacter pyogenes|''Arcanobacter pyogenes'']]
**Emboli carry organisms to the liver via the portal vein
**Focal necrosis and abscess formation in liver
**Putrid smell
**Rarely show clinical signs
**Management important
*Necrotic rhinitis of pigs:
**Sporadic condition in young pigs
**Suppuration and necrosis of snout
**''F. necrophorum'' and other organisms enter through abrasions in snout mucosa
**Facial swelling, sneezing, putri nasal discharge
**Chronic infection - faical deformity
**Treat with potentiated sulphonamides
**Occasional pharyngitis/laryngitis [[Respiratory Bacterial Infections - Pathology#In Pigs|in pigs]]
*Thrush of the hoof:
**Necrosis of horse hoof associated with poor hygiene, wet conditions
**''F. necrophorum'' secondary to hoof damage causes localised inflammatory response
**Thrush especially of hind feet, with putrid discharge in sulci
**Provide dry, clean bedding
*Black spot of bovine teats
**Localised necrosis and scab formation of teat orifice and sphincter of dairy cows due to ''F. necrophorum''
**May predispose to mastitis
*Necrotic wound infections often in association with facultative anaerobes
*Interdigital dermatitis ([[Bacterial skin infections - Pathology#Bacterial pododermatitis|pododermatitis]]) in sheep in association with ''D. nodosus'' and [[Arcanobacter pyogenes|''Arcanobacter pyogenes'']], predisposing to footrot
*Causes [[Respiratory Bacterial Infections - Pathology#Laryngeal chondritis|laryngeal chondritis]] in sheep
*Mixed infections in heel abscesses in sheep
*Mixed infections in [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
*Mixed infections in aspiration pneumonia and in bovine traumatic reticuloperitonitis and pericarditis
*Involved in [[Bacterial skin infections - Pathology#Subcutaneous abscesses|subcutaneous abscesses]] due to cat bites
*May be involved in [[Nasal Cavity Inflammatory - Pathology#Chronic rhinitis|chronic fibronecrotic rhinitis]]
*[[Bones Inflammatory - Pathology#Osteitis|Osteitis]]