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| − | <big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
| + | #REDIRECT[[:Category:Actinomycetes]] |
| − | <big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
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| − | *Cause [[Peritoneal cavity - inflammatory#In dogs|peritonitis in dogs]] and [[Peritoneal cavity - inflammatory#In cattle|peritonitis in cattle]] and [[Peritoneal cavity - inflammatory#In pigs|peritonitis in pigs]]
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| − | *''Nocardia'' is involved in [[Peritoneal cavity - inflammatory#In dogs|peritonitis]] and [[Bacterial infections#Nocardiosis|pleuritis]] in dogs
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| − | *''Micropolyspora faeni and Thermactinomyces vulgaris'' in [[Bronchi and bronchioles - inflammatory#Extrinsic Allergic Bronchio-alveolitis|Bovine Farmers Lung]]
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| − | *''Thermactinomyces vulgaris'' may cause [[Bronchi and bronchioles - inflammatory#Chronic obstructive pulmonary disease (COPD)|COPD]]
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| − | * ''Actinomyces'' may cause [[General Pathology - Chronic Inflammation#Granulomatous Inflammation|granulomatous inflammation]].
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| − | ** E.g. ''Actinomyces bovis'' -the cause of [[Oral Cavity - Teeth#Mandibular Osteomyelitis|lumpy jaw]] and in [[Bones - inflammatory#Osteomyelitis|osteomyelitis]], may extend to surrounding [[Muscles - inflammatory#Actinomycosis bovis|muscles]]
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| − | *''Actinomyces pyogenes'' in [[Bones - inflammatory#Osteomyelitis|osteomyelitis]]
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| − | *In [[Pleural cavity and membranes - inflammatory#Pyothorax (Thoracic empyema)|pyothorax]]
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| − | *Isolated from closed cases of [[Bursae and Tendons - inflammatory#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
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| − | ===Overview===
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| − | *Gram positive bacteria
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| − | *Grow slowly on media and produce branching filaments
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| − | *Opportunistic infections causing inflammatory responses and granulomatous reactions
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| − | *Animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''
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| − | ===''Actinomyces, Arcanobacterium'' and ''Actinobaculum'' species===
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| − | *Non-motile, non-spore-forming bacteria
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| − | *Anaerobic or facultative anaerobes
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| − | *Grow on enriched media; non-acid fast
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| − | *Colonise mucous membranes
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| − | *''Arcanobacterium pyogenes''
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| − | **Characteristics:
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| − | ***Formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
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| − | ***Small rod
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| − | ***Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis after 48 hours
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| − | ***Coryneform morphology, like Chinese characters; may be curved with slightly swollen ends
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| − | ***Found in nasopharyngeal mucosa and genital tract of cattle, sheep, pigs
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| − | **Pathogenicity''
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| − | ***Opportunistic infections following injury or viral/mycoplasma infection in ruminants and pigs
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| − | ***Extracellular toxins including haemolysin, proteases, DNase and neurominidase
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| − | ***Haemolytic toxin, pyolysin, member of the thiol-activated cytolysins (pore-forming toxins); possibly cytotoxic to phagocytic cells
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| − | **Clinical infections:
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| − | ***Suppurative infections
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| − | ***Abscesses especially in liver
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| − | ***Pyometra
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| − | ***Summer mastitis
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| − | ***Ovine foot disease
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| − | ***Umbilical infections
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| − | ***Pneumonia
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| − | *''Actinomyces''
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| − | *Usually long and filamentous branching Gram positive rods
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| − | **''Actinomyces bovis'' found naturally in oral cavity of cattle; prefers anaerobic conditions but not strict anaerobe; penetrates injured tissues to cause granulomatous lesions of soft tissues and bone, causing lumpy jaw; organisms found in sulphur granules
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| − | **''Actinomyces viscosus'' commensal of oral cavity of dogs and humans; causes localised abscesses of skin or granulomatous lesions in thorax which may spread to abdomen causing pyothorax; rods contained in soft grey granules which release the organism when squashed
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| − | *''Actinbaculum suis'' in preputial mucosa of boars
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| − | *''Actinobaculum'' have a coryneform morphology
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| − | ''Nocardia''
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| − | *Aerobic short branching rods
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| − | *Cell wall contains mycolic acids (hence slightly acid fast)
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| − | *''Nocardia asteroides'' found in soil
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| − | *Causes granulomatous lesions in animals
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| − | *Survives and multiplies in macrophages
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| − | *Chronic, progressive disease
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| − | *Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
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