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===Characteristics===
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*Formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
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*Small facultatively anaerobic 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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*Produces hazy haemolysis after 24 hours; pin-point colonies 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; dermonecrotising activity
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===Clinical infections===
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*Suppurative infections
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*Abscesses especially in liver
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*Lymphadenitis, [[Bones - inflammatory#Osteomyelitis|osteomyelitis]], peritonitis and neural abscessation
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*Pyometra
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*Endometritis
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*Summer mastitis
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*Ovine foot disease
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*Arthritis
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*Umbilical infections
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*[[Bacterial infections#Acute exudative pneumonia|Acute exudative pneumonia]] and contributes to [[Bacterial infections#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]
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*May cause [[Muscles - inflammatory#Abscesses|myositis]]
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===Treatment===
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*Penicillin or broad spectrum antibiotics
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*Unclassified ''Actinomyces'' species isolated from closed cases of [[Bursae and Tendons - inflammatory#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
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