Arcanobacter pyogenes

Formerly known as Actinomyces pyogenes and Corynebacterium pyogenes
Small facultatively anaerobic rod
Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis after 48 hours
Produces hazy haemolysis after 24 hours; pin-point colonies after 48 hours
Coryneform morphology, like Chinese characters; may be curved with slightly swollen ends
Found in nasopharyngeal mucosa and genital tract of cattle, sheep, pigs

Opportunistic infections following injury or viral/mycoplasma infection in ruminants and pigs
Extracellular toxins including haemolysin, proteases, DNase and neurominidase
Haemolytic toxin, pyolysin, member of the thiol-activated cytolysins (pore-forming toxins); possibly cytotoxic to phagocytic cells; dermonecrotising activity

Suppurative infections
Abscesses especially in liver
Lymphadenitis, osteomyelitis, peritonitis and neural abscessation
Pyometra
Endometritis
Summer mastitis
Ovine foot disease
Arthritis of sheep post-dipping; arthritis in pigs and arthritis in cattle
Umbilical infections
Acute exudative pneumonia and contributes to Enzootic pneumonia of calves
May cause myositis
Unclassified Actinomyces species isolated from closed cases of Poll Evil and Fistulous Withers

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