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*''Arcanobacterium pyogenes'' formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
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*Opportunistic infections causing inflammatory responses and granulomatous reactions
*Opportunistic infections causing inflammatory responses and granulomatous reactions
*Animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''
*Animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''
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===''Actinomyces, Arcanobacterium'' and ''Actinobaculum'' species===
===''Actinomyces, Arcanobacterium'' and ''Actinobaculum'' species===
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*Non-motile, non-spore-forming bacteria
*Non-motile, non-spore-forming bacteria
*Anaerobic or facultative anaerobes
*Anaerobic or facultative anaerobes
−*Grow on enriched media
+*Grow on enriched media; non-acid fast
−*Colonise mucous membranes
*Colonise mucous membranes
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+*''Arcanobacterium pyogenes''
+**Characteristics:
+***Formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
+***Small rod
+***Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis 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
+**Pathogenicity''
+***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
+**Clinical infections:
+***Suppurative infections
+***Abscesses especially in liver
+***Pyometra
+***Summer mastitis
+***Ovine foot disease
+***Umbilical infections
+***Pneumonia
+*''Actinomyces''
+*Usually long and filamentous branching Gram positive rods
+**''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
+**''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
+*''Actinobaculum'' have a coryneform morphology
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+''Nocardia''
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+*Aerobic short branching rods
+*Cell wall contains mycolic acids (hence slightly acid fast)
+*''Nocardia asteroides'' found in soil
+*Causes granulomatous lesions in animals
+*Survives and multiplies in macrophages
+*Chronic, progressive disease
+*Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)