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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''
===''Actinomyces, Arcanobacterium'' and ''Actinobaculum'' species===
===''Actinomyces, Arcanobacterium'' and ''Actinobaculum'' species===
*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
*''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
*''Actinbaculum suis'' in preputial mucosa of boars
*''Actinobaculum'' have a coryneform morphology
''Nocardia''
*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)