- Cause peritonitis in dogs and peritonitis in cattle and peritonitis in pigs
- Nocardia is involved in peritonitis and pleuritis in dogs
- Micropolyspora faeni and Thermactinomyces vulgaris in Bovine Farmers Lung
- Thermactinomyces vulgaris may cause COPD
- Actinomyces may cause granulomatous inflammation.
- E.g. Actinomyces bovis -the cause of lumpy jaw and in osteomyelitis, may extend to surrounding muscles
- Actinomyces pyogenes in osteomyelitis
- In pyothorax
- Isolated from closed cases of Poll Evil and Fistulous Withers
Overview
- Gram positive bacteria
- Grow slowly on media and produce branching filaments
- Opportunistic infections causing inflammatory responses and granulomatous reactions
- Animal pathogens include Actinomyces, Arcanobacterium, Actinobaculum, Nocardia and Dermatophilus
Actinomyces, Arcanobacterium and Actinobaculum species
- Non-motile, non-spore-forming bacteria
- Anaerobic or facultative anaerobes
- Grow on enriched media; non-acid fast
- Colonise mucous membranes
- Arcanobacterium pyogenes
- Characteristics:
- 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
- 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; dermonecrotising activity
- Clinical infections:
- Suppurative infections
- Abscesses especially in liver
- Pyometra
- Summer mastitis
- Ovine foot disease
- Umbilical infections
- Pneumonia
- Characteristics:
- Actinomyces
- Usually long and filamentous branching Gram positive rods
- Anaerobic or facultativlyy anaerobic and capnophilic
- Live in nasopharyngeal and oral mucosa
- Cause pyogranulomatous lesions
- 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 yellow sulphur granules
- Club colony formation
- Colonies adhere to agar media and are non-haemoltic
- 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
- Two types of colonies: large and smooth colonies with V, Y and T configurations or small and rough colonies with short branching filaments
- Actinomyces bovis
- Actinobaculum suis
- Found in preputial mucosa of boars
- Anaerobic
- Coryneform morphology
- Produces urease
- Produces lesions in urinary tract of sows
- 3mm diameter colonies with shiny raised centre and dull edge
Nocardia
- Aerobic short branching rods
- Non-motile
- Spores from aerial filaments
- Grow on Sabouraud dextrose agar
- Cell wall contains mycolic acids (hence slightly acid fast)
- Nocardia asteroides found in soil
- Causes granulomatous lesions in animals
- Survives and multiplies in macrophages
- Lesions in thoracic cavity, skin and other tissues
- Chronic, progressive disease
- Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
Dermatophilus congolensis
- Aerobic
- Motile zoospores
- No growth on Sabouraud dextrose agar
- Found in scabs and in foci on skin of carrier animals