Corynebacterium species
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BACK TO BACTERIA
- C. pyogenes in arthritis of sheep post-dipping joint infection and arthritis in pigs and arthritis in cattle
- Corynebacterium pseudotuberculosis may cause myositis
- Corynebacterium pseudotuberculosis in deep pyoderma
Overview
- Common inhabitants of skin and mucous membranes of animals
- Opportunistic infections
- Cause pyogenic infections
- Most species host specific
Characteristics
- Small, tough, Gram positive rods
- Pleomorphic
- Cluster together to resemble Chinese characters - coryneform morphology
- Known as diphtheroids
- Catalase positive, oxidase negative
- Facultative anaerobes
- Require enriched media for growth
- Non-motile
Pathogenesis and pathogenicity
- Pyogenic causing
Clinical infections
- Infection follows tissue trauma
- Suppurative lesions
- C. pseudotuberculosis casues caseous lymphadenitis in sheep
- Carried on skin of sheep
- Produces a phospholipase toxin
- Infection through shearing wounds
- Facultative intracellular pathogen inside macrophages
- Ulcerative lymphangitis in horses
Diagnosis
- Colony characteristics:
- C. bovis: lipophilic bacterium; small, white, dry, non-haemolytic colonies on plates inoculated with bovine milk
- C. kutscheri: white colonies; occasionally haemolytic
- C. pseudotuberculosis: small, white coloniess surrounded by narrow zone of complete haemolysis; colonies become dry and cream-coloured
- C. renale: small, non-haemolytic colonies after 24 hours; pigment produced after 48 hours
- Biochemical reactions:
- Certain strains of C. pseudotuberculosis reduce nitrates
- All pathogenic strains except C. bovis produce urease
- Enhancement of haemolysis produced by C. pseudotuberculosis when inoculated across a streak of Rhodococcus equi