Difference between revisions of "Corynebacterium species"

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===Diagnosis===
 
===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''

Revision as of 12:05, 18 May 2008

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  • Corynebacterium pseudotuberculosis may cause myositis
  • Corynebacterium pseudotuberculosis in deep pyoderma

Overview

  • Common inhabitants of skin and mucous membranes of animals
  • 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


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