Difference between revisions of "Corynebacterium species"

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<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
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#REDIRECT[[:Category:Corynebacterium species]]
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
 
 
 
 
*''C. pyogenes'' in [[Joints - inflammatory#In Sheep|arthritis]] of sheep post-dipping joint infection and [[Joints - inflammatory#In Pigs|arthritis in pigs]] and [[Joints - inflammatory#In Cattle|arthritis in cattle]]
 
 
 
*''Corynebacterium pseudotuberculosis'' may cause [[Muscles - inflammatory#Abscesses|myositis]]
 
*''Corynebacterium pseudotuberculosis'' in [[Bacterial skin infections#Deep pyoderma|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 suppurative infections except for ''C. bovis''
 
*''C. bovis'' causes mild neutrophil response in teat canal of healthy dairy cows and may protect from more pathogenic bacteria
 
*''C. pseudotuberculosis'':
 
**Facultative intracellular pathogen inside macrophages
 
**Cell wall lipid
 
**Produces a phospholipase toxin which hydolyses sphingomyelin in mammalian cell membranes
 
**Phospholipase may enhance survival and multiplication in host in early stages
 
*''C. renale''
 
**Urinary tract pathogens
 
**Produce urease and hydrolyse urea
 
**Possess fimbriae for attachment to urogenital mucosa
 
**Infection when immunity reduced or following tissue damage during parturition
 
 
 
 
 
===Clinical infections===
 
 
 
*Infection follows tissue trauma
 
*''C. pseudotuberculosis'' casues caseous lymphadenitis in sheep
 
*Carried on skin of sheep
 
 
 
*Infection through shearing wounds
 
 
 
*Ulcerative lymphangitis in horses
 
 
 
 
 
===Diagnosis===
 
 
 
*Samples include pus, exudate, affected tissues and urine
 
*Presence of coryneform organisms in smears
 
*Culture on blood agar, selective blood agar and MacConkey agar
 
*Do not grow on MacConkey
 
*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''
 

Latest revision as of 12:30, 12 May 2010