Difference between revisions of "Corynebacterium species"

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|linktext =BACTERIA
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<br>
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===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. 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
 +
 
 +
 
 +
===''Corynebacterium pseudotuberculosis''===
 +
 
 +
*Caseous lymphadenitis:
 +
**''C. pseudotuberculosis'' carried on skin of sheep
 +
**Non-nitrate-reducing biotype
 +
**Infection follows tissue trauma such as shearing wounds
 +
**Incubation period 3 months
 +
**Chronic suppurative infection of sheep, goats and occasionally cattle
 +
**Abscessation of superficial and internal lymph nodes if haemtogenous spread occurs
 +
**Caseous abscesses with green colour and onion ring appearance
 +
**Ill thrift and pneumonia may occur
 +
**Condemnation of carcasses and hides
 +
**Infection spread by pus from abscesses, and oculonasal secretions
 +
**Organism survives in environment for several months
 +
**Sandwich ELISA detects circulating antibodies to phospholipase toxin
 +
**Control: importation measures including screening; culling of infected sheep, stict hygiene; inactivated vaccine
 +
*Ulcerative lymphangitis:
 +
**Nitrate reducing biotype
 +
**Disease in horses and cattle
 +
**Infection through skin wounds
 +
**Lymphangitis of lower limbs or abscessation in pectoral region
 +
**Slow onset, usually becomes chronic
 +
**Affected lymphatic vessels swollen and firm with nodules
 +
**Oedema in affected limbs
 +
**Ulcerative nodules exude thick green pus
 +
**Lymphangitis and lymphadenitis in cattle with abscesses as well as coronary band lesions causing lameness
 +
**Antibiotic treatment and topical iodophore shampoo
 +
*May cause [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
 +
*Involved in [[Bacterial skin infections - Pathology#Deep pyoderma|deep pyoderma]]
 +
 
 +
 
 +
===''Corynebacterium renale''===
 +
 
 +
*''C. renale, C. pilosum, C. cystitidis''
 +
*Found in the vulva, vagina and prepuce of normal cattle
 +
*Bovine pyelonephritis
 +
**Stress of parturition and short urethra predisposes cows to urinary tract infection
 +
**Cystitis especially with ''C. cystitidis
 +
**Ascending infection from bladder through ureters causes pyelonephritis
 +
**Fever, anoexia, decreased milk production
 +
**Restlessness; kicking of abdomen indicate renal pain
 +
**Dysurea, arched back, bloody urine
 +
**Chronic infection causes extensive renal damage
 +
**Enlarged ureters and kidneys palpated per rectum
 +
**Culture from urine; protein and red blood cells in urine
 +
**Antibiotics e.g. penicillin for at least three weeks
 +
*Ulcerative balanoposthitis (pizzle rot):
 +
**Common in Merino sheep and Angora goats
 +
**Ulceration around prepucial orifice with brown crust, and occasionally on vulva of ewes
 +
**Bacteria hydrolyse urea to ammonia which causes mucosal irritation and ulceration
 +
**High urine urea level, from high protein intake may predispose to condition
 +
**High oestrogen levels in pastures also predisposes
 +
**Castration and heavy wool aroung the prepuce are risk factors
 +
 
 +
 
 +
===''Corynebacterium bovis''===
 +
 
 +
*Subclinical mastitis in cattle
 +
*Found in teat cistern
 +
*Causes mild neutrophil response in teat canal of healthy dairy cows and may protect against invasion from more pathogenic bacteria
 +
 
 +
 
 +
===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''

Revision as of 09:41, 25 September 2008

 This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing.


Infectious agents and parasitesWikiBugs Banner.png
BACTERIA



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. 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


Corynebacterium pseudotuberculosis

  • Caseous lymphadenitis:
    • C. pseudotuberculosis carried on skin of sheep
    • Non-nitrate-reducing biotype
    • Infection follows tissue trauma such as shearing wounds
    • Incubation period 3 months
    • Chronic suppurative infection of sheep, goats and occasionally cattle
    • Abscessation of superficial and internal lymph nodes if haemtogenous spread occurs
    • Caseous abscesses with green colour and onion ring appearance
    • Ill thrift and pneumonia may occur
    • Condemnation of carcasses and hides
    • Infection spread by pus from abscesses, and oculonasal secretions
    • Organism survives in environment for several months
    • Sandwich ELISA detects circulating antibodies to phospholipase toxin
    • Control: importation measures including screening; culling of infected sheep, stict hygiene; inactivated vaccine
  • Ulcerative lymphangitis:
    • Nitrate reducing biotype
    • Disease in horses and cattle
    • Infection through skin wounds
    • Lymphangitis of lower limbs or abscessation in pectoral region
    • Slow onset, usually becomes chronic
    • Affected lymphatic vessels swollen and firm with nodules
    • Oedema in affected limbs
    • Ulcerative nodules exude thick green pus
    • Lymphangitis and lymphadenitis in cattle with abscesses as well as coronary band lesions causing lameness
    • Antibiotic treatment and topical iodophore shampoo
  • May cause myositis
  • Involved in deep pyoderma


Corynebacterium renale

  • C. renale, C. pilosum, C. cystitidis
  • Found in the vulva, vagina and prepuce of normal cattle
  • Bovine pyelonephritis
    • Stress of parturition and short urethra predisposes cows to urinary tract infection
    • Cystitis especially with C. cystitidis
    • Ascending infection from bladder through ureters causes pyelonephritis
    • Fever, anoexia, decreased milk production
    • Restlessness; kicking of abdomen indicate renal pain
    • Dysurea, arched back, bloody urine
    • Chronic infection causes extensive renal damage
    • Enlarged ureters and kidneys palpated per rectum
    • Culture from urine; protein and red blood cells in urine
    • Antibiotics e.g. penicillin for at least three weeks
  • Ulcerative balanoposthitis (pizzle rot):
    • Common in Merino sheep and Angora goats
    • Ulceration around prepucial orifice with brown crust, and occasionally on vulva of ewes
    • Bacteria hydrolyse urea to ammonia which causes mucosal irritation and ulceration
    • High urine urea level, from high protein intake may predispose to condition
    • High oestrogen levels in pastures also predisposes
    • Castration and heavy wool aroung the prepuce are risk factors


Corynebacterium bovis

  • Subclinical mastitis in cattle
  • Found in teat cistern
  • Causes mild neutrophil response in teat canal of healthy dairy cows and may protect against invasion from more pathogenic bacteria


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
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