Difference between revisions of "Actinomycetes"

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#REDIRECT[[:Category:Actinomycetes]]
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<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
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<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
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*Cause [[Peritoneal cavity - inflammatory#In dogs|peritonitis in dogs]] and [[Peritoneal cavity - inflammatory#In cattle|peritonitis in cattle]] and [[Peritoneal cavity - inflammatory#In pigs|peritonitis in pigs]]
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*''Micropolyspora faeni and Thermactinomyces vulgaris'' in [[Bronchi and bronchioles - inflammatory#Extrinsic Allergic Bronchio-alveolitis|Bovine Farmers Lung]]
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*''Thermactinomyces vulgaris'' may cause [[Bronchi and bronchioles - inflammatory#Chronic obstructive pulmonary disease (COPD)|COPD]]
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===Overview===
 +
 
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*Gram positive bacteria
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*Grow slowly on media and produce branching filaments
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*Opportunistic infections causing inflammatory responses and granulomatous reactions
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*Animal pathogens include ''Actinomyces, Arcanobacterium, Actinobaculum, Nocardia'' and ''Dermatophilus''
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 +
 
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===''Arcanobacterium, Actinomyces'' and ''Actinobaculum'' species===
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*Non-motile, non-spore-forming bacteria
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*Anaerobic or facultative anaerobes
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*Grow on enriched media; non-acid fast
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*Colonise mucous membranes
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*Modified Ziehl-Neelson negative
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===''Arcanobacterium pyogenes''===
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*Characteristics:
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**Formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
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**Small facultatively anaerobic rod
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**Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis after 48 hours
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**Produces hazy haemolysis after 24 hours; pin-point colonies after 48 hours
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**Coryneform morphology, like Chinese characters; may be curved with slightly swollen ends
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**Found in nasopharyngeal mucosa and genital tract of cattle, sheep, pigs
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*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
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*Clinical infections:
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**Suppurative infections
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**Abscesses especially in liver
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**Lymphadenitis, [[Bones - inflammatory#Osteomyelitis|osteomyelitis]], peritonitis and neural abscessation
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**Pyometra
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**Endometritis
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**Summer mastitis
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**Ovine foot disease
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**Arthritis
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**Umbilical infections
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**Suppurative pneumonia
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*Treatment:
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**Penicillin or broad spectrum antibiotics
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**Unclassified ''Actinomyces'' species isolated from closed cases of [[Bursae and Tendons - inflammatory#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
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===''Actinomyces''===
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*Usually long filamentous branching Gram positive rods
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*Anaerobic or facultativlyy anaerobic and capnophilic
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*Live in nasopharyngeal and oral mucosa
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*Cause pyogranulomatous lesions
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**''Actinomyces bovis''
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***Found naturally in oral cavity of cattle
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***Prefers anaerobic conditions but not strict anaerobe
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***Penetrates injured tissues to cause [[General Pathology - Chronic Inflammation#Granulomatous Inflammation|granulomatous inflammation]] lesions of soft tissues and bone, causing [[Oral Cavity - Teeth#Mandibular Osteomyelitis|lumpy jaw]]
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***Usually invades mandible to cause [[Bones - inflammatory#Osteomyelitis|osteomyelitis]] and may extend to surrounding [[Muscles - inflammatory#Actinomycosis bovis|muscles]]
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***Organisms found in yellow sulphur granules
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***Club colony formation
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***Colonies adhere to agar media and are non-haemoltic
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**''Actinomyces viscosus''
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***Commensal of oral cavity of dogs and humans
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***Canine actinomycosis
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***Causes localised subcutaneous pyogranulomatous lesions and fibrovascular proliferation of peritoneal and pleural surfaces in dogs
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***Leads to [[Pleural cavity and membranes - inflammatory#Pyothorax (Thoracic empyema)|pyothorax]]
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***Respiratory distress
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***Cutaneous pustules in horses
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***Abortion in cattle
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***Rods contained in soft grey granules which release the organism when squashed
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***Two types of colonies: large and smooth colonies with V, Y and T configurations or small and rough colonies with short branching filaments
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***Grow in 10% carbon dioxide
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***Usually responds to penicillin
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**''Actinomyces hordeovulneris''
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***Organism found in seed heads of certain grasses
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***Colonies adhere to agar and are non-haemolytic
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***Filamentous, branching organisms
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***Cause cutaneous and visceral abscessation, pleuritis, peritonitis and arthritis in dogs
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 +
 
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===''Actinobaculum suis''===
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**Found in preputial mucosa of boars
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**Anaerobic
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**Coryneform morphology
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**Produces urease
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**3mm diameter colonies with shiny raised centre and dull edge
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**Produces lesions in urinary tract of sows
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**Cystitis and pyelonephritis in sows
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 +
 
 +
===''Nocardia''===
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*Aerobic short branching rods
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*Non-motile
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*Spores from aerial filaments
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*Grow on Sabouraud dextrose agar
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*Cell wall contains mycolic acids (hence slightly acid fast)
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*''Nocardia asteroides'' found in soil
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*Causes granulomatous lesions in animals
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*Involved in [[Peritoneal cavity - inflammatory#In dogs|peritonitis]] and [[Bacterial infections#Nocardiosis|pleuritis]] in dogs
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*Survives and multiplies in macrophages
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*Lesions in thoracic cavity, skin and other tissues
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*Chronic, progressive disease
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*Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
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===''Dermatophilus congolensis''===
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*Aerobic
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*Motile zoospores
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*No growth on Sabouraud dextrose agar
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*Found in scabs and in foci on skin of carrier animals

Revision as of 15:59, 17 February 2008

BACK TO INFECTIOUS AGENTS AND PARASITES
BACK TO BACTERIA



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


Arcanobacterium, Actinomyces and Actinobaculum species

  • Non-motile, non-spore-forming bacteria
  • Anaerobic or facultative anaerobes
  • Grow on enriched media; non-acid fast
  • Colonise mucous membranes
  • Modified Ziehl-Neelson negative


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
    • Lymphadenitis, osteomyelitis, peritonitis and neural abscessation
    • Pyometra
    • Endometritis
    • Summer mastitis
    • Ovine foot disease
    • Arthritis
    • Umbilical infections
    • Suppurative pneumonia
  • Treatment:


Actinomyces

  • Usually long 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 inflammation lesions of soft tissues and bone, causing lumpy jaw
      • Usually invades mandible to cause osteomyelitis and may extend to surrounding muscles
      • 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
      • Canine actinomycosis
      • Causes localised subcutaneous pyogranulomatous lesions and fibrovascular proliferation of peritoneal and pleural surfaces in dogs
      • Leads to pyothorax
      • Respiratory distress
      • Cutaneous pustules in horses
      • Abortion in cattle
      • 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
      • Grow in 10% carbon dioxide
      • Usually responds to penicillin
    • Actinomyces hordeovulneris
      • Organism found in seed heads of certain grasses
      • Colonies adhere to agar and are non-haemolytic
      • Filamentous, branching organisms
      • Cause cutaneous and visceral abscessation, pleuritis, peritonitis and arthritis in dogs


Actinobaculum suis

    • Found in preputial mucosa of boars
    • Anaerobic
    • Coryneform morphology
    • Produces urease
    • 3mm diameter colonies with shiny raised centre and dull edge
    • Produces lesions in urinary tract of sows
    • Cystitis and pyelonephritis in sows


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
  • Involved in peritonitis and pleuritis in dogs
  • 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
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