Difference between revisions of "Actinomycetes"

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#REDIRECT[[:Category:Actinomycetes]]
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|linkpage =Bacteria
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|linktext =BACTERIA
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<br>
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 +
===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, [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]], peritonitis and neural abscessation
 +
**Pyometra
 +
**Endometritis
 +
**Summer mastitis
 +
**Ovine foot disease
 +
**[[Joints Inflammatory - Pathology#In Sheep|Arthritis]] of sheep post-dipping; [[Joints Inflammatory - Pathology#In Pigs|arthritis in pigs]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]]
 +
**Umbilical infections
 +
**[[Respiratory Bacterial Infections - Pathology#Acute exudative pneumonia|Acute exudative pneumonia]] and contributes to [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]
 +
**May cause [[Muscles Inflammatory - Pathology#Abscesses|myositis]]
 +
**Unclassified ''Actinomyces'' species isolated from closed cases of [[Bursae and Tendons Inflammatory - Pathology#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
 +
*Treatment:
 +
**Penicillin or broad spectrum antibiotics
 +
 
 +
===''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
 +
***Entry of organism into tissues following trauma to the mucosa from rough feed or tooth eruption
 +
***Causes [[General Pathology - Chronic Inflammation#Granulomatous Inflammation|granulomatous inflammation]] of soft tissues and bone, causing [[Teeth - Pathology#Mandibular Osteomyelitis|lumpy jaw]]
 +
***Usually invades mandible to cause [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]] and may extend to surrounding [[Muscles Inflammatory - Pathology#Actinomycosis bovis|muscles]]
 +
***The lesions begins as a painless swelling of the affected bone
 +
***Swelling becomes more painful and enlarges over a number of weeks, gaining fistulous tracts which discharge pus
 +
***Organisms found in yellow sulphur granules
 +
***Club colony formation
 +
***Colonies adhere to agar media and are non-haemoltic
 +
***Surgical treatment possible when lesions are small
 +
***Prolonged parenteral penicillin treatment may be beneficial early in the disease
 +
**''Actinomyces viscosus''
 +
***Commensal of oral cavity of dogs and humans
 +
***Canine actinomycosis
 +
***Causes localised subcutaneous pyogranulomatous lesions and fibrovascular proliferation of peritoneal ([[Peritoneal Cavity Inflammatory - Pathology#In dogs|peritonitis]]) and pleural surfaces in dogs
 +
***Leads to [[Pleural Cavity & Membranes Inflammatory - Pathology#Pyothorax (Thoracic empyema)|pyothorax]]
 +
***Respiratory distress
 +
***[[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|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 [[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|cutaneous]] and visceral abscessation, pleuritis, peritonitis and arthritis in dogs
 +
 
 +
 
 +
===''Actinobaculum suis''===
 +
*Found in preputial mucosa of healthy boars
 +
*Anaerobic
 +
*Coryneform morphology
 +
*Produces urease
 +
*3mm diameter colonies with shiny raised centre and dull edge
 +
*Disease transmitted at coitus
 +
*Sows develop disease within 3-4 weeks of mating
 +
*Produces lesions in urinary tract of sows
 +
*Cystitis and pyelonephritis in sows
 +
*Anoreixa, arching of back, dysuria and haematuria
 +
*May be fatal
 +
 
 +
===''Nocardia''===
 +
 
 +
*Facultative intracellular bacterium
 +
*Aerobic short branching rods
 +
*Non-motile
 +
*Spores from aerial filaments when cultured
 +
*Grow on Sabouraud dextrose agar
 +
*Cell wall contains mycolic acids (hence slightly acid fast)
 +
*''Nocardia asteroides''
 +
**Found in soil and decaying vegetation - saprophytic
 +
**Opportunistic infection of immunocompromised animals
 +
**Infection via inhalation, wounds or teat canal; also ingestion
 +
**Causes granulomatous lesions in animals
 +
**Canine nocardiosis:  
 +
***Thoracic, [[Bacterial skin infections - Pathology#bacterial granulomatous dermatitis|cutaneous]] and disseminated forms
 +
***Cutaneous pyogranulomas: ulcers or granulomatous swellings with discharging fistulae
 +
***[[Peritoneal Cavity Inflammatory - Pathology#In dogs|peritonitis]]
 +
***[[Respiratory Bacterial Infections - Pathology#Nocardiosis|pleuritis]] and pyothorax with fever, anorexia and respiratory distress
 +
***Disseminated lesions
 +
***Treat with appropriate systemic antibiotics for 6 weeks
 +
**Cattle: chronic mastitis; abortion
 +
**Pigs: abortion
 +
**Sheep, goats, horses: wound infections; mastitis; pneumonia
 +
**Survives and multiplies in macrophages
 +
**Superoxide dismutase and catalase as well as a thick peptidoglycan wall prevent activity of phagocytes
 +
**Chronic, progressive disease
 +
**Positive modified Ziehl-Neelson
 +
**Culture on blood agar and incubate under aerobic conditions at 37 degrees centigrade for 10 days
 +
**White, powdery colonies, adherent to the agar appear after 5 days
 +
**Subculture onto Sabouraud dextrose agar yields wrinkled, orange colonies
 +
**Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
 +
**Cell-mediated immunity required
 +
*''Nocardia farcinica'' causes bovine farcy, a chronic infection of superficial lymphatic vessels and lymph nodes
 +
 
 +
===''Dermatophilus congolensis''===
 +
 
 +
*Filamentous, branching actinomycete
 +
*Aerobic
 +
*Produces motile zoospores
 +
*No growth on Sabouraud dextrose agar
 +
*Dermatophilosis most prevalent in tropical and subtropical regions
 +
*Organisms found in scabs and in foci in skin of carrier animals
 +
*Dormant zoospores become activated when moisture and temperature levels favourable
 +
*Zoospores may survive 3 years in scabs
 +
*'''Pathogenicity''':
 +
**Does not usually invade healthy skin
 +
**Entrance after trauma or persistent wetting
 +
**Activated zoospores produce germ tubes which develop into filaments which invade the epidermis
 +
**Invasion causes an accute inflammatory response with many neutrophils
 +
**Microabscesses are formed in the skin
 +
**Raised crusts develop in the affected regions
 +
*[[Bacterial skin infections - Pathology#Dermatophilosis|'''Pathology''']]
 +
*'''Diagnosis''':
 +
**Giemsa-stained smears from scabs reveal branching filaments containing zoospores
 +
**Immunofluorescence
 +
**Scab material can be cultured on blood agar at 37 degrees centigrade, 2.5-10% carbon dioxide for 5 days
 +
**Zoospores can be cultured
 +
**After incubation, colonies are yellow and haemolytic (after 48 hours); they later become rough and yellow, and gain a mucoid appearance
 +
**No growth on Sabouraud dectrose agar
 +
*'''Clinical infections''':
 +
**Infection usually confined to epidermis
 +
**Dermatophilosis
 +
**Disease most prevalent in young animals
 +
**Damage to the skin predisposes to infection; blood-sucking insects also thought to be involved in transmission
 +
**Lesions after heavy rainfall predominantly affect dorsum of farm animals
 +
**Papules, serous, exudative matting of hair, raised crusty scabs
 +
**Scab formation more prominent in sheep and cattle than in horses
 +
**Lesions may resolve within weeks if dry weather, or may progress
 +
*'''Treatment''':
 +
**Parenteral antibiotics e.g oxytetracycline, pr penicillin-streptomycin combinations
 +
 
 +
 
 +
*''Micropolyspora faeni and Thermactinomyces vulgaris'' in [[Bronchi and Bronchioles Inflammatory - Pathology#Extrinsic Allergic Bronchio-alveolitis|Bovine Farmers Lung]]
 +
*''Thermactinomyces vulgaris'' may cause [[Bronchi and Bronchioles Inflammatory - Pathology#Chronic obstructive pulmonary disease (COPD)|COPD]]

Revision as of 11:10, 29 December 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.


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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:
  • Treatment:
    • Penicillin or broad spectrum antibiotics

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
      • Entry of organism into tissues following trauma to the mucosa from rough feed or tooth eruption
      • Causes granulomatous inflammation of soft tissues and bone, causing lumpy jaw
      • Usually invades mandible to cause osteomyelitis and may extend to surrounding muscles
      • The lesions begins as a painless swelling of the affected bone
      • Swelling becomes more painful and enlarges over a number of weeks, gaining fistulous tracts which discharge pus
      • Organisms found in yellow sulphur granules
      • Club colony formation
      • Colonies adhere to agar media and are non-haemoltic
      • Surgical treatment possible when lesions are small
      • Prolonged parenteral penicillin treatment may be beneficial early in the disease
    • Actinomyces viscosus
      • Commensal of oral cavity of dogs and humans
      • Canine actinomycosis
      • Causes localised subcutaneous pyogranulomatous lesions and fibrovascular proliferation of peritoneal (peritonitis) 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 healthy boars
  • Anaerobic
  • Coryneform morphology
  • Produces urease
  • 3mm diameter colonies with shiny raised centre and dull edge
  • Disease transmitted at coitus
  • Sows develop disease within 3-4 weeks of mating
  • Produces lesions in urinary tract of sows
  • Cystitis and pyelonephritis in sows
  • Anoreixa, arching of back, dysuria and haematuria
  • May be fatal

Nocardia

  • Facultative intracellular bacterium
  • Aerobic short branching rods
  • Non-motile
  • Spores from aerial filaments when cultured
  • Grow on Sabouraud dextrose agar
  • Cell wall contains mycolic acids (hence slightly acid fast)
  • Nocardia asteroides
    • Found in soil and decaying vegetation - saprophytic
    • Opportunistic infection of immunocompromised animals
    • Infection via inhalation, wounds or teat canal; also ingestion
    • Causes granulomatous lesions in animals
    • Canine nocardiosis:
      • Thoracic, cutaneous and disseminated forms
      • Cutaneous pyogranulomas: ulcers or granulomatous swellings with discharging fistulae
      • peritonitis
      • pleuritis and pyothorax with fever, anorexia and respiratory distress
      • Disseminated lesions
      • Treat with appropriate systemic antibiotics for 6 weeks
    • Cattle: chronic mastitis; abortion
    • Pigs: abortion
    • Sheep, goats, horses: wound infections; mastitis; pneumonia
    • Survives and multiplies in macrophages
    • Superoxide dismutase and catalase as well as a thick peptidoglycan wall prevent activity of phagocytes
    • Chronic, progressive disease
    • Positive modified Ziehl-Neelson
    • Culture on blood agar and incubate under aerobic conditions at 37 degrees centigrade for 10 days
    • White, powdery colonies, adherent to the agar appear after 5 days
    • Subculture onto Sabouraud dextrose agar yields wrinkled, orange colonies
    • Lesions difficult to treat due to resistance of organisms to many antimicrobials (e.g. penicillins)
    • Cell-mediated immunity required
  • Nocardia farcinica causes bovine farcy, a chronic infection of superficial lymphatic vessels and lymph nodes

Dermatophilus congolensis

  • Filamentous, branching actinomycete
  • Aerobic
  • Produces motile zoospores
  • No growth on Sabouraud dextrose agar
  • Dermatophilosis most prevalent in tropical and subtropical regions
  • Organisms found in scabs and in foci in skin of carrier animals
  • Dormant zoospores become activated when moisture and temperature levels favourable
  • Zoospores may survive 3 years in scabs
  • Pathogenicity:
    • Does not usually invade healthy skin
    • Entrance after trauma or persistent wetting
    • Activated zoospores produce germ tubes which develop into filaments which invade the epidermis
    • Invasion causes an accute inflammatory response with many neutrophils
    • Microabscesses are formed in the skin
    • Raised crusts develop in the affected regions
  • Pathology
  • Diagnosis:
    • Giemsa-stained smears from scabs reveal branching filaments containing zoospores
    • Immunofluorescence
    • Scab material can be cultured on blood agar at 37 degrees centigrade, 2.5-10% carbon dioxide for 5 days
    • Zoospores can be cultured
    • After incubation, colonies are yellow and haemolytic (after 48 hours); they later become rough and yellow, and gain a mucoid appearance
    • No growth on Sabouraud dectrose agar
  • Clinical infections:
    • Infection usually confined to epidermis
    • Dermatophilosis
    • Disease most prevalent in young animals
    • Damage to the skin predisposes to infection; blood-sucking insects also thought to be involved in transmission
    • Lesions after heavy rainfall predominantly affect dorsum of farm animals
    • Papules, serous, exudative matting of hair, raised crusty scabs
    • Scab formation more prominent in sheep and cattle than in horses
    • Lesions may resolve within weeks if dry weather, or may progress
  • Treatment:
    • Parenteral antibiotics e.g oxytetracycline, pr penicillin-streptomycin combinations


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