Difference between revisions of "Actinobacillus species"

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#REDIRECT[[:Category:Actinobacillus species]]
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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 horses|peritonitis in horses]]
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===Overview===
 +
 
 +
*Mainly pathogens of farm animals
 +
*Commensals of mucosa of upper respiratory tract and oral cavity
 +
*Cannot survive long in the environment, therefore carrier animals are important in their transmission
 +
*Cause [[General Pathology - Chronic Inflammation#Granulomatous Inflammation|granulomatous inflammation]]
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 +
 
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===''Actinobacillus'' characteristics===
 +
 
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*Small Gram negative coccobacilli
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*Oxidase negative
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*Do not grow on MacConkey
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*Non-motile
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*Facultative anaerobes which ferment carbohydrates to produce acid
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 +
 
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===''Actinobacillus lignieresii''===
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*Pathogenesis and pathogenicity:
 +
**Commensal in the mouth and intestinal tract of cattle and sheep
 +
**Penetrates damaged mucosa to cause chronic granulomatous inflammation of soft tissues, a condition known as Actinobacillosis
 +
**Enodogenous, sporadic infection
 +
**Lesions in the tongue, cheek, lips and sometimes in the lower gut and lungs from aspiration
 +
**Often spreads from the site of infection to lymphatics, and may cause pyogranulomatous lymphadenitis
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**[[Muscles - inflammatory#Wooden tongue|myositis]] and formation of fibrous tissue in the lesions lead to hardening of the tissue, hence the condition is known as 'wooden tongue' in cattle
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**In sheep abscesses with thick walls are produced
 +
**Feeding is impaired, causing loss of condition
 +
**Infection in the oesophageal groove can cause tympany and enlargement of the retropharyngeal lymph node, causing difficulty in swallowing and breathing
 +
**Cutaneous lesions in cattle and sheep
 +
**Contamination of the environment via ulcerating lesions
 +
*Diagnosis:
 +
**Induration of tongue
 +
**Tissue sections may demonstrate pyogranulomatous foci containing club colonies
 +
**Gram negative rods may be present in smears from exudates
 +
**Cultures on blood agar and MacConkey agar, incubated for 24-72 hours
 +
**Blood agar: small, sticky, non-haemolytic clonies
 +
**MacConkey agar: slow lactose fermentation
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*Treatment:
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**Sodium iodide parenterally, or potassium iodide orally
 +
**Potentiated sulphonamides or a penicillin/streptomycin combination
 +
**Rough feed should be avoided
 +
 
 +
 
 +
===''Actinobacillus equuli''===
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*Commensal of the equine intestinal mucosa
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*Infection at birth causes severe enteritis and septicaemia within 24 hours, known as sleepy foal disease
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*In foals that survive neonatal infection the condition progresses to cause joint infections and purulent nephritis
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*''A. equuli'' in [[Joints - inflammatory#In Horses|arthritis of horses]]
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*RTX group cytotoxin present
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===''Actinobacillus suis''===
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*Fatal septicaemia in pigs 1-8 weeks old
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*Causes abscesses in joints and lungs of older pigs
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*Carried in the nasopharynx of pigs and nose of horses
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*Carriage may confer immunity to the more severe pleuropneumonia
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 +
 
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===''Actinobacillus pleuropneumoniae''===
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*Contagious porcine pleuropneumonia
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*Endemic in UK
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*Most strains are NAD-dependent (grow on Heated Blood agar)
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*Positive CAMP reaction
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*12 serotypes causing the same disease
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*Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
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*Acute disease in susceptible herds with high morbidity and mortality
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*Causes [[Bacterial infections#Actinobacillus pleuropneumoniae|pneumonia]] in pigs
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*Carrier herds have some immunity, protecting from acute disease, where lesions are often subclinical, and deaths sporadic
 +
*Lung scarring and pleural adhesions in many recovered animals
 +
*Solid immunity develops in recovered animals to all serotypes
 +
*The disease is spread between herds by carrier pigs
 +
*The bacteria on the palatine tonsil are undetected by serologucal tests and swabbing, and can therefore cause an outbreak in naive pigs
 +
*Killed and bacterin vaccines are available 
 +
*Produce one or two RTX group cytolytic toxins
 +
*RTX toxins:
 +
**'Repeat in ToXin' - named because there are several peptide repeats within the molecules
 +
**Produced by various Gram-negative bacteria
 +
**Possess four contiguous genes, A, B, C and D
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**A is the structural gene; B and D are required for secretion; C allows post-translational activation of the gene product of A into a functional product
 +
**ApxI is a strong haemolysin with cytolytic activity
 +
**ApxII is a weak haemolysin
 +
**ApxIII is a cytotoxin
 +
**Different ''Actinobacillus pleuropneumonia'' serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III

Revision as of 13:41, 20 December 2007

BACK TO INFECTIOUS AGENTS AND PARASITES
BACK TO BACTERIA

Overview

  • Mainly pathogens of farm animals
  • Commensals of mucosa of upper respiratory tract and oral cavity
  • Cannot survive long in the environment, therefore carrier animals are important in their transmission
  • Cause granulomatous inflammation


Actinobacillus characteristics

  • Small Gram negative coccobacilli
  • Oxidase negative
  • Do not grow on MacConkey
  • Non-motile
  • Facultative anaerobes which ferment carbohydrates to produce acid


Actinobacillus lignieresii

  • Pathogenesis and pathogenicity:
    • Commensal in the mouth and intestinal tract of cattle and sheep
    • Penetrates damaged mucosa to cause chronic granulomatous inflammation of soft tissues, a condition known as Actinobacillosis
    • Enodogenous, sporadic infection
    • Lesions in the tongue, cheek, lips and sometimes in the lower gut and lungs from aspiration
    • Often spreads from the site of infection to lymphatics, and may cause pyogranulomatous lymphadenitis
    • myositis and formation of fibrous tissue in the lesions lead to hardening of the tissue, hence the condition is known as 'wooden tongue' in cattle
    • In sheep abscesses with thick walls are produced
    • Feeding is impaired, causing loss of condition
    • Infection in the oesophageal groove can cause tympany and enlargement of the retropharyngeal lymph node, causing difficulty in swallowing and breathing
    • Cutaneous lesions in cattle and sheep
    • Contamination of the environment via ulcerating lesions
  • Diagnosis:
    • Induration of tongue
    • Tissue sections may demonstrate pyogranulomatous foci containing club colonies
    • Gram negative rods may be present in smears from exudates
    • Cultures on blood agar and MacConkey agar, incubated for 24-72 hours
    • Blood agar: small, sticky, non-haemolytic clonies
    • MacConkey agar: slow lactose fermentation
  • Treatment:
    • Sodium iodide parenterally, or potassium iodide orally
    • Potentiated sulphonamides or a penicillin/streptomycin combination
    • Rough feed should be avoided


Actinobacillus equuli

  • Commensal of the equine intestinal mucosa
  • Infection at birth causes severe enteritis and septicaemia within 24 hours, known as sleepy foal disease
  • In foals that survive neonatal infection the condition progresses to cause joint infections and purulent nephritis
  • A. equuli in arthritis of horses
  • RTX group cytotoxin present


Actinobacillus suis

  • Fatal septicaemia in pigs 1-8 weeks old
  • Causes abscesses in joints and lungs of older pigs
  • Carried in the nasopharynx of pigs and nose of horses
  • Carriage may confer immunity to the more severe pleuropneumonia


Actinobacillus pleuropneumoniae

  • Contagious porcine pleuropneumonia
  • Endemic in UK
  • Most strains are NAD-dependent (grow on Heated Blood agar)
  • Positive CAMP reaction
  • 12 serotypes causing the same disease
  • Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
  • Acute disease in susceptible herds with high morbidity and mortality
  • Causes pneumonia in pigs
  • Carrier herds have some immunity, protecting from acute disease, where lesions are often subclinical, and deaths sporadic
  • Lung scarring and pleural adhesions in many recovered animals
  • Solid immunity develops in recovered animals to all serotypes
  • The disease is spread between herds by carrier pigs
  • The bacteria on the palatine tonsil are undetected by serologucal tests and swabbing, and can therefore cause an outbreak in naive pigs
  • Killed and bacterin vaccines are available
  • Produce one or two RTX group cytolytic toxins
  • RTX toxins:
    • 'Repeat in ToXin' - named because there are several peptide repeats within the molecules
    • Produced by various Gram-negative bacteria
    • Possess four contiguous genes, A, B, C and D
    • A is the structural gene; B and D are required for secretion; C allows post-translational activation of the gene product of A into a functional product
    • ApxI is a strong haemolysin with cytolytic activity
    • ApxII is a weak haemolysin
    • ApxIII is a cytotoxin
    • Different Actinobacillus pleuropneumonia serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III
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