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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* ''A. pleuropneumoniae'' causes [[Bacterial infections#Actinobacillus pleuropneumoniae|pneumonia]] in pigs
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* Cause [[General Pathology - Chronic Inflammation#Granulomatous Inflammation|granulomatous inflammation]].
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** E.g. ''Actinobacillus lignieresii'' causes wooden tongue in cattle -> [[Muscles - inflammatory#Wooden tongue|myositis]]
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*''A. equuli'' in [[Joints - inflammatory#In Horses|arthritis of horses]]
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===Overview===
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*Mainly pathogens of farm animals
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*Commensals of mucosa of upper respiratory tract and oral cavity
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*Cannot survive long in the environment, therefore carrier animals are important in their transmission
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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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*Commensal in the mouth of sheep and cattle
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*Penetrates damaged mucosa to cause a granuloma, a condition known as Actinobacillosis
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*Enodogenous, sporadic and chronic infection
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*Lesions in the tongue, cheek, lips and sometimes in the lower gut and lungs from aspiration
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*Often spreads from the site of infection to lymphatics
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*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
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*Feeding is impaired, causing loss of condition
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*Recovery with antibiotics
 +
 
 +
 
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===''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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*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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===''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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*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
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*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 
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*Produce one or two RTX group cytolytic toxins
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*RTX toxins:
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**'Repeat in ToXin' - named because there are several peptide repeats within the molecules
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**Produced by various Gram-negative bacteria
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**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
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**ApxI is a strong haemolysin with cytolytic activity
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**ApxII is a weak haemolysin
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**ApxIII is a cytotoxin
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**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 13:12, 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


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

  • Commensal in the mouth of sheep and cattle
  • Penetrates damaged mucosa to cause a granuloma, a condition known as Actinobacillosis
  • Enodogenous, sporadic and chronic 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
  • 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
  • Recovery with antibiotics


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
  • 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
  • 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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