Difference between revisions of "Actinobacillus species"

From WikiVet English
Jump to navigation Jump to search
(Redirected page to Category:Actinobacillus species)
 
(21 intermediate revisions by 4 users not shown)
Line 1: Line 1:
<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
+
#REDIRECT[[:Category:Actinobacillus species]]
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
 
 
* Cause [[Peritoneal cavity - inflammatory#In horses|peritonitis in horses]]
 
 
 
===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]]
 
 
 
 
 
===''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
 
*[[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
 
*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
 
*''A. equuli'' in [[Joints - inflammatory#In Horses|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 [[Bacterial infections#Actinobacillus pleuropneumoniae|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
 

Latest revision as of 11:12, 10 May 2010