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>
 +
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 +
 
 +
===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''===
 +
 
 +
*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
 +
**[[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
 +
**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 pleuropneumoniae''===
 +
 
 +
*Contagious porcine pleuropneumonia especially of pigs under 6 months
 +
*Endemic in UK
 +
*12 serotypes causing the same disease
 +
*Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
 +
*Pathogenesis and pathogenicity:
 +
**Virulent strains possess capsules which are antiphagocytic and immunogenic
 +
**Fimbriae allow the bacteria to attach to cells of the respiratory tract
 +
**Damaged neutrophils in the lungs produce lytic enzymes
 +
**The sustained inflammatory response causes tissue necrosis
 +
**Lungs consolidated and necrotic with fibrinous pleuisy at post mortem
 +
**Produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX)  cytolysin family
 +
**RTX toxins:
 +
***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
 +
***Toxins introduce pores into cell membranes
 +
*Clinical signs and epidemiology:
 +
**Acute disease in susceptible herds with high morbidity and mortality (up to 50%)
 +
**In acute outbreaks, pigs may be dyspnoeic, pyrexic or anorexic
 +
**Blood-stained froth surrounding nose and mouth
 +
**Cyanosis
 +
**Pregnant sows abort
 +
**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
 +
*Diagnosis:
 +
**Haemorrhagic consolidation close to the main bronchi and fibrinous pleuritis may be suggestive
 +
**Specimens are cultured on chocolate agar and blood agar in 5-10% carbon dioxide for 2-3 days
 +
**Small colonies surrounded by clear haemolysis
 +
**No growth on MacConkey agar
 +
**Positive CAMP reaction with [[Staphylococcus spp.|''Staphylococcus aureus'']]
 +
**Most strains are NAD-dependent (grow on Heated Blood agar)
 +
**Immunofluorescent- or PCR-based techniques
 +
**The bacteria on the palatine tonsil may remain undetected by serological tests and swabbing, and can therefore cause an outbreak in naive pigs
 +
*Treatment:
 +
**Antibiotics depending on the strain of bacteria
 +
**Prophylactic antibiotics for in-contact pigs
 +
*Control:
 +
**Killed and polyvalent bacterin vaccines as well as a subunit vaccine are available 
 +
**Improve ventilation, avoid chilling and overcrowding
 +
 
 +
 
 +
 
 +
===''Actinobacillus equuli''===
 +
 
 +
*Commensal of the equine intestinal and reproductive tract
 +
*Pathogenesis and clinical signs:
 +
**Foals infected ''in utero'' or or after birth via the umbilicus
 +
**Infection at birth causes severe enteritis and septicaemia within 24 hours, known as sleepy foal disease
 +
**Foals become pyrexic and recumbent
 +
**Death usually occurs within 1-2 days
 +
**In foals that survive neonatal infection the condition progresses to cause joint infections and purulent nephritis, enteritis or pneumonia
 +
**''A. equuli'' in [[Joints - inflammatory#In Horses|arthritis of horses]]
 +
**Abortion, septicaemia and [[Peritoneal cavity - inflammatory#In horses|peritonitis in horses]]
 +
*Diagnosis:
 +
**Specimens cultured on blood agar and MacConkey agar and incubated aerobically for 1-3 days
 +
**Sticky colonies with variable haemolysis on blood agar
 +
**Lactose-fermenting colonies on MacConkey agar
 +
*Treatment and control:
 +
**Antimicrobials ineffective unless early in course of disease
 +
**Blood trasfusion and administration of colostrum
 +
**Good hygiene
 +
**Consider prophylactic antibiotics for new-born foals
 +
**Bacteria susceptible to streptomycin, tetracyclines and ampicillin
 +
*In other animals:
 +
**Septicaemia in piglets
 +
**Arthritis and enteritis in pigs
 +
**Enteritis in calves
 +
**RTX group cytotoxin present
 +
 
 +
 
 +
===''Actinobacillus suis''===
 +
 
 +
*May be present in upper respiratory tract of sows
 +
*Pathogenicity and clinical signs:
 +
**Infection of piglets via aerosol or possibly skin abrasions
 +
**Fatal septicaemia in piglets 1-8 weeks old
 +
**Mortality up to 50% in some litters
 +
**Fever, respiratory distress, prostration and paddling of forelimbs seen in piglets
 +
**Petechial and ecchymotic haemorrhages in many organs
 +
**Interstitial pneumonia, pleuritis, meningoencephalitis, myocarditis and arthritis
 +
**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
 +
*Diagnosis:
 +
**Specimens cultured on blood agar and MacConkey agar for 1-3 days
 +
**Sticky haemolytic colonies
 +
**Pink, lactose-fermenting colonies on MacConkey agar
 +
*Treatment and control:
 +
**Bacteria usually susceptible to ampicillin, carbenicillin, potentiated sulphonamides and tetracyclines
 +
**Disinfect contaminated pens
 +
*Other animals:
 +
**Septicaemia and pneumonia in foals
 +
**Pneumonia in pigs and horses
 +
 
 +
 
 +
===''Actinobacillus seminis''===
 +
 
 +
*Epididymitis in young rams (4-8 months)
 +
*Polyarthritis in lambs
 +
*Organism found in prepuce
 +
*Opportunistic infection causing abscesses in epididymides
 +
*May be purulent discharge onto scrotal skin
 +
*Specimens cultured on blood agar and incubated aerobically for 1-3 days produce pin-point haemolytic colonies which are catalase-positive; no growth on MacConkey agar
 +
 
 +
 
 +
===''Actinobacillus actinomycetemcomitans''===
 +
 
 +
*Epididymitis in rams

Revision as of 12:06, 21 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 pleuropneumoniae

  • Contagious porcine pleuropneumonia especially of pigs under 6 months
  • Endemic in UK
  • 12 serotypes causing the same disease
  • Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
  • Pathogenesis and pathogenicity:
    • Virulent strains possess capsules which are antiphagocytic and immunogenic
    • Fimbriae allow the bacteria to attach to cells of the respiratory tract
    • Damaged neutrophils in the lungs produce lytic enzymes
    • The sustained inflammatory response causes tissue necrosis
    • Lungs consolidated and necrotic with fibrinous pleuisy at post mortem
    • Produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX) cytolysin family
    • RTX toxins:
      • 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
      • Toxins introduce pores into cell membranes
  • Clinical signs and epidemiology:
    • Acute disease in susceptible herds with high morbidity and mortality (up to 50%)
    • In acute outbreaks, pigs may be dyspnoeic, pyrexic or anorexic
    • Blood-stained froth surrounding nose and mouth
    • Cyanosis
    • Pregnant sows abort
    • 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
  • Diagnosis:
    • Haemorrhagic consolidation close to the main bronchi and fibrinous pleuritis may be suggestive
    • Specimens are cultured on chocolate agar and blood agar in 5-10% carbon dioxide for 2-3 days
    • Small colonies surrounded by clear haemolysis
    • No growth on MacConkey agar
    • Positive CAMP reaction with Staphylococcus aureus
    • Most strains are NAD-dependent (grow on Heated Blood agar)
    • Immunofluorescent- or PCR-based techniques
    • The bacteria on the palatine tonsil may remain undetected by serological tests and swabbing, and can therefore cause an outbreak in naive pigs
  • Treatment:
    • Antibiotics depending on the strain of bacteria
    • Prophylactic antibiotics for in-contact pigs
  • Control:
    • Killed and polyvalent bacterin vaccines as well as a subunit vaccine are available
    • Improve ventilation, avoid chilling and overcrowding


Actinobacillus equuli

  • Commensal of the equine intestinal and reproductive tract
  • Pathogenesis and clinical signs:
    • Foals infected in utero or or after birth via the umbilicus
    • Infection at birth causes severe enteritis and septicaemia within 24 hours, known as sleepy foal disease
    • Foals become pyrexic and recumbent
    • Death usually occurs within 1-2 days
    • In foals that survive neonatal infection the condition progresses to cause joint infections and purulent nephritis, enteritis or pneumonia
    • A. equuli in arthritis of horses
    • Abortion, septicaemia and peritonitis in horses
  • Diagnosis:
    • Specimens cultured on blood agar and MacConkey agar and incubated aerobically for 1-3 days
    • Sticky colonies with variable haemolysis on blood agar
    • Lactose-fermenting colonies on MacConkey agar
  • Treatment and control:
    • Antimicrobials ineffective unless early in course of disease
    • Blood trasfusion and administration of colostrum
    • Good hygiene
    • Consider prophylactic antibiotics for new-born foals
    • Bacteria susceptible to streptomycin, tetracyclines and ampicillin
  • In other animals:
    • Septicaemia in piglets
    • Arthritis and enteritis in pigs
    • Enteritis in calves
    • RTX group cytotoxin present


Actinobacillus suis

  • May be present in upper respiratory tract of sows
  • Pathogenicity and clinical signs:
    • Infection of piglets via aerosol or possibly skin abrasions
    • Fatal septicaemia in piglets 1-8 weeks old
    • Mortality up to 50% in some litters
    • Fever, respiratory distress, prostration and paddling of forelimbs seen in piglets
    • Petechial and ecchymotic haemorrhages in many organs
    • Interstitial pneumonia, pleuritis, meningoencephalitis, myocarditis and arthritis
    • 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
  • Diagnosis:
    • Specimens cultured on blood agar and MacConkey agar for 1-3 days
    • Sticky haemolytic colonies
    • Pink, lactose-fermenting colonies on MacConkey agar
  • Treatment and control:
    • Bacteria usually susceptible to ampicillin, carbenicillin, potentiated sulphonamides and tetracyclines
    • Disinfect contaminated pens
  • Other animals:
    • Septicaemia and pneumonia in foals
    • Pneumonia in pigs and horses


Actinobacillus seminis

  • Epididymitis in young rams (4-8 months)
  • Polyarthritis in lambs
  • Organism found in prepuce
  • Opportunistic infection causing abscesses in epididymides
  • May be purulent discharge onto scrotal skin
  • Specimens cultured on blood agar and incubated aerobically for 1-3 days produce pin-point haemolytic colonies which are catalase-positive; no growth on MacConkey agar


Actinobacillus actinomycetemcomitans

  • Epididymitis in rams
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