Difference between revisions of "Category:Actinobacillus species"

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

Actinobacillus pleuropneumoniae

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