Actinobacillus

• Actinobacillus

  • Gram negative, medium sized rods or cocobacilli
  • Non motile, non spore forming, non acid fast
  • Ferment carbohydrate w/o the production of gas
  • Urease and oxidase positive (most species)
  • A surface slime is present in the three major species and may be related to the stickiness of their colonies in agar. (A. lignieresii, A. equuli, A. suis)
  • Requires V factors (NAD) for its growth and improved by 5-10% co2 (capnophilic - Co2 loving)
  • Morse code appearance Virulence Factor
• LPS


  Potent endotoxin
• Surface slime


  Heat labile antigen (A. suis, A. equuli, A. lignieresii)
• RTX membrane active toxin


  Hemolysis can kill macrophages and neutrophils at high concentrations. Can stimulate an oxidative burst at lower concentrations
• Pili


  Specific adherence to alveolar epithelia and the cilia of terminal bronchioles
• Sources/Reservoir of Actinobacillus

  • Commensals on the mucous membrane of their hosts, particularly in the: upper respiratory tract and oral cavity
  • Surface cultures have low viability and die in 5-7 days
• Direct Microscopy

  Club colonies (crushed granules from pus or exudates)
• Chocolate agar


  Containing V factor
• CAMP Test

  Satellite growth on staphylococcal streak and improved by 5-10% CO incubated at 37°C for 24-72 hours
• Actinobacillus lignieresii


  • Small, glistening colonies develop in 24 hrs
  • Sticky (viscid) on primary isolation but lose this characteristic on subculture
  • Non-hemolytic, and develop to about 2mm in diameter in 48 hrs
  • Grow well on MCC (pinkish - late lactose-fermenter)
• Actinobacillus equuli


  • Hemolytic, sticky (remains even when subcultured)
  • Lactose-fermenter on MCC
• Actinobacillus suis


  • Hemolytic with colonies similar to A. lignieresii but more sticky
• Actinobacillus pleuropneumoniae


  • Small (1mm) colonies surrounded by a zone of B-hemolysis
  • Does not grow on MCC
• Actinobacillus lignieresii - Wooden tongue/Timber tongue

  Host

  -Cattle and Sheep

  Transmission

  -Entry of pathogen via erosions and lacerations in the buccal mucosa and skin caused by grazing rough pasture or some other type of trauma

  Diagnosis and Clinical signs and Lesions

  -difficulty in eating, drooling of saliva, presence of hard tumorous mass in the substance of the tongue, granulomatous lesions involving skin, and underlying tissues, usually head, neck, and limbs
• Actinobacillus lignieresii - Wooden tongue/Timber tongue

  Treatment and Prevention

  -Animals discharging lesions should be isolated

  -Sodium Iodide parenterally or Potassium Iodide orally is effective TMPS, Penicillin + Streptomycin

  -Oral Isoniazid for 30 days (animals with refractory lesions)

  -Rough feed should be avoided
• Actinobacillus equuli - Sleepy Foal Disease

  Host

  -Newborn foals and Adult horses (abortion, septicemia, peritonitis)

  Transmission

  -From a carrier mare that infects the newborn as it passes through her birth canal on its way out

  Diagnosis and Clinical signs

  -affected foals are febrile and recumbent

  -death after 1 or 2 days

  -foals which recover may develop: polyarthritis, nephritis, enteritis, or pneumonia

  -Microscopy and Bacterial cultures

  Lesions

  -Petechial hemorrhages on serosal surfaces and enteritis Meningoencephalitis

  -Pinpoint suppurative foci in the kidneys

             
• Actinobacillus pleuropneumoniae - Pleuropneumonia

  Host

  -Pigs (all ages)

  Predisposing factors

  -Poor ventilation and sudden drops in ambient temp may predispose the animal,

  Concurrent infections

  -P. multocida and Mycoplasmas

  Transmission

  -Aerosol (from subclinical carrier pigs)

  -harbor the organisms in the respiratory tract and tonsillar tissues
• Actinobacillus pleuropneumoniae - Pleuropneumonia

  Diagnosis and Clinical signs

  -dyspnea, pyrexia, anorexia and disinclination to move, presence of blood- stained froth from the nose and mouth, many show cyanosis, pregnant sows may abort

  Lesions

  -Areas of consolidation and necrosis in the lungs along with fibrinous pleurisy

  -Microscopy and Bacterial cultures

  Morbidity Case fatality

  -30-50%

  Case fatality

  -50%

  Treatment and Prevention

  -Chemotherapy based on AST Vaccination

  -Farm management
• Actinobacillus seminist - Epididymitis

  Host

  -Young rams and male sheeps

  Transmission

  -Ascending opportunistic infection (present in the prepuce)

  Diagnosis and Clinical signs

  -abscess formation in the epididymis, purulent discharge through fistulae into the scrotal skin

  -Microscopy and Bacterial cultures
• Actinobacillus suis

  Host

  -Young pigs (3 months of age)

  Transmission

  -Endogenous infection (present in the URT of sows and piglets)

  Diagnosis and Clinical

  -signs fever, respiratory distress prostration, paddling of the forelimbs

  -Microscopy and Bacterial cultures

  Lesions

  -petechial hemorrhages in many organs interstitial pneumonia, pleuritis, meningoencephalitis, myocarditis arthritis

  Treatment and Prevention

  -Chemotherapy based on AST Disinfection of contaminated pens