Actinobacillus Flashcards
(38 cards)
What kind of bacteria are Actinobacillus? How does it grow in TSI media? MacConkey?
small Gram-negative coccobacillus +/- filaments
weak fermentaters without gas —> orange
some can grow —> small, red colonies
What are 2 characteristics of Actinobacillus colonies on blood agar? Where are they typically found?
- colonies may be sticky
- some are β-hemolytic
obligate parasite of mucosal surfaces
What are the 4 major species of Actinobacillus and their hosts?
- A. lingnieresii - cattle, sheep, pigs
- A. pleuropneumoniae - pigs
- A. suis - pigs
- A. equuli subsp equuli - horses and pigs
- subsp haemolyticus - horses
In what animals does Actinobacillus pleuropneumoniae cause disease? What are the 2 biovars?
absolutely specific for pigs
BIOVAR 1 - requires V (NAD) factor and chocolate agar
BIOVAR 2 - doesn’t require V (NAD) factor
How does Actinobacillus pleuropneumoniae grow on blood agar? What serotypes are most common in US?
hemolytic
1, 5, 7
What is Actinobacillus pleuropneumoniae the causative agent of? What are 3 symptoms? When is transmission common?
swine pleuropneumonia
1. fibrinous pleuritis and pneumonia
2. hemorrhagic and necrotic lesions
3. subclinical to acute infection
chronic infections and carriers commonly spread disease to nonimmune herds
What are the 5 major clinical signs of swine pleuropneumonia? What tends to happen in pigs that recover?
- trembling
- anorexia
- dyspnea
- fever
- hemorrhage from nose and mouth
may continue to carry bacteria and be a source of new infections
What are 4 virulence factors of Actinobacillus pleuropneumoniae?
- capsule (serotypes)
- lipopolysaccharides (endotoxin)
- 4 RTX exotoxins (lytic for red and/or white blood cells)
- adhesions
What is responsible for hemorrhagic and necrotic lesions in Actinobacillus pneumoniae infection?
RTX toxins
Why dose Actinobacillus pleuropneumonia tend to have high virulence? What are some compromising factors?
not all produce the same exotoxins
- stress
- previous infection
- overcrowding
How can Actinobacillus pleuropneumoniae infection be controlled?
management - use closed herds and separate animals at different production stages
How is immunity to Actinobacillus pleuropneumoniae acquired? What tends to enhance opsonization and clearance?
provided by NEUTRALIZING antibodies to RTX (repeats in toxins) toxins
antibodies to capsule and somatic antigens —> can make infection worse by causing macrophages to phagocytize bacteria without exotoxin neutralization
Why don’t bacterins work well to develop immunity to Actinobacillus pleuropneumoniae? What is the best course?
cannot induce neutralizing antibodies to labile exotoxins
live attenuated vaccines - induce neutralizing antibodies to toxins
How do the 2 subspecies of Actinobacillus equuli compare?
EQUULI: resides primarily in tonsils and intestinal/reproductive tracts of horses and pigs, grows on MacConkey agar, nonhemolytic, contains RTX toxin
HAEMOLYTICUS: infects horses primarily in the respiratory tract, hemolytic, contains RTX toxin, less common
What is the causative agent of Sleepy Foal Disease? When is it typically obtained? What happens when co-infection occurs?
Actinobacillus equuli subsp. equuli
in utero or during birth - foal bacteremia
(Strongylus vulgaris in cranial mesenteric artery and its branches) - aneurysms
What are 4 common symptoms of Sleepy Foal Disease?
- bacteremia/septicemia
- enteritis (commonly only presentation in acute cases)
- abscesses and lesion present i kidneys and joints in less acute infections
- facial cellulitis
How does Actinobacillus equuli subsp. equuli affect pigs?
- death in sows
- pyrexia, arthritis, and mortality in piglets
What animals are primarily affected by Actinobacillus equuli subsp. haemolyticus? What does this cause? How is it transmitted to other species
adult horses - abortion, stillborn fetus, metritis, mastitis, meningitis, respiratory disease*, wound infections, bacteremia, arthritis, endocarditis, inflammed rounds
wounds following horse bites
What are the 3 major virulence factors of Actinobacillus equuli?
- LPS endotoxin
- adherence factors
- one RTX toxin (weak)
What are 5 compromising factors to Actinobacillus equuli nfection?
- mare carrying A. equuli in genital tract prior to delivery (screen and treat before delivery)
- stress (overtraining)
- infection
- climate/weather
- parasitism (S. vulgaris)
What is the best way to prevent Actinobacillus equuli infection?
- greater attention to sanitation in birthing environment
- maternal antibodies in colostrum
- prebreeding culture screening
In what animals do Actinobacillus lignieresii cause disease? Where is it commonly found? What does it require for initial isolation?
predominately in cattle and sheep, but may rarely cause infection in humans
commensal of oral cavity
serum/blood + CO2
What is Actinobacillus lignieresii the causative agent of? What does this cause?
“wooden tongue” or Actinobacillosis
tumor-like (granuloma) lesions of the tongue and oral cavity that may ulcerate, commonly following trauma where the bacteria is able to spread to internal organs and to skin
What happens when Actinobacillus lignieresii infection becomes chronic?
form granules similar to those caused by Actinomyces bovis, but smaller
