Unit 3: Actinobacillus Flashcards
On gram stain, what does the genus Actinobacillus look like?
small, gram-negative, pleomorphic coccabacilli
On MacConkey’s what do colonies of Actinobacillus look like?
they produce small colonies if they do grow
What does Actinobacillus lignieresii cause and in what species?
Cattle Wooden tongue - granulomatous, tumor-like infections, usually in the head and neck area
What is the best environment for Actinobacillus lignieresii to grow in?
with serum in the media and primary cultures grow much better with an atmosphere of 10% CO2 in air
What is the natural habitat of Actinobacillus lignieresii?
commensal of the buccal mucous membrane of cattle and sheep
How does Actinobacillus lignieresii infect cattle
enters deeper tissues via wounds in the buccal epithelium
What is the pathogenesis of an Actinobacillus lignieresii infection in cattle?
- Granulomatous abscesses form in any part of the body most frequently in the soft tissue of the lower jaw and neck 2. The abscesses eventually break through to the skin creating a deep ulcer that will not heal 3. If untreated, the ulcers tend to enlarge and additional ulcers may form 4. The organism may spread to internal organs, lung, and lymphoid tissue
What allows Actinobacillus lignieresii to form granules?
a glycocalyx or capsule that cements the organism together
What immune responses are important against Actinobacillus lignieresii infections?
humoral and cell mediated immune responses
True or False: Many cattle have antibody against Actinobacillus lignieresii.
True
How is infection caused by Actinobacillus lignieresii treated?
Debridement and local injections of aqueous iodine, streptomycin, tetracycline, and sulfas
What is the cause of shigellosis?
Actinobacillus equuli
What animals does shigellosis infect?
foals
In adults, what does Actinobacillus equuli cause?
verminous aneurysms
How does Actinobacillus equuli grow on culture?
it grows readily and abundantly on ordinary media Inconsistent growth on MacConkey’s (small colonies)
What do colonies of Actinobacillus equuli look like?
slimy and mucoid, non-hemolytic except for subspecies haemolytica
What is the natural habitat for Actinobacillus equuli?
the oral cavity and intestinal tract of normal horses
What is the general pathogenesis of Actinobacillus equuli infection?
It is an opportunist. Disease is sporadic and usually only occurs in debilitated or stressed horses. Foals can contract the infection as they pass through the birth canal of infected mares. There is some indication that in-utero transmission occurs. Whatever the source, the organism becomes septicemic in foals
What percentage of foals die of equulosis within 24 hours of birth and what lesion is associated with it?
1/3 - severe enteritis
What percentage of foals die of equulosis within 4 days of birth and what lesions are associated with it?
2/3 - severe purulent nephritis with multiple small abscesses throughout the kidney cortex. Leg joints are frequently affected
What is the pathogenesis of infection of Actinobacillus equuli in adult horses?
The organism may gain access to the blood when the larvae of Strongylus vulgaris migrates into the blood vessels from the intestine. Verminous aneurysms in the mesenteric arteries caused by migrating strongylus larvae are frequently infected with this organism. Infected horses often have a septicemia
Can horses develop immunity against Actinobacillus equuli?
no - there is not enough time to develop much of an immune response
Is there a vaccine for Actinobacillus equuli?
no - there is an experimental autogenous bacterin
How is Actinobacillus equuli infection treated?
Streptomycin, penicillin, but caution should be used when using strongly bactericidal antibiotics
What does Actinobacillus pleuropneumoniae cause and in what species?
Contagious pleuropneumonia (chronic) in swine (an acute respiratory disease that can become chronic)
What type are most isolates of Actinobacillus pleuropneumoniae and what do they require to grow?
Biotype 1 and they require V factor to grow
What does Biotype 2 of Actinobacillus pleuropneumoniae require for growth?
nothing
What do colonies of Actinobacillus pleuropneumoniae look like?
relatively small at 2-3 days and hemolytic but the degree of hemolysis varies considerably
What serotypes of Actinobacillus pleuropneumoniae predominate in the US?
serotypes 1, 3, 5, 7
What toxins does Actinobacillus pleuropneumoniae produce and what do they have a high degree of homology to?
four RTX type toxins (Apx1, Apx2, Apx3, Apx4); the alpha hemolysin of E. coli and the leukotoxin of Mannheimia haemolytica
Which RTX toxin of Actinobacillus pleuropneumoniae only grow in vivo?
Apx4
What is the natural habitat of Actinobacillus pleuropneumoniae?
it is carried in the upper respiratory tract of swine
In endemically infected herds, when are piglets infected with Actinobacillus pleuropneumoniae?
as colostral immunity wanes and mild disease usually results
What does the acute form of Actinobacillus pleuropneumoniae look like in older susceptible swine?
it is an exudative and proliferative bronchopneumonia with fibrinous pleuritis along with anorexia, emesis, fever, and hemorrhaging from the mouth and nose
When pigs are infected with the peracute form of Actinobacillus pleuropneumoniae how quickly can death occur?
within 8 hours
Pigs that recover from an Actinobacillus pleuropneumoniae infection have what lesions remaining?
abcesses and pleural adhesions
How do pigs develop immunity to an Actinobacillus pleuropneumoniae infection?
they have to survive it
Are there any bacterins against Actinobacillus pleuropneumoniae infection?
yes against serotypes 1 and 5
What is the advised treatment for Actinobacillus pleuropneumoniae infections?
penicillin, tetracycline, and tiamulin but the organism develops resistance easily
What does Actinobacillus suis cause in 1-8 week old pigs?
fatal acute septicemia
In older pigs, what has Actinobacillus suis been associated with?
arthritis, pneumonia, subcutaneous abscesses and a variety of other infections
What do colonies of Actinobacillus suis look like?
small, beta hemolytic colonies
What is required for growth of Actinobacillus suis cultures?
none - it does not need a staph nurse or NAD
Does Actinobacillus suis grow on MacConkey?
yes
What toxins does Actinobacillus suis produce?
RTX toxins (Apx1 and Apx2)
What is the natural habitat of Actinobacillus suis?
it is carried in the tonsils and nasal passages of healthy pigs at any age and can also be recovered from the vagina of sows
What is the pathogenesis of Actinobacillus suis infection?
Infection probably occurs via the upper respiratory tract, but invasion through skin lesions or other routes cannot be ruled out. The organism spreads rapidly throughout the body causing septicemia with acute death in young pigs and arthritis, pneumonia, and skin lesions in pigs older than 3 months of age
How is Actinobacillus suis infection in pigs be treated?
with antibiotics, but it is difficult to treat in time to save the pigs
What does Actinobacillus salpingitidis cause and in what species?
salpingitis and peritonitis in laying hens
Where is Actinobacillus seminis found?
in sheep in south Africa
Where does Actinobacillus seminis localize?
in the epididymis and testes
What does Acintobacillus seminis cause?
abortion in sheep and decreased fertility in the ram
What is the natural habitat of Actinobacillus seminis?
it is a normalpart of the microbial flora of the preputial and penile mucosa of the ram
What does Actinobacillus actinomycetemcomitans cause and in what species?
human endocarditis, meningitis, osteomyelitis, and periodontitis
What are the main ecological sites of residence for Actinobacillus actinomycetemcomitans?
dental plaque, periodontal pockets, and gingival sulci
What type of toxin does Actinobacillus actinomycetemcomitans produce?
a potent leukotoxin
