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