Unit 3: Gram Negative Anaerobic Bacteria Flashcards
Describe the general characteristics of gram-negative anaerobic bacteria.
nonsporforming, usually nonmotile, and obligately anaerobic
What lesions are gram-negative anaerobic bacteria frequently isolated from?
abscesses, foot rot, necrotic lesions, septicemia, and urinary tract infections
What is the natural habitat of gram-negative anaerobic bacteria?
they are commensals of the GI tract
Necrobacillosis is the general term for infection with what?
Fusobacterium necrophorum
Generally, what lesions are caused by Fusobacterium necrophorum?
necrotic lesions in warm-blooded animals
What is the morphology of Fusobacterium necrophorum?
long filaments with some short coccoid elements, some rods may be swollen
What does Fusobacterium necrophorum require for growth?
5-10% CO2, serum, yeast extract, and reducing agent
What are the two subspecies of Fusobacterium necrophorum?
funduliforme and necrophorum
What animals is Fusobacterium necrophorum subspecies necrophorum more virulent in?
cattle
What host does Fusobacterium necrophorum subspecies funduliforme typically cause disease in?
humans
What toxins are produced by Fusobacterium necrophorum?
Leukotoxin and LPS
What is the function of the leukotoxin produced by Fusobacterium necrophorum?
it is toxic for neutrophils, macrophages, and hepatocytes - it induces apoptosis at low concentrations and lyses cells at higher concentrations
How does Fusobacterium necrophorum enter tissues?
through wounds and other damaged tissues
What is the ‘typical’ lesion caused by Fusobacterium necrophorum?
necrosis and abscessation with a putrid odor
What other bacteria are associated with Fusobacterium necrophorum infections?
Trueperella pyogenes and Dichelobacter nodosus
How does Trueperella pyogenes stimulate growth and invasiveness of Fusobacterium necrophorum?
by using up oxygen and secreting a compound to stimulate growth
What disease processes is Fusobacterium necrophorum associated with in cattle?
foot rot, liver abscesses, calf diphtheria, metritis and lesions of the udder and teats
What can foot rot progress to?
severe arthritis
What subspecies of Fusobacterium necrophorum is found in bovine liver abscesses and how does it enter?
subspecies necrophorum - via rumen lesions (the rumen lesions contain a mixutre of both subspecies)
What is calf diphtheria?
infection of the mouth and pharynx usually in bucket fed calves or under conditions of poor hygiene
How can calf diphtheria lead to death?
the lesions may extend to the larynx and necrotic material may be aspirated and lead to fatal pneumonia
What other bacteria are found with Fusobacterium necrophorum in cattle with purulent post-partum metritis?
Trueperella pyogenes and Escherichia coli
What does Fusobacterium necrophorum cause in sheep?
ovine interdigital dermatitis
What other bacteria is found with Fusobacterium necrophorum in sheep?
Dichelobacter nodosus
What does Fusobacterium necrophorum cause in horses?
- thrush - infection of the frog of the horse foot
- infection associated with ulcerative dermaitis
- Quittor
What is Quittor?
a chronic, supparative inflammation of the lateral cartilage of the third phalynx
What does Fusobacterium necrophorum cause in swine?
ulcerative stomatitis (sore mouth) and bull nose (infection of the subcutaneous tissues of the face associated with the use of nose rings)
How do you diagnose a Fusobacterium necrophorum infection?
gram-stained smears and cultures
What is used for immunity against Fusobacterium necrophorum infections?
leukotoxoid vaccines in feedlot cattle to limit liver abscesses
most adult cattle have anitbody against the organism
How do you treat Fusobacterium necrophorum infections?
antibiotics – tetracycline
topical agents in foot rot
What is considered to be the cause of contagious foot rot in sheep?
Dichelobacter nodosus
What is the morphology of Dichelobacter nodosus?
relatively large rod, often with terminal enlargements on both ends - straight to slightly curved
What does Dichelobacter nodosus require for growth?
10% horse serum - powedered sheep horn or sheep hoof helps
What is the natural habitat of Dichelobacter nodosus?
obligate parasites of the hoof of sheep, goats, and cattle and survive only a few days in soil
What causes Dichelobacter nodosus infection to spread in sheep?
when they are grazing in lush damp pasture in moderate weather
What is the pathogenesis of contagious foot rot in sheep?
Fusobacterium necrophorum invades first and damages the epidermis. Dichelobacter nodosus invades and produces a powerful protease that digests hoof and a heat stable soluble factor that stimulates the growth of Fusobacterium necrophorum. Trueperella pyogenes removes O2 and thereby stimulatates anaerobic growth
What does ‘successful’ immunization against Dichelobacter nodusus require?
a high content of the fimbriae of the correct types - two doses with booster prior to the release to pasture
How is contagious foot rot in sheep treated?
clean up the foot and use topical spray, use a foot bath, or administer antibiotics and sulfas
In regards to oxygen, what type of organism is Porphyrmonas levii?
obligate anaerobe
Porphyrmonas levii is considered a major associative agent of ______ _______.
bovine footrot
