Unit 3: Gram Negative Anaerobic Bacteria

Question 1

Describe the general characteristics of gram-negative anaerobic bacteria.

Answer 1

nonsporforming, usually nonmotile, and obligately anaerobic

Question 2

What lesions are gram-negative anaerobic bacteria frequently isolated from?

Answer 2

abscesses, foot rot, necrotic lesions, septicemia, and urinary tract infections

Question 3

What is the natural habitat of gram-negative anaerobic bacteria?

Answer 3

they are commensals of the GI tract

Question 4

Necrobacillosis is the general term for infection with what?

Answer 4

Fusobacterium necrophorum

Question 5

Generally, what lesions are caused by Fusobacterium necrophorum?

Answer 5

necrotic lesions in warm-blooded animals

Question 6

What is the morphology of Fusobacterium necrophorum?

Answer 6

long filaments with some short coccoid elements, some rods may be swollen

Question 7

What does Fusobacterium necrophorum require for growth?

Answer 7

5-10% CO2, serum, yeast extract, and reducing agent

Question 8

What are the two subspecies of Fusobacterium necrophorum?

Answer 8

funduliforme and necrophorum

Question 9

What animals is Fusobacterium necrophorum subspecies necrophorum more virulent in?

Answer 9

cattle

Question 10

What host does Fusobacterium necrophorum subspecies funduliforme typically cause disease in?

Answer 10

humans

Question 11

What toxins are produced by Fusobacterium necrophorum?

Answer 11

Leukotoxin and LPS

Question 12

What is the function of the leukotoxin produced by Fusobacterium necrophorum?

Answer 12

it is toxic for neutrophils, macrophages, and hepatocytes - it induces apoptosis at low concentrations and lyses cells at higher concentrations

Question 13

How does Fusobacterium necrophorum enter tissues?

Answer 13

through wounds and other damaged tissues

Question 14

What is the ‘typical’ lesion caused by Fusobacterium necrophorum?

Answer 14

necrosis and abscessation with a putrid odor

Question 15

What other bacteria are associated with Fusobacterium necrophorum infections?

Answer 15

Trueperella pyogenes and Dichelobacter nodosus

Question 16

How does Trueperella pyogenes stimulate growth and invasiveness of Fusobacterium necrophorum?

Answer 16

by using up oxygen and secreting a compound to stimulate growth

Question 17

What disease processes is Fusobacterium necrophorum associated with in cattle?

Answer 17

foot rot, liver abscesses, calf diphtheria, metritis and lesions of the udder and teats

Question 18

What can foot rot progress to?

Answer 18

severe arthritis

Question 19

What subspecies of Fusobacterium necrophorum is found in bovine liver abscesses and how does it enter?

Answer 19

subspecies necrophorum - via rumen lesions (the rumen lesions contain a mixutre of both subspecies)

Question 20

What is calf diphtheria?

Answer 20

infection of the mouth and pharynx usually in bucket fed calves or under conditions of poor hygiene

Question 21

How can calf diphtheria lead to death?

Answer 21

the lesions may extend to the larynx and necrotic material may be aspirated and lead to fatal pneumonia

Question 22

What other bacteria are found with Fusobacterium necrophorum in cattle with purulent post-partum metritis?

Answer 22

Trueperella pyogenes and Escherichia coli

Question 23

What does Fusobacterium necrophorum cause in sheep?

Answer 23

ovine interdigital dermatitis

Question 24

What other bacteria is found with Fusobacterium necrophorum in sheep?

Answer 24

Dichelobacter nodosus

Question 25

What does Fusobacterium necrophorum cause in horses?

Answer 25

1. thrush - infection of the frog of the horse foot
2. infection associated with ulcerative dermaitis
3. Quittor

Question 26

What is Quittor?

Answer 26

a chronic, supparative inflammation of the lateral cartilage of the third phalynx

Question 27

What does Fusobacterium necrophorum cause in swine?

Answer 27

ulcerative stomatitis (sore mouth) and bull nose (infection of the subcutaneous tissues of the face associated with the use of nose rings)

Question 28

How do you diagnose a Fusobacterium necrophorum infection?

Answer 28

gram-stained smears and cultures

Question 29

What is used for immunity against Fusobacterium necrophorum infections?

Answer 29

leukotoxoid vaccines in feedlot cattle to limit liver abscesses
most adult cattle have anitbody against the organism

Question 30

How do you treat Fusobacterium necrophorum infections?

Answer 30

antibiotics – tetracycline

topical agents in foot rot

Question 31

What is considered to be the cause of contagious foot rot in sheep?

Answer 31

Dichelobacter nodosus

Question 32

What is the morphology of Dichelobacter nodosus?

Answer 32

relatively large rod, often with terminal enlargements on both ends - straight to slightly curved

Question 33

What does Dichelobacter nodosus require for growth?

Answer 33

10% horse serum - powedered sheep horn or sheep hoof helps

Question 34

What is the natural habitat of Dichelobacter nodosus?

Answer 34

obligate parasites of the hoof of sheep, goats, and cattle and survive only a few days in soil

Question 35

What causes Dichelobacter nodosus infection to spread in sheep?

Answer 35

when they are grazing in lush damp pasture in moderate weather

Question 36

What is the pathogenesis of contagious foot rot in sheep?

Answer 36

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

Question 37

What does ‘successful’ immunization against Dichelobacter nodusus require?

Answer 37

a high content of the fimbriae of the correct types - two doses with booster prior to the release to pasture

Question 38

How is contagious foot rot in sheep treated?

Answer 38

clean up the foot and use topical spray, use a foot bath, or administer antibiotics and sulfas

Question 39

In regards to oxygen, what type of organism is Porphyrmonas levii?

Answer 39

obligate anaerobe

Question 40

Porphyrmonas levii is considered a major associative agent of ______ _______.

Answer 40

bovine footrot