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Bacteria > Lecture 14 > Flashcards

Lecture 14 Flashcards

1
Q

Describe the appearance & metabolism of non-spore forming anaerobes

A

Gram negative

Obligate anaerobes

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2
Q

What pathological conditions do we normally find non-spore forming anaerobes?

A

necrotic & suppurative

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3
Q

What is the appearance of Fusobacterium necrophorum? (2)

A

Gram negative

Long, slender rods

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4
Q

What is the appearance of Dichelobacter nodosus? (3)

A

Gram negative

Straight or slightly curved rods

Characteristic swellings at both ends

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5
Q

What is the appearance of Prevotella melaninogenica? (3)

A

Gram negative

Coccobacilli

Rounded ends

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6
Q

Where are non-sporing forming anaerobes found? & when do they become a prob?

A

Normal microbiota

When they enter normally sterile sites & cause tissues to be ischemic

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7
Q

What part of the microbiota is Fusobacterium found?

A

GIT

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8
Q

What part of the microbiota is DIchelobacter nodosus found?

A

ruminant foot

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9
Q

What part of the microbiota are prevotella spp found?

A

mouth of a variety of spp

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10
Q

What is the virulence factor of Fusobacterium necrophorum?

A

Leukotoxin - lysis of bovine leukocytes & toxic towards hepatocytes

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11
Q

What are the virulence factors for Dichelobacter nodosus? (2)

A

Type IV fimbriae - motility, adherence & facilitates secretion of serine proteases

Serine proteases - degradation of hoof PROs

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12
Q

How do we base tx for non-spore forming anaerobes?

A

Site of infection, not ID

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13
Q

Why is Fusobacterium necrophorum problematic?

A

It allows invasion of other bacteria

Releases a leukotoxin causing tissue damage enabling other microbes to invade, colonize & replicate

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14
Q

What microbe is assoc with Fusobacterium necrophorum infection in cattle?

A

Trueperella pyogenes

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15
Q

How does Fusobacterium necrophorum infection in cattle present? (3)

A

Calf diphtheria - necrotic foci on larynx, trachea & buccal cavity
Symptoms: fever, depression, excessive salivation

Liver abscesses in feedlot cattle

Lesions on hoof following trimming (foul of the foot)

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16
Q

What is the pathogenesis of calf diphtheria caused by Fusobacterium necrophorum?

A

Abrasions of pharynx due to rough feed provide portal of entry

Progresses to fatal pneumonia if untreated

17
Q

What is the pathogenesis of calf liver abscesses caused by Fusobacterium necrophorum?

A

Leukotoxins kill leukocytes in the liver resulting in abscesses

Septic embolism following rumenitis

18
Q

What is the appearance of Fusobacterium necrophorum? (3)

A

Thin rods

Gram negative

Irregular staining

19
Q

What disease does Dichelobacter nodosus cause in sheep?

A

Foot rot (ovine digital dermatitis)

20
Q

What microbe is often assoc with Dichelobacter nodosus causing ovine foot rot?

A

Fusobacterium necrophorum

21
Q

How do sheep present with foot rot due to Dichelobacter nodosus? What is infection assoc with?

A

Lameness
Underrunning of the hoof
Separation of hoof from skin horn junction
Foul smelling exudate

Infection associated with warm & wet conditions

22
Q

How does Dichelobacter nodosus do in the envr?

A

Doesn’t readily survive

Primary reservoir is infected sheep - transmitted via transiently contained enviers (tricks, paddocks etc.)

23
Q

How should you handle samples of non-spore forming anaerobes?

A

Avoid contamination (since they are apart of the microbiota)

Aerobic swabs are a must

24
Q

What specimens should you take to test for non-spore forming anaerobes?

A

Purulent material from abscesses

Discharges

Tissue specimens - take larger tissue to maintain microenvrs

25
Q

How are non-spore forming anaerobes dx in lab? (3)

A

Dilute carbol fuchsin stain of smear (since they are gram neg)

Anaerobic culture - blood agar with special supplements & requires an anaerobic chamber

PCR to identify

26
Q

Do non-spore forming anaerobes pose a zoonotic risk?

A

Not really since they are apart of the microbiota

Although, Fusobacterium, Porphyromonas & Prevotella have all been isolated from dog & cat bites

27
Q

How do you tx foot rot? What do we need to be aware of?

A

Tx depends on site of infection

Combo of systemic a/bs & topical antiseptics

Beware of copper toxicity in sheep when using Cu based products

28
Q

How do you tx Fusobacterium necrophorum?

A

penicillin

29
Q

How do you control non-spore forming anaerobes?

A

Dietary management

Paddock & pasture management to keep feet dry & clean

30
Q

Describe the appearance of Capnocytophaga canimorsus?

A

Gram negative rods

31
Q

Where is Capnocytophaga canimorsus found?

A

Mouths of 74% of healthy dogs

32
Q

Does Capnocytophaga canimorsus pose a zoonotic risk?

A

Yes, infections via dog bites & sometimes cat bites or scratches

33
Q

What human pops does Capnocytophaga canimorsus pose a threat to? (4)

A

Particularly, splenectomised people

Infections more common in older adults

Immunocompromised indivs

Alcoholism + hepatic cirrhosis

Bacteria (16 decks)

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