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FA1 Bacteriology > Lecture 7 9/25/23 > Flashcards

Lecture 7 9/25/23 Flashcards

1
Q

What is the main defining feature of Bacillus sp.?

A

endospore-forming rods

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2
Q

Which Bacillus species is of great importance, and what does it cause?

A

B. anthracis, which causes anthrax

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3
Q

What are the characteristics of B. anthracis?

A

-sporadic cases
-most seen in cattle
-transmit through soil contaminated with spores
-biological warfare agent

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4
Q

What are the two virulence factors of B. anthracis?

A

-anti-phagocytic capsule
-tripartite exotoxin

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5
Q

Why is the anti-phagocytic capsule of B. anthracis a diagnostic feature?

A

the polychromatic methylene blue capsule stain will stain the capsule as a pink shadow

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6
Q

What are the three proteins in the tripartite toxin?

A

-edema factor
-lethal factor
-protective antigen

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7
Q

What does the anthrax toxin do?

A

increases vascular permeability and cell necrosis

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8
Q

Which B. anthracis strains are virulent?

A

only those that are both encapsulated and toxigenic (contain both virulence factors)

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9
Q

How is B. anthracis transmitted?

A

ingestion, inhalation, or skin contact with endospores

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10
Q

What is important about B. anthracis longevitity?

A

spores can persist in the soil for decades

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11
Q

What are the predisposing factors for anthrax cases?

A

-previous anthrax deaths
-flooding that causes soil rearrangement
-alkaline, calcium- and nitrogen-rich soils
-warm temps
-drought conditions that cause closer foraging

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12
Q

What type of anthrax do ruminants develop?

A

per-acute septicemia

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13
Q

What is the order of severity for anthrax disease in animals?

A

-cattle
-sheep
-horses
-goats
-dogs
-pigs

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14
Q

What is the clinical manifestation of anthrax in cattle?

A

found dead with un-clotted, dark bloody fluid coming from orifices

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15
Q

What are the signs of anthrax?

A

-high fever
-bleeding
-shock
-resp. distress
-dark, un-clotted blood
-large, gelatinous spleen

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16
Q

What should you do if you suspect an animal died of anthrax?

A

-do not conduct a field necropsy
-inform necessary official/report disease

17
Q

How can anthrax be diagnosed?

A

-examination of peripheral blood smears stained with polychromatic methylene blue
-cultures
-PCR

18
Q

How can anthrax be controlled?

A

vaccination
-proper carcass disposal
-prophylactic antimicrobial therapy

19
Q

Which listeria sp. is of importance?

A

Listeria monocytogenes

20
Q

What are the important characteristics of Listeria sp.?

A

-facultative intracellular
-capable of growing at 4 deg. C

21
Q

What are the virulence factors associated with Listeria sp.?

A

-internalin: adhesion, entry, phagocytosis
-listeriolysin O: req. for intracellular rep.
-Act A: allows intracellular movement to adjacent cells

22
Q

Why is Act A an important virulence factor?

A

movement from cell to cell intracellularly helps keep the bacteria undetected by the immune system

23
Q

What are the potential outcomes of Listeria infection?

A

-local cell death and focal microabscesses in brain
-septicemia

24
Q

What causes Listeria infection in ruminants?

A

feeding poor-quality, infected silage

25
Q

What are the clinical signs of Listeria circling disease/brain infection?

A

-unilateral trigeminal and facial nerve paralysis
-purulent endophthalmitis

26
Q

Which species commonly develop septicemia as a result of Listeria infection?

A

-humans
-monogastrics
-newborn animals

27
Q

What are the major lesions of septicemic listeriosis in monogastrics and young ruminants?

A

-focal hepatic necrosis
-hemorrhagic gastroenteritis

28
Q

How can Listeria sp. be diagnosed?

A

-history and symptoms
-visualization of microabscesses on histology
-Listeria enrichment culture

29
Q

What are the characteristics of Listeria treatment and prevention?

A

-not attempted with CNS disease
-treated with penicillin or ampicillin/gentamicin combo
-no vaccine
-avoid poor silage (animals) and high risk foods (humans)

30
Q

What are the characteristics of Erysipelothrix rhusiopathiae?

A

-most common in pigs and turkeys
-pigs are important reservoirs

31
Q

What condition is caused by Erysipelothrix sp. in pigs?

A

-diamond skin disease/swine erysipelas
-vasculitis of blood vessels

32
Q

What causes outbreaks of Erysipelothrix sp. in sheep?

A

dipping sheep in contaminated solutions following shearing

33
Q

How do human erysipeloid and human erysipelas differ?

A

-human erysipeloid is caused by Erysipelothrix sp.
-human erysipelas is caused by Strep. sp.

34
Q

How can Erysipelothrix sp. be diagnosed?

A

-aerobic culture of blood and organs
-PCR

35
Q

What antibiotics are Erysipelothrix sp. intrinsically resistant to?

A

-vancomycin
-aminoglycosides
-sulphonamides

36
Q

How can Erysipelothrix sp. be controlled?

A

-treatment/isolation of infected animals
-culling
-good hygiene
-vx

FA1 Bacteriology (21 decks)

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