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Infectious Agents > Exam 2: Bacillus > Flashcards

Exam 2: Bacillus Flashcards

1
Q

What are Bacillus spp.?

A

Large gram positive, aerobic or facultative anaerobic rods that produce endospores only under aerobic conditions

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2
Q

What are Clostridium spp.?

A

Obligate anaerobic, large, gram positive rods that form endospores

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3
Q

What can only spores of clostridium survive?

A

Oxygen

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4
Q

What is the significance of B. anthracis?

A

Mammalian pathogen

Anthrax

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5
Q

What is the significance of B. cereus?

A

Food poisoningm, gangreous bovine mastitis, supperative wound infections
Common soil saprophyte and lab contaminant

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6
Q

What is the significance of B. larvae?

A

In apiculture

Bee foul brood

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7
Q

What is the significance of B. thuringiensis?

A

Biologic insecticide
Produces insecticidal crystal protein
Exotoxin used in transgenic plants

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8
Q

What is the significance of B. polymyxa?

A

Produces protein ionophore antibiotic

Polymyxin B.

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9
Q

What is the significance of B. colistinus?

A

Produces protein ionophore antibiotic

Colistin

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10
Q

What is the most significant pathogen of the genus in vet med?

A

B. anthracis

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11
Q

What are the susceptible species (from most to least) to B. anthracis?

A 
Cattle
Deer
Sheep
People
Goats
Horses
Swine
Dogs
Birds and poikilotherms are resistant
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12
Q

What is the septicemic form of B. anthracis usually acquired through?

A

Inhalation

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13
Q

How quickly can the septicemic form be fatal?

A

In 4 hours

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14
Q

What form of B. anthracis do humans normally get?

A

Skin form, but they can also inhale

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15
Q

What is the incubation period in humans before septicemia?

A

5-7 days

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16
Q

Does human-to-human transmission occur?

A

Not as far as we know

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17
Q

What form of B. anthracis can swine and strict carnivores acquire?

A

Oral/pharyngeal form

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18
Q

What is the infections particle of B. anthracis?

A

Endospore (most resistant form of life)

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19
Q

How can an endospore be killed?

A

Autoclave (121 degrees C, 15 psi, 15 min)*
Hot air oven
Formalin
Heat-fixed slides

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20
Q

What happens to vegetative cells in unopened carcasses?

A

They are easily killed and die rapidly as this is an anerobic environment, but their spores will live on at air interfces

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21
Q

What are the endemic areas of B. anthracis in order of most occurring?

A 
Mississippi river delta
Texas gulf coast
SE South Dakota
NE Nebraska
Sacramento/San Joaquin Valleys
NW territory Great Slave Lake area
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22
Q

What soils can B. anthracis be found in?

A

Alkaline soil
High N content
Soils rich in Ca and N

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23
Q

How can B. anthracis be spread?

A

By periodic flooding

24
Q

What must soil flora lack?

A

Certain Sterptomyctes spp.

25
Q

When do spores form?

A

During dry periods

26
Q

What contributes to epidemics?

A

Alternating wet and dry periods

27
Q

In an outbreak, what are large numbers of B. anthracis shed through?

A

Animal amplification

28
Q

What are the 6 primary forms of disease with B. anthracis?

A 
Septicemic
Cutaneous form
Pharyngeal form
Intestinal form
Respiratory form
Meningitis
29
Q

Describe the septicemic form of disease

A

Herbivores: incubation of 3-7 days, fatal after 1-2 hours after first signs
High fever, bleeding, more prolonged in horse than cow
Horse and swine reported to have low number of organisms in circulation during septicemia

30
Q

Describe the cutaneous form of disease

A

Intensely dark, relatively painless edematous eschar
Ulcer with necrotic center (malignant carbuncle)
May become septicemic, but heals rapidly with antibiotic therapy
Reported in people, rabbits, swine, and horses

31
Q

Describe the pharyngeal form of disease

A

Reported in swine, dogs, and cats
Subacute to chronic carbuncular lesions of jowl and tongue
Swelling of lips, head, and throat
Severe gastroenteritis

32
Q

Describe the intestinal form of disease

A

Reported in people, dogs, and cats

B. anthracis grows readily on cut surface of boiled veggies and sporation occurs

33
Q

Describe the respiratory from of disease

A

In people, usually becomes septicemic and rapidly fatal

34
Q

Describe the meningitis form of disease

A

CNS signs, only recognized in people

Rare

35
Q

What is the pathogenesis of anthrax?

A
  1. Ingestion, inhalation, skin exposure by spore contact
  2. Poly-D-glutamate capsule
  3. To be virulent, it requires 2 different plasmids (1 coding for capsule and 1 coding for toxins)
  4. Sheer numbers of anthrax overwhelm spleen and a single, multicomponent protein exotoxin is produced
36
Q

Describe Poly-D-glutamate capsule

A

Antiphagocytic
Antiopsonic
Nonimmunogenic
Nonantigenic

37
Q

What are the toxin actions from the exotoxin produced?

A 
Damage/kill phagocytes
Increase capillary permeability
Prevent clotting
Block opsonization
Capillary thrombosis occurs
BP falls
Shock and death follow
38
Q

What is the toxin a product of?

A

A 110 Mdal plasmid

39
Q

What is this toxin specifically?

A

Tripartite subunit toxin (1 unit binds, 2 units are toxic)

40
Q

What is the structure of the subunit toxin?

A

A:B structure (B binds and A is active)

41
Q

Describe the toxin

A 
Edema factor (EF)
Protective antigen
Lethal factor (LF)
42
Q

What does edema factor affect?

A

Na/K pump

43
Q

What does protective antigen do?

A

Binds to cell receptor and allows EF and LF to enter

44
Q

Describe lethal factor

A

Dominant virulence factor

Cleaves and inactivates MAPKK1 and MAPKK2, which are enzymes in charge of cell growth

45
Q

Why is it believed that birds are resistant to anthrax?

A

The toxin is not produced at 42 degrees C

46
Q

What would you see from an animal that should make you think about anthrax?

A

Any sudden death with bleeding from all body openings, unclotted dark blood, delayed rigor mortis

47
Q

Where should the blood sample for anthrax come from?

A

Jugular veins

48
Q

Why should you be quick to bring back a sample on anthrax?

A

If the animal has been dead more than 1 hour, it is less likely to culture

49
Q

Why should you not open a carcass believed to have anthrax?

A

Once exposed to air, spores will be released and infect

50
Q

What stain smears for anthrax?

A

Wrights, giemsa, methylene blue, or gram stain

51
Q

What is anthrax like in vivo?

A

A large blue bacilli, single or short chains, no spores usually

52
Q

What are B. anthracis antigens demonstrated in extracts from contaminated products by?

A

Ascoli test

53
Q

What is the treatment for anthrax?

A

Penicillin (cidal) or tetracycline (static), which are only effective early before lethal concentration of anthrax accumulates
Penicillin resistant strains are isolated in Mississippi

54
Q

What is the immunity to anthrax like?

A

Mainly humoral, antitoxic

55
Q

Why is the sterne strain used mostly in US?

A

Has plasmid for toxins, but not for capsule

56
Q

What is the vaccine available for people?

A

Alum-precipitate supernatant toxoid

Infectious Agents (38 decks)

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