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Infectious Agents > Bacillus > Flashcards

Bacillus Flashcards

1
Q

Most bacilli are _____

A

Ubiquitous soil, dust, air, and water saprophytes

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2
Q

Bacillus spp.

A

Large, gram-pos, aerobic or facultative anaerobic rods

- produce endospores only under aerobic conditions

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3
Q

Clostridium spp.

A

Obligate anaerobic, large gram-pos rods that form endospores

- only the spores of clostridium can survive oxygen

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4
Q

B. cereus

A
  • food poisoning (enterotoxin) –> hemolytic exotoxin
  • gangrenous bovine mastitis (occurs with spore or vegetative form)
  • supperative wound infections
  • common soil saphrophyte and lab contaminant
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5
Q

B. larvae

A
  • apiculture
  • bee foul brood
  • use oxytetracycline to treat hives*
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6
Q

B. thruingiensis

A

Biologic insecticide

  • produces insecticidal crystal protein
  • exotoxin used in transgenic plants
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7
Q

B. polymyxa

A

Produces protein ionophore antibiotic

- polymyxin B

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8
Q

B. colistinus

A

Produces protein ionophore antibiotic

- colistin

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9
Q

Other names for B. anthracis

A
  • milzbrand
  • charbon
  • malignant carbuncle
  • woolsorter’s disease
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10
Q

What animals are resistant to Anthrax?

A

Birds and poikilotherms

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11
Q

What animals are most susceptible to anthrax, in order from greatest to least?

A
  • cattle
  • deer
  • sheep
  • people
  • goats
  • horses
  • swine
  • dogs
  • also buffalo
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12
Q

What is the infectious particle of anthrax?

A

The endospore

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13
Q

What form of anthrax do swine and carnivores get?

A

Are usually resistant, but can get the oral or pharyngeal form from ingestion
- GI infection accompanied by hematemesis and bloody diarrhea

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14
Q

Anthrax is not seen in ________ animals

A

Cold blooded

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15
Q

What is the major characteristic of anthrax?

A

Blood does not clot, will see frank blood coming from all body openings (even after death)

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16
Q

Endospores will survive ______ in the soil

A

“Forever” until the conditions are right for germination

- most resistant form of life

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17
Q

Autoclave

A

Set up specifically to kill spores

- 121 C, 15 psi, 15 min

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18
Q

Are vegetative anthrax cells easy to kill?

A

Yes, are no more resistant than other bacteria

  • die rapidly (30-60 min) in unopened carcasses due to aerobic nature of the organism
  • will form spores at air interfaces with tissues and exuded hemorrhagic fluids
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19
Q

Endemic areas of anthrax

A
  • Mississippi river delta (#1)
  • Texas gulf coast
  • SE South Dakota
  • NE Nebraska
  • Sacramento/San Joaquin Valley
  • Northwest Territory Great Slave Lake area
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20
Q

What are the environmental requirements for anthrax growth?

A
  • alkaline soil
  • high nitrogen content from decaying vegetation, alternating rainy and dry spells
  • temp over 60 F
  • soils rich in calcium and nitrogen, spread by periodic flooding
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21
Q

Rainy periods allow for ______ formation, while dry periods allow for ______ formation

A

Vegetative cell; spore

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22
Q

Soil flora must lack certain______

A

Streptomyctes spp.

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23
Q

How do alternating wet and dry periods contribute to epidemics?

A

Formation of large numbers of spores

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24
Q

What animals are common to overgrazing and ingestion of spores?

A

Cattle and horses

25
Other sources of anthrax
- bone meal - animal by produces - wool - boar bristle - brushes - hides - bongo drums - voodoo dolls
26
Spread of anthrax occurs by
- animal amplification - flies - carrion eaters - vultures
27
Septicemic form of anthrax
Primarily infects herbivores - incubation period: 3-7 days - fatal 1-2 hr after first signs or by 24 hrs - symptoms: high fever, bleeding (more prolonged in horse than in cow) - horses and swine are reported to have low number of organisms in circulation during septicemia * equivalent to respiratory form!*
28
Cutaneous form of anthrax
Intensely dark, painless edematous eschar - ulcer with necroticcenter - many become septicemic - heals rapidly with antibiotic therapy - most common in people, reported in rabbits, swine, and horses
29
Pharyngeal form of anthrax
Seen in swine, dog, cat - subacute to chronic carbuncular lesions of jowl and tongue - swelling of lips, head, and throat, severe gastroenteritis - common in carnivores and scavengers
30
Intestinal form of anthrax
Seen in people, dog, cat - bloody diarrhea, hematemesis - A. bacillus grows rapidly on cut surface of boiled vegetables --> growth spreads dully, dry, mealy and grayish white color - sporulation occurs early and profusely on these substances
31
Respiratory (pneumonic) form of anthrax
Seen in people, usually becomes septicemic and rapidly fatal
32
Meningitis form of anthrax
CNS sighs, only recognized in people and is generally rare (only occurred once) - animals will typically die before meningeal form occurs
33
Pathogenesis of anthrax: step 1
Ingestion, inhalation, skin exposure by spore contact - spores germinate at site of entry - may localize in regional lymph nodes or spread via lymphatics and blood
34
Poly-D-glutamate capsule
Antiphagocytic, antiopsonic, nonimmunogenic and nonantigenic | *is the only protein based capsule!*
35
Virulence requirements for B. anthracis
Requires 2 different plasmids | - 1 coding for capsule (PAOX-1), 1 coding for toxins (PAOX-2)
36
Toxin actions
- damages and kills phagocytes - increase capillary cell permeability - prevents clotting - blocks opsonization (activity of C3) - capillary thrombosis occurs - blood pressure falls - shock and death
37
Toxin is a product of a ______ plasmid
110 Mdal
38
Toxin structure
Tripartite subunit toxin, where 1 unit binds and 2 units are toxic - exotoxin has AB structure where B bind to host cell and A enters cytoplasm
39
Edema factor
Adenylate cyclase | - Na: K pump affected
40
Protective antigen
2, binds to cell receptors, translocates EF and LF | - 63kDa protein forming a transmembrane channel
41
Lethal factor
3, Cleaves and inactivates nitrogen activated protein kinase kinases (MAPKK1, MAPKK2) - enzymes control cell growth, embryonic development, oocyte maturation - MAPK regulates activity via phosphorylation - LF cleaves off enzyme responsible for activating MAPK
42
LF is a ______ that cleaves the amino terminus
Protease
43
Of the 3 components of toxin, which is the dominant virulence factor?
Lethal factor | - A776 amino acid protein with a putative zinc binding site
44
The toxin is originally produced as a ______
240 kDa protein | - is post-translationally cleaved to 3 active fragments (EF, PA, LF)
45
What conditions are the toxins not produced under?
42 C (possibly creates resistance in birds)
46
Method of anthrax interaction with target cells
PA binds to host cell surface receptor R --> host cell surface protease cleaves PA, activating it to bind EF and LF ---> EF and LF now competitively bind to high affinity receptor --> EF or LF, PA and R are endocytosed as a ternary complex --> EF is adenylate cyclase, increasing cAMP inactivating Na/K pump causing edema and cell death
47
Splenomegaly
Blackberry jam appearance of spleen | - also occurs with other pathogens, is not specific to anthrax
48
What to do if anthrax is suspected?
Aspirate peripheral blood from jugular vein for stains and culture - do not take samples from ear, spleen, or tissues!
49
Ruminants
Use a vaccutainer and a red top tube
50
Horses and swine
Aseptic collection of spleen or liver may be necessary due to low levels of organisms in blood during septicemia
51
Do you open the carcass?
NO!!! - cremate or bury (6ft) in lime (calcium oxide) - clean tools with 1.0% bleach or strong disinfectants - carcass should not be moved to prevent contamination
52
How to stain anthrax smears
Use Wright's, Giemsa, or methelyene blue, or Gram's stain - in vivo: large blue bacilli, single or short chains, squared off ends and pink capsules with polychromatic stains - no spores usually
53
Ascoli test
Done on environmental materials to determine if anthrax is present - use high titered antisera
54
Treatment
Penicillin (cidal) or tetracycline (static) | - effective only before a lethal concentration of toxins accumulates
55
During outbreaks you _____ the sick and ______ normal
Treat; vaccinate | - do not do both!
56
Anthrax immunity
Mainly humoral, antitoxic
57
Sterne strain
Has plasmid for toxins, but not for capsule - rough, avirulent, nonencapsulated, spore vaccine - 2 doses and annual booster in enzootic area --> immunity develops about 7 days after vaccination - 1 does in epizootic (no antibiotics), live vaccine produces septicemia for up to 60 days - used in all livestock
58
Alum-precipitated supernatant toxoid vaccine
Available for people - plasmid has been isolated and segments cloned to produce a more efficacious toxoid - not commercially available

Infectious Agents (44 decks)

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