Microbiology-Anthrax and Plague Flashcards Preview

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Flashcards in Microbiology-Anthrax and Plague Deck (14)
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1
Q

When is anthrax contagious?

A

Never, the spores are the only contagious form and we don’t produce spores.

2
Q

Watery diarrhea from Chinese rice sitting out all day

A

Bacillus cereus spores

3
Q

Spore-forming gram-positive rods

A

Bacillus (aerobes) and clostridia (anaerobes). They sporulate from a vegetative rod to a spore and then germinate into a rod (bacillus anthracis chains shown below).

4
Q

Virulence factors of bacillus anthracis

A

Poly D-glutamic acid capsule (evades phagocytosis), replicates in blood stream, produces EDEMA TOXIN = edema factor (EF=A subunit) + protective antigen (PA=B subunit), produces LETHAL TOXIN = lethal factor (LF=A subunit) + protective antigen (PA=B subunit).

5
Q

Antibody to what region of bacillus anthracis neutralizes the toxin?

A

Anti-PA antibody. This prevents PA from binding to macrophages and forming a pore so the A subunits can enter.

6
Q

Function of B. anthracis edema factor?

A

Calmodulin-dependent bacterial adenylate cyclase. Causes fluid accumulation at site of infection. (like pertussis).

7
Q

Function of B. anthracis lethal factor?

A

Zinc-metaloprotease that cleaves MAPKK -> disrupts MAPK signal transduction in macrophages -> inactivates macrophages and minimizes immune response.

8
Q

B. anthracis reservoir

A

Soil, especially in grazing goats, cattle and sheep hides. Can also get from contaminated meat and IV drug abuse (heroin wrapped in goat skin).

9
Q

3 manifestations of anthrax

A

CUTANEOUS (papules -> central necrosis -> black eschar, painless, edematous, resolves 90% of time). GASTROINTESTINAL: ingestion of spore-contaminated meat, ulcers at site of invasion, regional lymphadenopathy, edema, hemorrhage, sepsis, 50% mortality. INHALATIONAL (

10
Q

Prophylaxis for inhalational anthrax

A

Ciprofloxacin/doxycycline + clindamycin + rifampin for 60 days!

11
Q

Licensed anthrax vaccine

A

Non-encapsulated, attenuated live vaccine

12
Q

Lab characteristics of the bacteria that causes plague.

A

Yersinia pestis: gram-negative rod that grows on MacConkey’s agar and stains with Wayson’s stain (looks like safety pins).

13
Q

Only type of plague that transfers person to person

A

Pneumonic plague (middle ages), all other plagues need fleas to transfer the bacteria from the reservoir (rats, squirrels, prairie dogs, mice, cats, rabbits) to humans.

14
Q

Pathogenesis of plague

A

Flea regurgitates bacteria on bite -> Phagocytosis -> Released from monocytes -> Lymphatics -> Bubo -> Resolution or Dissemination -> Bacteremia w/pneumonia, meningitis and/or septic shock.