Micro - Anthrax

Question 1

B. anthracis = (G+, G-) (aerobe, anaerobe) (spore forming or not) (shape)

Answer 1

G+ facultative anaerobe, spore forming, rod

Question 2

Primary reservoir of naturally-occuring anthrax

Answer 2

Cows/soil

Question 3

Why don’t farmers contract natural anthrax?

Answer 3

Spores clump together and stick to soil

Question 4

How does B. anthrax look on blood smear/CSF?

Answer 4

BoX cars

Question 5

How long can anthrax spores remain viable in soil?

Answer 5

100 years

Question 6

Problem with anthrax infections?

Answer 6

Misdiagnosed

Question 7

Category A bioterrorism agents

Answer 7

Tularemia, anthrax, plague

Question 8

Category B bioterrorism agent

Answer 8

Brucella

Question 9

Two major virulence factors of anthrax

Answer 9

1. Antiphagocytic, non-antigenic capsule

2. Exotoxin

Question 10

Anthrax capsule made up of:

Answer 10

Poly-d-glutamic acid

Question 11

3 subunits of anthrax toxin and their function

Answer 11

B = protective antigen; binds to host cell receptors and facilitates endocytosis then entry into cytoplasm once inside cell
A1 = edema factor; AC that increases cAMP which causes swelling, mediastinal edema
A2 = lethal factor; MMP that inhibits MAPKs to disrupt cell signaling and innate immunity

Question 12

What causes swelling in cutaneous anthrax infection?

Answer 12

Edema factor (A subunit) of toxin
(ON TEST!!!)

Question 13

Two possible anthrax disease

Answer 13

Cutaneous or inhalational

Question 14

Characteristic lesion of cutaneous anthrax

Answer 14

Swollen eschar (necrotic, black skin lesion)

Question 15

Two phases of inhalational anthrax

Answer 15

1. Flu-like sx + SOB + N/V + CP

2. Hemorrhagic mediastinitis + pleural effusion

Question 16

Which is more fatal if untreated: cutaneous or inhalational anthrax?

Answer 16

Inhalational (universally fatal; cutaneous only 20% fatal)

Question 17

Sx of GI anthrax

Answer 17

Pharyngitis, lymphadenopathy, severe bloody diarrhea, vomiting
(no reported cases in US)

Question 18

Worst case systemic anthrax

Answer 18

Hemorrhagic meningitis

Question 19

Key signs of inhalational anthrax

Answer 19

1. Hilar lymph node infection

2. Mediastinal widening

Question 20

Mechanism of disease

Answer 20

1. Spores inhaled
2. Spores taken up by alveolar/skin/GI macropahges
3. Spores germinate and become encapsulated
4. Vegetative cells form and release toxin
5. Spores disseminate
6. Toxin causes swelling, sepsis, necrosis

Question 21

Incubation period for anthrax

Answer 21

6 weeks (germination of pores in macrophages)

Question 22

What to do if someone is exposed to anthrax?

Answer 22

Give prophylactic cipro for 40 days (incubation period is 6 months)

Question 23

3 key tests for dx anthrax

Answer 23

1. Gram stain (G+)
2. Immunofluorscent Ab stain of CSF
3. Blood smears for boxcar chains

Question 24

Flu vs. inhalational anthrax

Answer 24

Flu won’t have SOB, N/V

Anthrax won’t have rhinorrhea

Question 25

What can also cause mediastinal widening?

Answer 25

1. Histo (no pleural effusion) 2. Cardiac collapse 3. Silicosis, sarcoidosis (chronic not acute)

Question 26

What can also cause skin lesions?

Answer 26

Staph and strep (purulent not necrotic lesions)

Question 27

What things point to anthrax after an act of bioterrorism?

Answer 27

Cluster of people with severe flu-like sx; skin/pneumonic lesions in mail handlers; eschars; WIDENED MEDIASTINUM ON XRAY

Question 28

Tx inhalational anthrax

Answer 28

Cipro or doxy + another Abx (ampicillin) | Must be immediate

Question 29

MAB for anthrax tx

Answer 29

Against B subunit of toxin/protective antigen | Used against Abx-resistant strains

Question 30

How to get rid of anthrax spores?

Answer 30

Boil for 10 min