Anthrax: Bacillus anthracis

Question 1

Classify Bacillus anthracis:

Answer 1

Gram +
Facultative anaerobe
Non-motile
Spore forming
Bacillus (rod shaped)

Question 2

How does B. anthracis appear under a microscope?

Answer 2

Boxcar shaped

“BoX car in B. anthraX”

Question 3

What are the two primary virulence factors for B. anthracis?

Answer 3

1) Anti-phagocytic non-antigenic capsule (poly-d-glutamic acid)
2) AB Toxin (Anthrax Toxin)
* note, the spore is the transmissible form of infectious anthrax

Question 4

Describe the subunits of AB Toxin (Anthrax Toxin)?

Answer 4

B = Protective antigen (binds receptors and allows endocytosis)

A has two different parts
A1 = Edema Factor (calmodulin activated adenylate cyclase) –> increases cAMP in a cell –> causes swelling

A2 = Lethal Factor (metalloprotease) –> cleaves host cell MAP kinases –> disrupt cell signalling (kills it) + stop innate immune response

Question 5

What is the most important reservoir of anthrax?

Answer 5

Domesticated farm animals, primarily cows

Question 6

What two diseases does anthrax cause?

Answer 6

1) Cutaneous anthrax

2) Inhalational antrax

Question 7

Name this anthrax disease: Painless, itchy, necrotic papule (aka eschar) surrounded by a local area of severe swelling, possibly painful lymphadenopathy.

Answer 7

Cutaneous anthrax

–acquired through cuts/scratches of the skin

Question 8

Name this anthrax disease: Initial flu-like symptoms, followed by severe SOB and chest pain. Untreated, it becomes a hemorrhagic meningitis.

Answer 8

Inhalational anthrax

–acquired by breathing 1-5 micrometer sized spores

Question 9

Is inhalational anthrax classified as a pneumonia?

Answer 9

NO.

The spores vegetate in macrophage within the mediastinal and hilar lymph nodes, no the lung parenchyma.

Question 10

What is inhalational anthrax also called?

Answer 10

Hemorrhagic mediastinitis with pleural effusion.

Question 11

If farmers mess with cows all the time, why don’t they get anthrax more often?

Answer 11

The spores are “sticky” and attach to dirt particles in the air. Therefore, they rarely reach the mucous membranes in an infectious form.

Question 12

How do you differentiate anthrax from the flu?

Answer 12

1) Anthrax won’t have rhinorrhea (runny nose)
2) Flu doesn’t cause severe SOB, nausea and vomiting
3) Mediastinal widening on a CXR

Question 13

How do you diagnose anthrax?

Answer 13

1) Differentiate from flu (also, there would be a suspicious cluster of severe flu-like illness)
2) Immunofluorescent Ab stain CSF and
Blood smear for G+ boxcars
3) widened mediastinum on CXR

Question 14

How do you treat/prevent anthrax in a person who might have been exposed?

Answer 14

1) 40 days of ciprofloxacin/doxycyclin IV + ampicillin (this bug can take 6 weeks to incubate, so you must treat it for a long time)
2) Vaccine