Bacillus

Question 1

Bacillus are Gram ___ Large/Small Rods/Cocci that Do/Do Not produce spores

Answer 1

(+), Large, Rods, Do

Question 2

Bacillus are Aerobes/Facultative Anaerobes/Anaerobes

Answer 2

Aerobes and Facultative Anaerobes

Question 3

How do spores play a role in the epidemiology of B. anthracis?

Answer 3

Endospore formation is the most important factor in the persistence and spread of the dz. These can survive in the soil for years. Spores are brought the surface by flooding, excavation, and earthworm activity. Hosts aquire spores via ingestion, inhalation, skin abrasion.

Question 4

State the pathway of B. anthracis from ingestion from herbivore to spores in the environment.

Answer 4

Ingestion -> Germination, multiplication in LN, spleen->Blood Stream all at same time soon before death, bleeding-> Vegetative form in environment-> Spores following O2 exposure

Question 5

What are the three routes that humans are infected with B. anthracis? Which are fatal?

Answer 5

1. Pulmonary (Wool Sorter’s Dz), Gastrointestinal, Cutaneous via lesions (most common)
2. All can be fatal

Question 6

What are the symptoms of B. anthracis infection?

Answer 6

1. Septicemia -> increase in vascular permeability ( so Dz can now perfuse vital organs)
2. Edema/swelling, tissue darkening/necrosis, shock, death (usually found dead)

Question 7

What are the two virulence factors encoded on a plasmid for the pathogenesis for B. anthracis?

Answer 7

1. Poly-D-glutamic acid CAPSULE
2. Complex TOXIN w 3 antigenic components:
   a. Protective antigen-> Creates a pore for the other two factors to bind to to gain entry into cell
   b. Edema factor-> tissue swells, inhibits neutrophils
   c. Lethal factor-> Stimulates macrophages to cause apoptosis which ultimately induces shock

Question 8

How would you diagnose B. anthracis grossly, by culture plate and by slide?

Answer 8

1. Grossly- Bloated, putrified carcass with NO rigor mortis. Bleeding from every orifice
2. Culture Plate- Characteristic ‘Medusa Head’ colonies
3. Slide (Blood Smear)- Blue bacteria surrounded by pink capsule. Must use polychrome methylene blue (McFaydean capsule stain) to stain for Dx. Gram stain is (+) and with holes where spores are (they don’t stain)

Question 9

What are the 5 ways to control B. anthracis.

Answer 9

1. Do NOT open the carcass (will facilitate environmental contamination)
2. Annual vaccination (esp for cattle, live spore capsule but no toxin, NOT attenuated for humans so don’t stick yourself)
3. Chemoprophylaxis and report to authority during outbreaks
4. Incinerate or bury carcasses away from water sources
5. Disinfect contaminated material w 10% formalin or incinerate