Bacillus

Question 1

What are the 3 species of Bacillus of veterinary importance?

Answer 1

1. B. anthracis
2. B. cereus
3. B. licheniformis

Question 2

How does Bacillus stain? What is their morphology?

Answer 2

Gram positive

large rods in pairs or long chains

Question 3

What respiration does Bacillus undergo? What 4 things makes them highly resistant in the environment?

Answer 3

aerobes or facultative anaerobes

1. can form endospores that are able to survive more than 50 years
2. resists desiccation
3. resistant to high temperatures
4. resistant to chemical disinfectants

Question 4

Is Bacillus commensal?

Answer 4

no - widely distributed in the environment

Question 5

How does Bacillus respond to motility, catalase, and oxidase tests?

Answer 5

positive
positive
negative

Question 6

Why is Bacillus catalase positive?

Answer 6

contains cytochrome oxidase or indophenol oxidase that are able to catalyze the transport of electrons from donor compounds to electron acceptors

Question 7

How does B. anthracis, B.cereus, and B. licheniform compare in blood agar growth?

Answer 7

B. anthracis - flat, grayish appearance (medusa head at the edge of the colony; NO hemolysis

B. cereus - colonies similar to B. anthracis, with a greenish tinge; hemolysis around colonies

B. licheniform - dull, rough, wrinkled, and strongly adherent to agar

Question 8

Answer 8

B. anthracis
(medusa head)

Question 9

Answer 9

B. cereus
(hemolysis)

Question 10

Answer 10

B. lichenform
(dull, rough, wrinkled)

Question 11

What clinical manifestations are caused by B. anthracis in cattle/sheep, pigs, horses, and humans?

Answer 11

CATTLE/SHEEP: fatal peracute/acute septicemia anthrax
PIGS: subacute anthrax with edematous swelling in pharyngeal region
HORSES: subacute anthrax with localized edema; septicemia with colic and enteritis
HUMANS: skin, pulmonary, intestinal anthrax

Question 12

What are the 2 most susceptible animals to B. cereus infection? What are the clinical manifestations?

Answer 12

1. CATTLE: mastitis
2. HUMANS: food poisoning, eye infections

Question 13

What are the most susceptible animals to B. lichenformis infection? What is the clinical manifestation?

Answer 13

CATTLE and SHEEP - sporadic abortion

Question 14

What events lead up to the entrance of Bacillus into its host?

Answer 14

• endospores are widely distributed in the environment
• thrive in alkaline soils rich in Ca and N cause the spores to reactivate
• causes the contamination pastures and buried carcasses with the spores
• spores are either ingested, inhaled, or enter through the skin

Question 15

What allows Bacillus to be resistant to phagocytosis?

Answer 15

capsule

Question 16

What are the main 3 toxins that contribute to Bacillus virulence?

Answer 16

1. protective antigen (binding moiety)
2. edema factor - targets neutrophils
3. lethal factor - targets macrophages, DC, and epithelial/endothelial cells

Question 17

What are the 5 main clinical signs of Bacillus infection? What animals are most susceptible?

Answer 17

1. fever
2. depression
3. congested mucosa
4. petechiae
5. abortion

cattle and sheep

Question 18

What are 5 characteristic lesions of Bacillus infection? Which one is characteristic in cattle?

Answer 18

1. rapid bloating
2. incomplete rigor mortis
3. ecchymotic hemorrhages and edema
4. dark, unclotted blood and blood-stained fluids in cavities
5. extremely large and soft spleen***

Question 19

What are the 5 ways Bacillus infection is diagnosed? What is avoided?

Answer 19

1. presence of unclotted blood in mouth, nostrils, and anus
2. blood sample/fluids —> Gram staining
3. bacterial culture —> blood agar
4. PCR
5. Ascoli test, precipitation, gel diffusion

opening the carcasses

Question 20

What are the 2 treatments for Bacillus infection?

Answer 20

1. penicillin
2. oxytetracyclin

Question 21

How is Bacillus infection controlled in endemic regions?

Answer 21

annual vaccinations —> Sterne strain live vaccine where the spores convert in non-encapsulated avirulent vegetative organisms

Question 22

In what 5 ways is Bacillus infection controlled in non-endemic regions?

Answer 22

1. avoid movement of animals
2. PPE
3. foot baths (formalin + peracetic acid)
4. immediate disposal of carcasses
5. lock all buildings and fumigate with formaldehyde