Bacillus

Question 1

What is the gram test result of bacillus?

Answer 1

Gram positive

Question 2

What shape and arrangement are bacillus?

Answer 2

Rods and in chains or singles

Question 3

True or False. Are most bacillus pathogenic?

Answer 3

No. Theyre mostly non-pathogenic

Question 4

Which bacillus species are pathogenic and what do they cause?

Answer 4

B. anthracis - anthrax
B. cereus - Food poisoning
B. licheniformis - sporadic abortion
B. piliformis - Tyzzer’s disease
B. subtilis - ovine abortion bovine mastitis

Question 5

How does bacillus interact with oxygen?

Answer 5

They are aerobes or facultative anaerobes

Question 6

The majority of bacillus are what?
(Motility, catalase, oxidase)

Answer 6

Motile, catalase +, and oxidase -

Question 7

Which bacillus species are non-motile?

Answer 7

B. anthracis and B. mycoides

Question 8

What is the key feature of Bacillus for survival in harsh conditions

Answer 8

Formation of endospores

Question 9

What are the BSL levels of B. subtilis, B. cereus, and B. anthracis?

Answer 9

B. subtilis = BSL 1 (used for teaching)

B. cereus = BSL 2 (food poisoning)

B. anthracis = BSL 3 (causes anthrax)

Question 10

What is the normal habitat for B. subtilis?

Answer 10

Soil and water

They are also highly tolerant of extreme conditions

Question 11

What are the 3 groups of Bacillus?

Answer 11

B. subtilis group

B. cereus group

B. circulans group

Question 12

How does B. cereus present in cattle, dogs and cats, and humans?

Answer 12

Cattle = mastitis

Dogs and cats = food poisoning

Humans = diarrhea

Question 13

What are the members of the B. cereus group?

Answer 13

B. anthracis

B. cereus

B. mycoides

B. thuringiensis

Question 14

What are the members of the B. subtilis group?

Answer 14

B. subtilis

B. licheniformis

B. pumilis

B. amyloliquifaciens

Question 15

What are the members of the B. circulans group?

Answer 15

B. circulans

B. firmus

B. coagulans

B. lentus

Question 16

How do animals that have died from anthrax present?

Answer 16

Bloated
Putrefy rapidly and do not exhibit rigor mortis
Dark unclotted blood from orifices

Question 17

True or False. You should cut open the carcasses of animals that died from anthrax.

Answer 17

False. Because it facilitates sporulation and risks exposure

Question 18

What are the common targets of B. anthracis?

Answer 18

Ruminants and pigs and horses (herbivores and omnivores)

Question 19

What are the three kinds of human anthrax?

Answer 19

Cutaneous anthrax (malignant pustule)
- lesions can become septicemia

Pulmonary anthrax (wool-sorter’s disease)
- Hemorrhagic pneumonia and meningitis

Intestinal anthrax

Question 20

What are the main virulence factors of B. anthracis?

Answer 20

Two plasmids

Px01 = encodes for toxins to damage tissue and act as immunosuppresants

Px02 = encodes for capsule and prevent phagocytosis

Question 21

What is the tripartite exotoxin that B. anthracis produces?

Answer 21

Protective antigen = allows other toxins to enter

Edema factor = increase cAMP to cause swelling and fluid build up

Lethal factor = disrupts immune signalling to trigger cell death

Question 22

When was the Anthrax vaccine produced and what strain was it based of?

Answer 22

Sterne strain in the 1930s

Question 23

What is the mechanism of action of the Anthrax vaccine?

Answer 23

It uses the Sterne strain which lacks a pXO2 plasmid meaning it cannot produce a capsule.

Question 24

What is the difference between the Sterne strain and the wildtype strain?

Answer 24

The presence of the capsule

Question 25

What are the highly virulent strains of B. anthracis?

Answer 25

Ames and vollum strains

Question 26

How does one control the spread of anthrax?

Answer 26

Vaccination with the Sterne strain Proper disposal of samples Incineration of carcasses Proper disinfection

Question 27

How is anthrax treated?

Answer 27

Penicillin G and other B-lactam antibiotics or Erythromicin as an alternative

Question 28

What are the two forms of B. cereus and how are they obtained?

Answer 28

Emetic form - obtained by ingesting food with toxins and incubate in 1-5 hours Diarrhea form - obtained by ingesting spores and incubate in 1-24 hours

Question 29

What are the virulence factors of B. cereus?

Answer 29

**Cereulide peptide toxins** that can cause emesis (vomiting)

Question 30

When can B. subtilis be pathogenic?

Answer 30

In moments of opportunistic infections especially in immunocompromised individuals

Question 31

What are the primary uses of the B. subtilis group?

Answer 31

For research and production of enzymes and antibiotics

Question 32

What are some useful B. subtilis species?

Answer 32

B. licheniformis - for penicillinase B. polymyxa - for the antibiotic polymyxin B. stearothermophilus - for testing autoclaves

Question 33

How do you collect samples of B. anthracis?

Answer 33

For septicemic form: Swabbing external blood or blood collection For localized form: Swab from cut surface of lymph nodes

Question 34

How do you collect samples of non-anthracis Bacillus species?

Answer 34

From milk or tissues from aborted fetuses

Question 35

How do you identify B. anthracis and non-anthracis?

Answer 35

Culturing non-hemolytic colonies on blood agar in BSL 3 facilities (for B. anthracis) Culturing or direct examination of smears stained with polychromethylene blue (non-anthracis)

Question 36

What is the M'Fadyean's reaction?

Answer 36

It is the staining of the B. anthrax cell with polychrome methylene blue The cell will stain blue while the capsule is stained with a pale pink color

Question 37

How do we differentiate the Bacillus species?

Answer 37

Non-anthracis species are differentiated based on colony characteristics and biochemical tests

Question 38

What is the difference between B. subtilis and B. cereus on a BAP?

Answer 38

B. subtilis have small and mucoid colonies B. cereus have large colonies with wide hemolysis.

Question 39

What is the difference between B. anthracis and B. cereus in terms of motility, capsulation, hemolysis, and resistance to penicillin

Answer 39

B. anthracis - non-motile w/ capsule - non-hemolytic - S (effective) B. cereus - motile w/ no capsule - B-hemolytic - R (resistant)

Question 40

What does B. anthracis look like in BAP?

Answer 40

Dry and wrinkled appearance with fringed-edged colonies (**Medusa-like**)

Question 41

What is the "Strings of Pearls test"

Answer 41

Cell rounding appearance when B. anthracis is exposed to penicillin due to cell wall weakening

Question 42

What is the selective media for B. anthracis?

Answer 42

Polymyxin-Lysozyme-EDTA-Thallous acetate or PLET