Brucella, Bordatella, Anaerobic Bacteria

Question 1

What kind of bacteria is Brucella? Also what is it’s shape?

Answer 1

Brucella is a Gram-negative coccobacilli.

Question 2

Comment on Brucella’s characteristics regarding its motility, spore formation, fermentation, oxidation, and whether it grows aerobic or anaerobically?

Answer 2

Brucella is a non-motile, non- sporing, non-fermentative, oxidase positive, AEROBE!!!

Question 3

What type of stain would you use to stain Brucella.

Answer 3

Kosters stain (modified ZN stain)

Question 4

What body system does Brucella primarily target? Due to this what is its cardinal feature?

Answer 4

The male and female reproductive tracts. Brucella causes abortion due to its effects on on the reproduction tract.

Question 5

Is Brucella a Zoonotic pathogen and if so what class?

Answer 5

Yes, category 3 zoonosis.

Question 6

What kind of pathogen is Brucella?

Answer 6

Brucella in an intracellular pathogen that lives within Macrophage cell of the body.

Question 7

Named the different species of Brucella specific for these hosts:

1. Cattle
2. Sheep and Goats
3. Pigs

Answer 7

1. B. abortus
2. B. melitensis
3. B. suis

Question 8

Which species of Brucella are the most virulent for humans (most zoonotic)?

Answer 8

1. B. abortus
2. B. melitensis (most virulent of the 3)
3. B. suis

Question 9

How is Brucella transmitted?

Answer 9

Brucella is transmitted via direct contact by ingestion of unpasteurized milk and cheese. It can also be inhaled due to airborne transmission via abortion, mating, and shedding in milk.

Question 10

Describe the pathogenesis of Brucella in animals…

Answer 10

Once inhaled or ingested, Brucella will penetrate the G.I.T mucosa where it will travel freely or via macrophage to the regional lymph node. Brucella will multiply in the macrophages found in lymph nodes, spleen, liver, bone marrow, sex organs. It allows itself to become phagocytosed by macrophages to allow itself to proliferate and travel systemically to other organs/ tissues causing a Bacteraemia. It will disperse to the Reticuloenthothelial system (Mononuclear phagocyte system), testis, Udder, and Uterus.

Question 11

What main virulence system is Brucella lacking and why?

Answer 11

Brucella lacks adhesion virulence factors such as:
1. Fimbrae
2. Toxins
3. Capsules
4. Type III Secretion System
The reason is because these virulence factors are important for extracellular bacteria whereas Brucella is an intracellular pathogen.

Question 12

What virulence factors contribute to Brucella pathogenesis allowing them to survive and multiply in macrophages?

Answer 12

1. Type IV secretion system which injects effector proteins
2. Brucella, once phagocytosed, inhibits the phagolysosome fusion.
3. Cyclic Beta-1,2 glucan- required for intracellular survival

Brucella does not want to alarm the host upon its arrival to reduce the immune response. This is possible due to the fact the Brucella’s LPS is 1000x less pro inflammatory then E. coli’s LPS. Possibly due to a less toxic Lipid A.

Question 13

What is the preferred carbon source for Brucella and where can it be found?

Answer 13

Brucella has a tropism for ERYTHRITOL which can be found in high concentrations in the placenta of cattle, sheep, goats, and pigs.

Question 14

What tests allow us to screen for Brucella?

Answer 14

Detection of antibody in serum (milk) against Brucella LPS.
Test used are:
1. Milk Ring Test
2. ELISA test- ensures no false positives.
3. Serum Agglutination test- ensures no false positives.

False positives can occur because antibodies cross react with LPS of other bacteria.

Question 15

Comment on Bordatellas characteristics regarding its motility, spore formation, fermentation, oxidation, and whether it grows aerobic or anaerobically?

Answer 15

Bordatella are small gram negative coccobacilli. They are strict aerobes, non-spore forming, most motile. They do not ferment carbohydrates.

Question 16

What body system does Bordatella primarily target? Due to this what is its cardinal feature?

Answer 16

Bordatella primarily infects the respiratory tract causing Kennel cough in dogs, acute pneumonia in cats, and atrophic rhinitis (couple with P. multocida) in pigs.

Question 17

What species of Bordatella infects, dogs, cats, and pigs? What species infects sheep and humans?

Answer 17

1. Bordatella bronchiseptica.

2. Bordatella parapertussis.

Question 18

What agar would B. bronchiseptica grow on? Is this a lactose ferementer?

Answer 18

B. bronchiseptica grows on MacConkey agar as well as sheep blood agar. It It is a non-lactose fermenter. It is reasonable to distinguish B. bronchiseptica from other gram negatives respiratory pathogens via culture because a non lactose fermenter digest the proteins in the medium to produce alkali which turn the colony YELLOW. A lactose fermenter will utilize the lactose in the medium and produce acid, then reducing the pH below 6.8 and forming red/pink colonies.

Question 19

Describe the pathogenesis of B. bronchiseptica.

Answer 19

1. Initial attachment of b.b to ciliated respiratory cells in the URT.
2. B.b becomes tightly adhered to the cilia and produces toxins which paralyze the cilia making them static.
3. Due to the toxins the cilia are lost and accumulation of mucous occurs.

B.b disrupts the mucociliary movement of foreign particles to the surface allowing them to colonize safely in the URT.

Question 20

What virulence factors contribute to bordetellas pathogenicity?

Answer 20

1. Adhesion factors: Fimbrae, Filamentous Hemagglutinin, Pertactin.
2. Toxins: Adenylate cyclase toxin, Tracheal cytotoxin, Dermonecrotic toxin.
3. Type III Secretory System.

Question 21

What are the adhesin virulence factors used by b.b?

Answer 21

1. Fimbrae
2. Filamentous Haemagluttinin
3. Pertactin

Must destroy all 3 for no adhesion to occur.

Question 22

What are the 3 toxins produced in the pathogenesis of B. bronchiseptica?

Answer 22

1. Adenylate cyclase toxin
2. Tracheal Cytotoxin
3. Dermnecrotic toxin

Question 23

Describe the mechanism of adenylate cyclate toxin..

Answer 23

Adenylate cyclase is bound to the RTX toxin (hemolysin leukotoxin). RTX toxin binds to the cell surface and releases adenylate cyclase into the cell activating calmodulin which will increase cAMP. The increase in cAMP will decrease the innate immunity of the pet by decreasing phagocytosis and chemotaxis and a fluid influx into tissues causing edema.

Question 24

Describe the mechanism of tracheal cytotoxin..

Answer 24

Tracheal cytotoxin works with LPS shed from the organisms membrane. They active IL-1 which increases NO in the cell. This increase in NO causes loss of cilia allowing the URT of the animal to be compromised and allowing further infection by other respiratory diseases.

Question 25

Describe how B. bronchiseptica virulence genes are expressed?

Answer 25

BvgA is phosphorylated by BvgS (sensokinase) at 37ºC. Transcription activates the virulence genes.

However if the temp is @ 25ºC, BvgS will not phosphorylate BvgA and no virulence factors will be expressed.

Any mutations of BvgA will not show virulence genes.

Question 26

Describe the pathogenesis of Atrophic Rhinitis and what organisms are involved to allow infection.

Answer 26

Pathogenesis is exactly the same as B. bronchiseptica, however, for Atrophic rhinitis to occur, colonization with toxigenic Pasteurella multocida toxin must occur. (PMT) P. multocida toxin destroys the nasal turbinates, cartilage, and bone allowing deformation to occur.

Question 27

B. bronchiseptica has a live attenuated vaccine that can be administered intranasally. Why is this important in the immunity against it?

Answer 27

the intranasla vaccine is delivered at the point of infection (URT) allowing IgA to spread on the mucosal surface of the respiratory epithelium protecting from adhesions.

Question 28

Where are anaerobic bacteria likely to be found in the body?

Answer 28

Seeing as they require anaerobic conditions, they can grow in the lumen of the large intestines and rumen.
However they can also grow on any mucosal surface (gut, mouth, urogenital tract).

Question 29

If anaerobic bacteria were to be found elsewhere in the body aside from the gut lumen of the Large intestines and the rumen, what would the environment require?

Answer 29

1. Loss of blood suppy (no o2 to tissues)
2. Necrotic conditions (Cell death- no o2)
3. Population of aerobic and facultative anaerobes which reduces the oxygen tension since they require o2. This leaves an anaerobic environment.

Question 30

What kind of bacteria is Anaerobic bacteria and what are significant characteristics of them?

Answer 30

They are gram negative rods and commensals of mucosal surfaces.

• infections are usually polymicrobial
• produce foul smelling lesions (pus)
• opportunist pathogens.

Question 31

Define foot rot as well as explain the bacteria involved.

Answer 31

Foot rot is a polymicrobial infection known as infectious pododermatitis caused by the anaerobic bacteria:

1. dichelobacter nodosus
2. fusobacterium necrophorum
3. arcanobacterium pyogenes (facultative anaerobe)

Question 32

Highlight the pathogenesis of Foot Rot

Answer 32

1. Predisposing conditions: Wetting, trauma
2. Primary colonization: Facultative anaerobes (a. pyogenes.)
3. Secondary colonization: F. necrophorum causes superficial inflammation (dermatitis)
4. Tertiary colonization: Dichelobacter nodosus then causes severe inflammation, ulceration, hoof destruction.
5. Chronic lameness ensues.

Question 33

What kind of bacteria is Dichelobacter nodosus? What are its characteristic features? What disease does it cause? what are its virulence factors?

Answer 33

1. Strict anaerobic gram negative, non sporing rods.
2. Long, Clubbed ends.
3. With the aid of Fusobacterium necrophorum, it causes foot rot in sheep.
4. Virulence factors: Type IV fimbrae, Proteases.

Question 34

What kind of bacteria is Fusobacterium necrophorum? What disease is it associated with? What are its characteristic features? what are its virulence factors?

Answer 34

1. Obligate anaerobe, Gram negative non sporing rods.
2. Pleomorphic rods.
3. Foot rot, amongst others…
4. a. Leukotoxin- damage WBC’s,
   b. Hemolysins
   c. Proteases

Question 35

What diseases does F. necrophorum cause in :
A. Cattle
B. Pig
C. Horses

Answer 35

A. Calf diphtheria, post partum metritis, hepatic abscesses, black spot of teat.

B. Necrotic rhinitis

C. Necrobacillosis of lower limb.

Question 36

What kind of bacteria are these below and what is a major characteristic they share when causing disease?

1. Bacteroides sp,
2. Prevotella sp.
3. Porphyomonas sp.

Answer 36

All are obligate anaerobic gram negative rods.

They are all pyogenic (pus forming) therefore may cause abscesses, and soft tissue infections. The pus is foul smelling.