Gram Positive Bacteria

Question 1

Name three types of canine pyoderma caused by Staphylococcus pseudointermedius.

Answer 1

1. Superficial pyoderma
2. Pustular pyoderma
3. Deep pyoderma

Question 2

Name and describe four Staphylococcus spp. virulence factors.

Answer 2

1. Capsule/ slime layer
2. Adhesions
3. Toxins & Super antigens
4. Protein A

Question 3

Name the bacterial agent that causes Greasy Pig Disease.

Answer 3

Staphylococcus hyicus

Question 4

Describe the pathogenesis of staphylococcus hyicus

Answer 4

• Causes exudative non-pruritic dermatitis in young pigs (up to 3 months of age)
  Extremely contagious

Question 5

Name the genus and species causing canine and feline dermatitis.

Answer 5

Staphylococcus pseudointermedius

Question 6

Using one bacterial example, describe the mechanism of action of superantigens and how they induce an inflammatory response.

Answer 6

Superantigens bind to the MHC class II molecules of antigen-presenting cells and T cells (in a non-antigen-specific manner), which lead to the massive release of cytokines that subsequently bypasses the normal antigen-presenting pathway. This process signals the release of mass inflammatory mediators which cause havoc and make it harder for the immune system to hone in on the specific pathogen.

e.g. Streptococcus canis causing STSS

Question 7

Name and describe four Streptococcus spp. virulence factors.

Answer 7

1. Capsule
2. Cell wall proteins (M proteins)
3. Adhesions
4. Toxins

Question 8

Name the aetiological agent and describe the treatment and control of equine strangles.

Answer 8

Streptococcus equi subsp. equi
Treatment:
- Compress of lymphadenopathy

Question 9

Describe the pathogenesis of listeriosis

Question 10

What bacterial agent is “Silage eye” associated with?

Answer 10

Listeria monocytogenes

Question 11

What gross & histopathologic lesions might you expect to see in a case of listeriosis?

hint: blood, liver, brain

Answer 11

1. Focal hepatitis (white spots on liver)
2. Peri-vascular cuffing with micro-abscessation (brain smear - medulla and brain stem)

Question 12

Name the toxin linked to Greasy Pig Disease.

Answer 12

Exfoliative toxins

Staphylococcus hyicus

Question 13

Name the bacterial agent causing caseous lymphadenitis in sheep.

Answer 13

Corynebacterium pseudotuberculosis

Question 14

Name the bacterial agent causing Pizzle Rot in cattle or Ovine Posthitis (Pizzle Rot) in sheep.

Answer 14

Corynebacterium renale

Question 15

Name the bacterial agent which causes diphtheria in humans

Answer 15

Corynebacterium diphtheriae

Question 16

Describe the gross findings on necropsy of a sheep with caseous lymphadenitis.

Answer 16

1. Encapsulated caseous material found in lymph nodes (characteristic ‘onion ring’ cross section apperance)
2. Lung abscessation
3. Liver abscessation

Question 17

List and describe three virrulence factors of Corynebacterium

Answer 17

1. Cell wall lipid
2. phospholipase D (PLD)
3. Serum protease/s

Question 18

With regard to corynebacterium pseudotuberculosis list and describe the virrulence factors that are required for abscessation in the viscera to occur.

Answer 18

1. Phospholipase D (PLD)
2. Serum protease/s

If PLD and or/proteases are absent, only local abscesses are formed

Question 19

List the treatment, control and prevention strategies for Caseous lymphadenitis in sheep.

Answer 19

Treatment:
1. Corynebacterium suseptible to Penecillin’s in vitro, however abscesses limit penetration of the antimicrobial, rendering it reletively ineffective in practice.
2. Surgery - surgical excision/ drainage of caseous lymph nodes. Care must be taken however to ensure bacteria is not then spread in the environment. Treatment is limited as abscesses often reoccur post surgical intervention.
3. Culling of infected sheep.

Control & Prevention:
1. Vaccination - Sheep vaccinated 4-6 weeks prior to sheering (preventing opportunistic infection from knicks when sheering)
2. Culling of infected sheep
3.Imporved sanitation in sheering sheds and on farm in general
4.Reduced stocking densities and close contact between sheep
5.Avoid wet diping where possible
6.Sheer, dip and handle young sheep first (more susceptible to infection)

Question 20

Name the bacterial agent causing ‘blackleg’

Answer 20

Clostridium chauvoei

Question 21

Name the bacterial agent that causes Gas gangrene

Answer 21

Clostridium perfringens Type A

Question 22

Name the bacterial agent that causes ‘Braxy’ in cattle.

Answer 22

Clostridium septicum

Question 23

Name the bacterial agent causing ‘Blacks disease’.

Answer 23

Clostridium novyi

Question 24

Name two bacterial agents that may cause polyarthritis in pigs.

Answer 24

Mycoplasma hyorhinus
Mycoplasma Hyosynoviae

Question 25

Does Mycoplasma hyosynoviae cause polyarthritis in younger or older pigs?

Answer 25

Older, often seen in pigs aged 10-30 weeks old.

Question 26

How would you treat a case of discospondylysis caused by Aspergillus fumigatus?

Answer 26

1. Treatment of disseminated Aspergillosis fumigatus is complicated, time-consuming, and can often be expensive.
2. Antifungal treatment is available (for example, fluconazole), however, requires long-term use (months – years).
3. Pain medication (NSAIDs or opioids)
4. Restricted exercise and physical activity and bed/ cage rest
5. Euthanasia is a treatment option in severe cases (neurological signs and no resolution following antifungal & supportive treatment).

Question 27

How would you treat a case of discospondylysis caused by Staphylococcus pseudointermedius?

Answer 27

1. S. pseudointermedius is an opportunistic infection, therefore investigate the potential underlying cause of primary infection (surgical wound, surgical bone implant wound).
2. Deep infection (as it has disseminated to the bone), therefore long and high dose AMs are required to treat the infection.
3. Perform culture and sensitivity to determine if it is a MRSP and determine which antimicrobial is most likely to be effective.
4. If not MRSP, systemic antibiotics likely – Cephalosporins, beta-lactamase resistant penicillins (long course –> 3-12 weeks)
5. Pain medication (NSAIDs or opioids)
6. Restricted exercise and physical activity and bed/cage rest
7. Euthanasia is a treatment option in severe cases (neurological signs and no resolution following AM & supportive treatment)

Question 28

What is the aetiological agent that caused Lumpy wool (sheep) & rain rot/ rain scald (horses)?

Answer 28

Dermatophilis congolensis

Question 29

Name the aetiological agent causing Johne’s disease?

Answer 29

Mycobacterium avium subsp paratuberculosis

Question 30

Name the atieological agent causing ringworm in horses.

Answer 30

Trichophyton equinum

Question 31

Name the atieological agent causing ringworm in cattle.

Answer 31

*Thricophyton verrucosum *

Question 32

Name the agent causing swine dysentry

Answer 32

Brachyspira hyodysenteriae