Actinobacteria

Question 1

Actinomyces spp Characteristic

Answer 1

• gram + that are non-motile
• Non-spore forming & often filamentous

Question 2

Actinomyces spp type of pathogen

Answer 2

• Typically commensal organisms
  
  • Can cause infection when there is an injury, trauma or immunosuppression, allowing the bacteria to localise & cause wound infection
    generally associated with secondary wound infection or abscesses

Question 3

O2 requirement Actinomyces spp

Answer 3

Some species are facultative anaerobes or obligate anaerobes

Question 4

Actinomyces bovis causes?

Answer 4

primarily cause lumpy jaw in cattle

Question 5

Actinomyces bovis in humans

Answer 5

• commensal in humans
  
  • Can cause lumpy jaw in humans following inoculation into the jaw after injury or trauma
• Not considered zoonotic

Question 6

Actinomyces denticolens

Answer 6

• known to cause soft tissue abscess in horses
• often linked to dermal trauma or reintroduction of the strain

Question 7

Characteristics of Nocardia spp.

Answer 7

• gram +
• Often filamentous, branching bacteria
• Partially acid fast, meaning a modified Ziehl Neelson test can be used for diagnosis
• soil saprophyte

Question 8

Nocardia asteroides in cattle

Answer 8

• Causes mastitis in cattle
  
  • specifically a chronic fibrinous mastitis
    
    • Which is often resistant to many antimicrobials (inherent resistance)
    • Can lead to the loss a udder quarter or the culling of the animal

Question 9

Nocardia asteroides in dogs

Answer 9

• a common cause of pyothorax & local wound infections, often secondary to bite wounds, other acquired wounds, inhalation or ingestion
  
  • can also periodontitis

Question 10

Characteristics of Trueperella pyogenes

Answer 10

• acts as secondary, opportunistic invader
• Often found in mixed infections
• Comensal & soil bacterium

Question 11

Manifestation of Trueperella pyogenes infection

Answer 11

• Infections typically manifest when there is a trauma, immunosuppression or other existing infections
• Notably pus-forming & can create granulomas in various body parts
  Occur when soil bacteria gain access to sterile sites, often facilitated by trauma or compromised immune system

Question 12

Infections caused by Trueperella pyogenes

Answer 12

Mastitis, Arthritis, Pneumonia, Pyaemia, Local abscesses, Metritis, liver abscessation, umbilical infection, endocarditis

Question 13

Characteristics of Actinobaculum suis

Answer 13

• gram +
• Non motile
• Non spore forming
• Often filamentous

Question 14

Diseases caused by Actinobaculum suis

Answer 14

Causes porcine cystitis, pyelonephritis & mastitis

Question 15

Characteristics of Dermatophilus congolensis

Answer 15

• gram +, filamentous rod that produces zoospores
• has a distinctive “train-track like” appearance under the microscope
• Skin-loving organism
• Commensal of the skin
• Zoospores are resilient & can survive for up to 3 years

Question 16

Primary disease of Dermatophilus congolensis

Answer 16

Lumpy wool or mycotic dermatitis in sheep

Question 17

Aetiology of mycotic dermatitis

Answer 17

Normally present on the skin, the dormant zoospores are activated by moisture & temperature when there is trauma & persistent wetting

Upon activation, the zoospores germinate into filamentous organisms that then proliferates & attach the skin

If animal does not experience excessive wetting, trauma & high temperatures, the zoospores should not germinate & will not lead to a major issue

Question 18

Characteristics of mycotic dermatitis

Answer 18

• infection of skin, followed by scab formation
• Characteristically, hard abscesses lift from the skin as the infection grows, giving the lumpy wool appearance

Question 19

haemolytic pattern of dermatophilus congolensis on blood agar

Answer 19

• Organism can be cultured on blood agar
  
  • grows with a-haemolytic zone

Question 20

Impact & diagnosis of dermatophilus congolensis

Answer 20

• ead to loss of animal condition
  
  • infection of skin followed by scab formation
• Reduced skin values, reduced wool value
• Attracts flies, fly strike
• Hard scab masses lift from the skin with the fleece
• A skin scab is required for diagnosis