Gram-Positive Rods

Question 1

Erisypelothrix (GP-Rod)

Answer 1

25 serotypes (1 & 2 most common). In pigs, cause systemic bacterial infection = rhomboidal skin lesions. Chronic = endocarditis, athritis. Zoonotic.

Question 2

Listeria monocytogenes (GP-Rod)

Answer 2

Haemolytic on blood agar. Causes Listeriosis, which is Zoonotic. Can cause abortion, meningioencephalitis.

Question 3

Arcanobacterium (Actinomyces) pyogenes (GP-Rod)

Answer 3

B-haemolytic. Common opportunistic pathogen of ruminanats and pigs. Can cause absesses, and summer mastitis.

Question 4

Actinomyces (GP-Rod)

Answer 4

Filamentous, Branching. Important species: A. viscosus - canine thoracic lesions, A. bovis - Lumpy Jaw in cattle/sheep.

Question 5

Corynebacterium (GP-Rod)

Answer 5

C. renale, C. pilosum, C. cystitidus. Causes cystitis and pyelonephritis in Cattle, Abscesses in Kidney.

Question 6

Dermatophilus (GP-Rod)

Answer 6

D. congolensis causes Mud-Fever in horses (skin disease associated with wet conditions)

Question 7

Mycobacterium are… Which important species? (3)

Answer 7

GP Rods, which are acid fast. Round ended, strictly aerobic. Not stained by gram stain.

Question 8

Which important Mycobacterium species? (3)

Answer 8

M. bovis (TB), M. paratuberculosis (Johne’s Disease), M. avium (Avian TB)

Question 9

Which stain is used to detect Mycobacterium? Why?

Answer 9

Ziehl-Neelsen Stain. - Tissues and bacteria appear blue, Acid fast bacteria appear red. Difficult to stain with Gram stain due to mycolic acid.

Question 10

How is Bovine Tuberculosis diagnosed?

Answer 10

Intradermal Tuberculin Test.

Question 11

How does the Tuberculin test work?

Answer 11

Injection of small amount of antigenic extra of M. bovis. If infected, cattle will show a localised swelling of the skin a few days later.