Genus Actinomyces, Dermatophilus, and Nocardia

Question 1

What are the three main species of Actinomyces which we talked about?

Answer 1

Actinomyces bovis

Actinomyces viscosus

Actinomyces suis

Actinomyces israelii (Not main just other)

Question 2

What is the main species of Nocardia which we talked about?

Answer 2

Nocardia asteroids

Nocardia branziliensis (Not main just other)

Question 3

What is the only species of Dermatophilus which we talked about?

Answer 3

Dermatophilus congolensis

Question 4

1. What is the clinical sign in a cow with Actinomyces bovis
2. What about a horse?

Answer 4

1. Lumpy jaw in cattle
2. Fistulous withers and poll evil in horses

Question 5

List the morphologic features which we covered of a Actinomyces bovis bacteria

Answer 5

• Gram positive
• Filamentous or short rods which appear as cocci
• Extreme microaerophile
  
  • Can’t grow in the lab

Question 6

How does the bacteria Actinomyces bovis, enter a host?

Answer 6

Entry of the organism through dental alveoli or trauma (pieces of wire or wood) to the gums or oral mucosa.

Question 7

1. What mechanism of the immunsystem attacks Actinomyces bovis?
2. How can one treat an infection of Actinomyces bovis?

Answer 7

1. Immunity induced by CMI, lesions are progressive
2. Treatments generally do not help in chronic infections.
   
   1. One can try surgical edition or IV injection or sodium iodide

Question 8

Where does Actinomyces viscosus preferentially invade on dogs?

Answer 8

Invades wounds in the head and neck area

Question 9

1. Lesions to the thorax of dogs caused by Actinomyces viscosus will result in what type of lesion?
2. How does one go about treating Actinomyces viscosus?

Answer 9

1. Pyothorax
2. Treatment is by debride, antibiotics, generally is localized (tends not to metastasize)

Question 10

1. What does clincical signs do Actinomyces suis cause?
2. What species does Actinomyces israelii effect?

Answer 10

1. Mammary gland lesions granuloma, little abscessation in the mammary gland
2. Humans

Question 11

1. List the clinical signs associated with Nocardia asteroids in dogs and cats
2. What about in cows?
3. Why does Nocardia asteroids partially stain acid fast?

Answer 11

1. Suppurative thoracic, subcutaneous lesions and granulomatous infections
2. Mastitis
3. Nocardia produces nocardic acids which are similar to the mycolic acids of mycobacteria (meaning they have a high lipid content of their cell walls)

Question 12

1. What is the pathogenesis of Nocardia asteroids
2. T or F Nocardia asteroids tends to metastasize

Answer 12

1. Immune suppression (or traumatic introduction) –> Pulmonary infections –> Pyothorax (from bite wounds)
2. True. Nocardia asteroids is very infectous and tends to spread

Question 13

Where can Nocardia branziliensis be isolated from?

Answer 13

Can be isolated from dogs or humans

This is all the information Dr. Griffith gives about this species in his note and powerpoint

Question 14

1. What disease does the organism Dermatophilus congolensis cause?
2. What does it cause?

Answer 14

1. Dermatophilosis
2. Exudative dermatitis

Question 15

List the unique aspect of the Dermatophilus congolensis organism?

Answer 15

The life cycle: contains motile zoospores (Which are released from the filaments, these grow and form a germ tube and eventually new filaments)

Question 16

List the distribution of Dermatophilus congolensis?

Answer 16

Distribution is worldwide in the soil

More common in tropical environments but can survive winter months.

Disease seems to be most common a problem in horses stabled inside in the winter.

Question 17

What is the comon name for the disease of Dermatophilus congolensis dermatophilosis?

Answer 17

“rain rot”

Question 18

What occurs in the disease process of Dermatophilosis “rain rot”? (start at what predisposes the bacteria from invading

Answer 18

Pathogenesis

Trauma (such as tick bites)

Then serum and cell debris form into large, thick scabs

These scabs can fall off/be removed and will have an raw underside

Question 19

How does one diagnose and treat for Dermatophilosis “rain rot”?

Answer 19

Diagnosis

Smear of exudate à dry à preform a giemsa stain

Treatment

Topicals

Penicillin