Corynebacterium

Question 1

What is ment by the term palisades when referring to the morphology of Corynebacterium

Answer 1

The term palisades referrs to the bacteria making a row of eachother.

Corynebacterium are the only genus becides acid-fast organisms which display such a unique morphology

WARNING: Corynebacterium also exhibit clumping of bacteria! So they do not have to show this palisades

Question 2

1. What is the species name of the human pathogenic strain of Corynebacterium?
2. T or F the above mentioned pathogen has been eliminated completely in developed countries because of routine vaccination programs (DPT)

Answer 2

1. Corynebacterium diphtheriae
2. False. Routine vaccination programs in developed countries have largely eliminated Corynebacterium diphtheriae however in many developing countries, there may be only 10% of children receiving adequate immunization. As a result, diphtheria causes about 1 million deaths per year.

Question 3

1. Corynebacterium renale is responsible for what diseases in cattle?
2. What diseases in sheep and goats?

Answer 3

1. Cattle: Pyelonephritis, urinary tract infections, cysitis
2. Sheep: Ulcerative posthitis (pizzel rot)

Question 4

Give the general cell morphology/colony characteristics of Corynebacterium renale

Answer 4

Short, stumpy rods, sometimes thicker at one end, non-hemolytic

Question 5

1. Describe the distribution of C. renale
2. What does the distribution tell you about what is nessacary for a cow or sheep to develop disease

Answer 5

1. Distribution of C. renale is widely distributed in normal cattle and sheep in the urethra and prepuce.
2. This tells you that a cow or sheep must have predisposing factors to develop disease

Question 6

1. List a treatment option when treating for a cow with a C. renale infection
2. What about a sheep or goat with a C. renale infection

Answer 6

1. Penicillin!
2. Surgical intervention or application of topical medication

Question 7

List the two biovars present in Corynebacterium pseudotuberculosis

Answer 7

Biovar ovis

Biovar equi

Question 8

List the colony characteristics of Corynebacterium pseudotuberculosis

Answer 8

• Small
• Grayish to yellow to pink
• Fragment easily and can be pushed around the agar surface
• Crumbly (dry) look
• Narrow zone of beta hemolysis

Question 9

1. What would the biochemical results on a urease and a reverse CAMP test show with the organism Corynebacterium pseudotuberculosis
2. What two toxins are exibited by C. pseudotuberculosis and what are there primary effects?

Answer 9

1. Biochemicals: Urease positive, Reverse CAMP (inhibits staphylococcal beta hemolysin)
2. Toxins
   
   • Phospholipase D
     
     • Lethal
     • Dermonecrotic (causing necrosis of the skin)
     • Weak hemolysin
   • Surface lipid
     
     • Toxic for phagocytes

Question 10

List 2 different modes of transmission of C. pseudotuberculosis?

Answer 10

• Transmission
  
  • Present in the soil (can be ingested, enter wound etc… from here)
  • Via wounds (ex. caused by shearing and butting)
  • Abraded buccal mucosa or inhalation
  • Flies and other insects (mechanical vectors)

Question 11

1. What species would you commonly see the C. pseudotuberculosis Biovar ovis in?
2. What does it cause in these species

Answer 11

1. Sheep, goats, and cattle
2. Caseous lymphadenitis in sheep and goats, and abscesses in cattle

Question 12

1. What species would you commonly see the C. pseudotuberculosis Biovar equi in?
2. What does it cause in these species?

Answer 12

1. Equids (horses and donkeys) and cattle
2. In Equids ulcerative lymphangitis, external abscesses in horses in chest area (pigeon fever) & internal abscesses in the liver, lung, kidneys and spleen, and abscesses in cattle

Question 13

What tests can you do to diagnose Corynebacterium pseudotuberculosis?

Answer 13

• Based off clinical signs
• ID on culture
• Synergistic Hemolysis Inhibition test
  
  • Synergizes (makes total effect worst) w/ Rhodococcus equi
  • Possibly useful for internal abscesses

Question 14

How would you treat an zebra with C. pseudotuberculosis

Answer 14

​Drainage of abscesses

Penicillin and other antibiotics will not work because they will be unable to get into lesions

Prevention is KEY: quarantine, drain abscesses, vaccination

Question 15

1. List the clinical signs in a Rhodococcus equi infection in a foal?
2. Human patient with AIDS?

Answer 15

1. Purulent bronchopneumonia, enteritis, and arthritis in foals
2. Pulmonary infection

Question 16

What are the characteristics of colonies of Rhodococcus equi?

Answer 16

• Distinct
• Moist
• Mucoid
• Flowing
• Non-hemolytic

Question 17

Why is the morphology for the species Rhodococcus equi so difficult to identify?

Answer 17

Bacteria range form large rod – cocci depending on where it is cultured from (Cocci more common for media cultures, Lg. rods more common in liquid media)

As well as, bacteria being heavy encapsulation

Question 18

1. What is the biochemical test result you look for in Rhodococcus equis?
2. What is the major antigen associated with R. equis?

Answer 18

1. R. equis will have a very strong CAMP postive result extending down to the far end
2. Antigen: Virulence-associated protein A (VapA)
   
   • Found in 70-80% of isolates that were disease causing

Question 19

1. What is the typical distribution for the Rhodococcus equi bacteria?
2. Your client presents to you a foal with purulent bronchopneumonia, enteritis, and arthritis! When you offer the suggestion of R. equi in your mind you recall that the client mentioned about not having horses in this barn for 10 yrs. Is it possible for the organism to survived for this long?

Answer 19

1. Common commensal of the horse and grows in soil
2. YES! R. equi are very hardy organisms. They can survive in dust for long periods

Question 20

List a typically suceptible horse canidate for a Rhodococcus equi infection? (include age range)

Answer 20

• A foal presenting with CID(combined immunodeficiency disease) or some other underlying stresser such as failure of passive transfer (FPT)
  
  • Common in Arabian foals
• Effects foals ~2-5 months of age

Question 21

In the murine (rat) model of disease the presence of what leads to the killing of Rhodococcus equis?

Answer 21

• The presence or gamma interferon
  
  • Bacterial killing is dependent upon the presence of gamma interferon –> activation of MOs –> production reactive nitrogen & oxygen intermediates –> death of the bacteria

Question 22

In swine Rhodococcus equi may develop secondary too?

Answer 22

• Tuberculosis
• Organism is frequently isolated from LNs of these sows

Question 23

What are the treatment options for a foal with Rhodococcus equi?

Answer 23

Erythromycin + rifampin or long-acting macrolides (e.g. Azithromycin)

• Long-acting macrolides tend to work better

Treatment however has to be early enough in the disease in order to be successful

Question 24

1. The organism Corynebacterium bovis is typically found where?
2. List a likely disease process of this bacteria

Answer 24

1. Tend to be found as commensal organisms on udder
2. Mastitis

Question 25

During a necropsy you identify pyelonephritis on a cow. A student who is working for you asks what possible bacteria can cause this. Based on the bacteria we have covered so far what organism will you choose?

Answer 25

Corynebacterium renale

Question 26

In the image below of a male goat buck what possible bacteria which we have caused this?

Answer 26

Corynebacterium pseudotuberculosis