Erysipelothrix and Rhodococcus

Question 1

What is the gram reaction of Rhodococcus and Erysipelothrix?

Answer 1

Gram positive

Question 2

Which Erysipelothrix species is responsible for causing erysipelas?

Answer 2

E. rhusiopathiae

Question 3

Which Erysipelothrix species was formerly recognized as E. rhusiopathiae?

Answer 3

E. tonsillarum

Question 4

What are the two morphologies of E. rhusiopathiae?

Answer 4

Acute morphology
- smooth colonies
- slender rods

Chronic morphology
- rough colonies
- short filaments

Question 5

What is the usual habitat of E. rhusiopathiae?

Answer 5

Swine is the primary reservoir
Found in tonsils, digestive tract
Found in environment (soil)

Question 6

How is E. rhusiopathiae aqcuired?

Answer 6

Ingestion of fecally-contaminated material

Question 7

What are the virulence factors of E. rhusiopathiae?

Answer 7

Capsule (protection from phagocytosis)

Neuraminidase (for adherence and penetration)

Hyaluronidase (invasion and dissemination)

Question 8

How does the acute form of swine erysipelas present itself?

Answer 8

Septicaemia and skin lesions (diamond skin)

Question 9

What does the subacute form swine erysipelas present itself as?

Answer 9

Mid septicaemia and skin lesions

Question 10

What is the chronic form of swine erysipelas?

Answer 10

Endocarditis
Polyarthritis
Skin lesions

Question 11

How is E. rhusiopathiae treated?

Answer 11

Penicillin
Alternatively: Ampicillin and Ceftiofur

Question 12

How is E. rhusiopathiae prevented?

Answer 12

Vaccination
Sanitation
Nutrition

Question 13

What is the common manifestation of erysipeloid?

Answer 13

Acute localized cellulitis on the hands and fingers

Rarely endocarditis, arthritis, and acute septicemic disease

Question 14

How is erysipeloid acquired in humans?

Answer 14

As an occupational hazard (handlers not properly cleaning hands after handling or random fecal matter spread)

Question 15

What methods are used to diagnose erysipeloid infections?

Answer 15

Culturing a biopsy specimen or with PCR testing

Question 16

How are samples of E. rhusiopathiae collected?

Answer 16

From necropsy examination of the visceral organs like liver, spleen, kidney

Culturing swabs from the joints

Question 17

What methods/medium/tests are used to diagnose E. rhusiopathiae in the lab?

Answer 17

Blood agar and biochemical test

PCR to identify
Using enrichment broth for cultivation

Question 18

What is the hemolytic reaction of E. rhusiopathiae on blood agar plate?

Answer 18

Gamma or weakly alpha

Question 19

Why is E. rhusiopathiae gamma or weakly alpha hemolytic?

Answer 19

Because at 24 hrs it shows non-hemolytic colonies
but at 48 hrs a zone of alpha hemolysis exists

Question 20

What is the TSI reaction of E. rhusiopathiae and E. tonsillarum?

Answer 20

Formation of a thin black line along the inoculation stab (H2S positve)

Question 21

How does one differ from E. rhusiopathiae and E. tonsillarum?

Answer 21

CHO Fermentation test

They are identical except in their ability to ferment sucrose

Question 22

What is the one Rhodococcus species with the most significance to veterinary medicine?

Answer 22

R. equi

Question 23

What is the appearance of R. equi?

Answer 23

Coccus or rods (coccobacilli)

Question 24

What was R. equi formerly known as?

Answer 24

Corynebacterium equi

Question 25

Although R. equi is gram positive it also has a reaction with the acid-fast test, what is its reaction?

Answer 25

Weakly acid fast/Partially acid fast

Question 26

True or False. True to its name, R. equi is an equine only microbe.

Answer 26

False. R. equi is an emerging human opportunistic pathogen

Question 27

What is the usual habitat of R. equi?

Answer 27

In soil, manure contaminated soil

Question 28

R. equi is a pathogen of major importance to

Answer 28

equine **breeding activities**

Question 29

What is the most important virulence factor of R. equi that lets it cause disease?

Answer 29

The presence of a **plasmid with vapA gene so it can interfere with phagolysosome formation/function**

Question 30

How does R. equi present in foals vs older horses?

Answer 30

In foals it is a **suppurative pyogranulomatous bronchopneumonia** but in In adults **abscessation** is present

Question 31

How is R. equi transmitted?

Answer 31

Via **inhalation of fecally-contaminated dust** from foals and older horses

Question 32

How is R. equi treated?

Answer 32

Antimicrobials like **Rifampin and the macrolide drug**

Question 33

How are samples of R. equi collected and what technique is used to identify them?

Answer 33

Collected from tracheal aspirates and pus Then they culture or PCR to detect R. equi

Question 34

On what media does R. equi grow?

Answer 34

On **Non-enriched media** where it develops mucoid salmon-pink colonies *Blood agar* *Nutrient agar* *Pigment enhancing medium*

Question 35

What is the characteristic appearance of R. equi on agar plates?

Answer 35

The formation of the mucoid "milk drop" appearance in 48 hours

Question 36

True or False. R. equi is taxonomically related to Nocardia and Mycobacterium.

Answer 36

True they are related

Question 37

Which techniques are required to acid fast R. equi?

Answer 37

Ziehl-Neelse and Kinyoun techniques

Question 38

How does R. equi react in a CAMP test with S. aureus and C. pseudotuberculosis?

Answer 38

Since it produces **phospholipases or "Equi factors"** it can **enhance the hemolytic activities** of *S. aureus*' B-toxin and *C. pseudotuberculosis*

Question 39

Why is the CAMP Test a quick presumptive test for C. pseudotuberculosis, R. equi, and C. renale?

Answer 39

Because both **R. equi and C. renale have an enhancing effect on the Staph beta-hemolysin**

Question 40

What is the reaction of R. equi and C. pseudotuberculosis in a CAMP test by themselves?

Answer 40

Synergistic hemolysis