Gram Positive Rods (part 2)

Question 1

Habitat of Erysipelothrix rhusiopathiae

Answer 1

fish, shellfish, birds pigs

Question 2

Erysipelothrix rhusiopathiae

- Gram stain

Answer 2

GPR’s short, long, filamentous

Question 3

Erysipelothrix rhusiopathiae

- plate morphology

Answer 3

usually small, alpha hemolytic (resembles alpha streptococci)

Question 4

Erysipelothrix rhusiopathiae

• catalase reaction
• KIA reaction
• H2S reaction

Answer 4

• negative
• A/A
• H2S pos

Question 5

Arcanobacterium haemolyticum

- what disease does it cause

Answer 5

pharyngitis in young adults

Question 6

Arcanobacterium haemolyticum

- hemolysis

Answer 6

Beta (resembles beta strep)

Question 7

Arcanobacterium haemolyticum

- catalase reaction

Answer 7

negative

Question 8

Arcanobacterium haemolyticum

- gram stain

Answer 8

(differentiated from strep by Gram stain)

- GPR pleomorphic, may be rudimentary branching

Question 9

Family of several genera that produce GPR’s that often branch

Answer 9

Actinomycetes

Question 10

Name the AEROBIC Actinomycetes we discussed in class

Answer 10

Nocardia
Rhodococcus
Streptomyces

Question 11

Nocardia

• Gram stain
• Is it acid fast?

Answer 11

• beaded GPR

- Partially Acid-Fast!!!!!!

Question 12

In what people do Nocardia infections primarily occur

Answer 12

immunocompromised patients

Question 13

Streptomyces

• Gram stain
• Acid fast?

Answer 13

• GPR’s or filamentous, may be beaded

- Modified Acid-fast NEGATIVE

Question 14

What are the colors for positive and negative acid fast tests?

Answer 14

Stain red (partially positive) 
Stain blue (negative)

Question 15

How do you differentiate Streptomyces from Nocardia?

Answer 15

CANT be differentiated based on Gram stain but CAN be from modified acid-fast test

Question 16

Rhodococcus equi

• Disease in what type of people?
• Characteristic of this disease

Answer 16

Found in immunocompromised patients (esp. HIV)

- There are often multiple relapses because treatment needs to be 4-6 months to get rid of disease

Question 17

Rhodococcus equi

- how does it look on SBA

Answer 17

• salmon-pink colonies afar 24-48 hours