Actinomycetes

Question 1

Identify the partially-acid-fast positive genera of Actinomycetes.

Answer 1

Nocardia

Rhodococcus

Question 2

Identify the partially-acid-fast negative genera of Actinomycetes.

Answer 2

Streptomyces

Actinomyces

Question 3

List three aerobic actinomycetes.

Answer 3

Nocardia
Rhodococcus
Streptomyces

Question 4

List one anaerobic actinomycetes.

Answer 4

Actinomyces

Question 5

How do we differentiate Nocardia from Actinomyces & streptomyces?

Answer 5

AF Stains
Nocardia red
Actinomyces & streptomyces- blue

Question 6

Nocardia causes infections primarily in what kind of patients?

Answer 6

Immunocompromised patients

Question 7

Which organism causes pulmonary infection in immunocompromised patients?

Answer 7

N. asteroides

Question 8

The cutaneous infections which is usually from traumatic inoculation is caused by_______

Answer 8

N. brasiliensis

Question 9

Cutaneous infections-Traumatic inoculation may develop into _______

Answer 9

Actinomycotic mycetoma

Question 10

List the major illnesses observed in infections related to Nocardia

Answer 10

Immunocompromised patients

• Pulmonary
• dissemination to brain
• cutaneous infections-traumatic inoculation

Question 11

Which organism has high mortality?

Answer 11

Nocardia

Question 12

Describe the microscopic appearance of Nocardia.

Answer 12

Beaded, branching, filamentous GPRs.

Question 13

Describe the plate morphology of Nocardia.

Answer 13

Earthy smell
Slow growing
-often resemble fungi
-has dry, heaped, white to orange, aerial hyphae

Question 14

What is the preferred method used for identifying Nocardia?

Answer 14

HPLC

Question 15

Describe the methods for speciation in identifying Nocardia.

Answer 15

• speciation using hydrolysis of casein, xanthine, tyrosine, or hypoxanthine
  
  • Looking for hydrolysis (+) vs no hydrolysis (-)

Question 16

This organism has negative hydrolysis of casein, xanthine, tyrosine or hypoxanthine.

Answer 16

N. asteroides

Question 17

This organism has casein and tyrosine hydrolysis- Positive

Answer 17

N.brasiliensis

Question 18

Can we differentiate Streptomyces from Nocardia on gram stain?

Answer 18

NO

Question 19

Describe the microscopic appearance of Streptomyces.

Answer 19

GPRs or filamentous, may be beaded

Question 20

This organism is rare in human infections and commercial uses antibiotics, antifungals, and immunosuppressants.

Answer 20

Streptomyces- primarily saprophytes

Question 21

Describe the microscopic appearance of Rhodococcus.

Answer 21

Short, branching gram positive rods