27-Nocardia

Question 1

What is the morphology of nocarida?

Answer 1

filamentous, weakly acid-fast bacilli and aerial hyphae on the colony surface which is unique to only Nocardia.

Question 2

What type of media should you use for Nocardia?

Answer 2

buffered charcoal yeast extract [BCYE] agar

Question 3

What type of pt’s are at risk for Nocardia infections?

Answer 3

Patients at greatest risk for disease are those with T-cell deficiencies produced by disease (e.g., leukemia, AIDS) or immunosuppressive therapy (e.g., corticosteroids for renal, cardiac, bone marrow transplants)

Question 4

What are the 4 clinical presentations of Nocardia infections?

Answer 4

1. Mycetoma
2. Lymphocutaneous disease
3. Superficial skin infection with abscess formation or cellulitis
4. Secondary to bronchopulmonary infection

Question 5

What are the VF’s of Nocardia?

Answer 5

catalase and superoxide dismutase

Question 6

What are the 3 ways Nocardia can survive and replicate in macrophages?

Answer 6

1. Preventing fusion of the phagosome-lysosome (mediated by cord factor)
2. Preventing acidification of the phagosome (by an undefined mechanism), and
3. Avoiding acid phosphatase-mediated killing by metabolic utilization of the enzyme as a carbon source