Module 6: Listeria (Wittum)

Question 1

List the multiple species of Listeria:

Answer 1

1. Listeria monocytogenes (LM)
2. L. innocua
3. L. ivanovii
4. L. seeligeri
5. L. welshimeri

Question 2

What are the microbiological characteristics of Listeria?

Answer 2

• Gram-positive bacillus
• Beta-hemolytic
• SURVIVES and PROLIFERATES at 4C
  - That is refrigeration temperature

Question 3

(T/F) For Listeria, exposure dose is important

Answer 3

True

Question 4

Which Listeria serotypes are most commonly associated with human disease?

Answer 4

1a, 1b, 4b

Question 5

_________________ is evolving as a tool to differentiate between pathogenic and non-pathogenic strains

Answer 5

Microarray analysis

Question 6

(T/F) Most food contamination of Listeria originates from the processing environment, not directly from animals

Answer 6

True

Question 6

(T/F) Most food contamination of Listeria originates from the processing environment, not directly from animals

Answer 6

True

Question 7

(T/F) Zoonotic transmission of Listeria can occur but is relatively rare

Answer 7

True

Question 8

How does Listeria most commonly contaminate food products available at grocery stores?

Answer 8

Contamination of food products by Listeria present in the food processing environment

Question 9

What are the important characteristics of Listeria?

Answer 9

• Survives and proliferates at refrigeration temperatures
• Higher case fatality rate than most other food-borne pathogens