Question

Which is the responsible organism for listeriosis?

• A. Listeria ivanovii
• B. L. grandensis
• C. L. monocytogenes
• D. L. seeligeri

Hint:

Listeria monocytogenes is a key pathogen monitored in ready-to-eat and cold-smoked seafood because of its unique ability to grow at refrigeration temperatures ($4\text{^\circ C}$).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Listeriosis is a serious foodborne illness caused by eating food contaminated with pathogenic bacteria of the genus Listeria.
This pathogen is a concern in ready-to-eat seafood, cold-smoked fish, and crab meat because it can survive and grow at refrigeration temperatures.
Detailed Explanation:
The genus Listeria contains several species, but only one is a major human pathogen:
- {Listeria monocytogenes (3) is the causative agent of human listeriosis.
It is a psychrotrophic, gram-positive, rod-shaped bacterium.
Because it can tolerate high salt concentrations and grow at low temperatures ($4\text{^\circ C}$), it can persist in cold-storage and processing environments, making it a critical pathogen in seafood safety.
It poses a risk to pregnant women, newborns, and immunocompromised individuals.
- Listeria ivanovii (1) is primarily an animal pathogen (mostly affecting sheep and goats) and rarely infects humans.
- Listeria seeligeri (4) and others are generally considered non-pathogenic environmental species.

Step 2: Final Answer:
The organism responsible for causing listeriosis in humans is Listeria monocytogenes.