What unique growth characteristic does Listeria monocytogenes possess?

Listeria monocytogenes has the unique growth characteristic of being able to grow at refrigerator temperatures, which distinguishes it from many other bacteria that typically thrive only at higher temperatures. This ability enables L. monocytogenes to survive and multiply in cold environments, such as those found in refrigerated foods, posing a significant risk for foodborne illness.

The capacity to grow at temperatures as low as 0°C to 4°C is particularly concerning for food safety, as it allows this pathogen to survive in chilled products like deli meats, unpasteurized dairy products, and even some ready-to-eat meals. This characteristic highlights the importance of proper food handling and storage practices to prevent listeriosis, especially for vulnerable populations such as pregnant women, newborns, the elderly, and immunocompromised individuals.

Other characteristics mentioned in the question do not accurately represent Listeria monocytogenes. For instance, it is not catalase negative but rather catalase positive. It is not strictly a human pathogen, as it can also infect animals, and it is not a gram-negative coccus; Listeria monocytogenes is a gram-positive bacterium and typically exhibits a bacillus shape.