Refrigeration of the specimen for several months may enhance isolation of which organism?

Refrigeration of a specimen can effectively enhance the isolation of organisms that can survive and thrive in cooler temperatures. Listeria monocytogenes is a psychrotrophic bacterium, meaning it can grow at refrigeration temperatures. It is known for its resilience in colder environments, allowing it to remain viable and potentially proliferate over extended periods when refrigerated. This characteristic is particularly important in clinical settings, as Listeria can be present in food products and may persist in environments like food-processing plants, making it crucial for isolating this pathogen.

In contrast, the other organisms listed do not have the same capability to survive extended refrigeration or have different isolation needs. Psychrophilic blood bank contaminants, while they might tolerate cold, would not specifically thrive or be enhanced in growth from extended refrigeration. Neisseria meningitidis is typically isolated from warm environments, particularly the human nasopharynx, and does not grow well at refrigeration temperatures. Actinomyces species, although they can be found in various environments, are not predominantly known for their growth or viability under refrigeration for prolonged periods.