A 73-year-old man is brought to the emergency department because of fever, headaches, and confusion for the past 24 hours. Three years ago, he underwent heart transplantation because of congestive heart failure. His temperature is 38.1°C (100.5°F). He is oriented only to person. Physical examination shows nuchal rigidity. A cerebrospinal fluid culture on blood agar grows colonies of a gram-positive bacillus surrounded by a narrow transparent rim. Which of the following processes is most important for eliminating these bacteria from the body?

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Quizplus · Accepted Answer

Eductional Objective: Listeria monocytogenes is a facultative, intracellular, gram-positive rod that produces a very narrow zone of beta hemolysis on blood agar, shows tumbling motility at room temperature, and can grow at refrigerated temperatures.  Intracellular pathogens such as Listeria are largely eliminated by the cell-mediated immune response (eg, T-cells, macrophages, cytokines).  Patients with impaired cell-mediated immunity are at risk for invasive Listeria infections.

A 73-Year-Old Man Is Brought to the Emergency Department Because