After inhalation, which cell type is involved in the intracellular survival of C. burnetii?

• A. Erythrocytes are the primary reservoir
• B. Monocytes are involved in intracellular survival
• C. Neurons are infected
• D. Platelets mediate persistence

Answer: (B)

Coxiella burnetii is an obligate intracellular bacterium that relies on cells of the mononuclear phagocyte system as its niche. After inhalation, it’s taken up by alveolar macrophages and then survives and replicates inside the phagolysosome, with monocytes in the bloodstream carrying the bacteria to reticuloendothelial tissues. This dependence on monocytes/macrophages is why this cell type is the best choice. Erythrocytes don’t perform phagocytosis and don’t serve as intracellular reservoirs; neurons aren’t typical hosts; platelets aren’t known to harbor intracellular survival of this organism.