C. burnetii is a facultative intracellular coccobacillus. Once inhaled and trapped in the lungs, intracellular survival in what cell type is important in the pathogenesis of Q fever?

C. burnetii is a facultative intracellular coccobacillus. Once inhaled and trapped in the lungs, intracellular survival in what cell type is important in the pathogenesis of Q fever?

• A. Monocytes
• B. Neutrophils
• C. Erythrocytes
• D. Platelets

Answer: (A)

Coxiella burnetii relies on living and multiplying inside macrophage-lineage cells. After inhalation, it targets alveolar macrophages and then uses the macrophage/monocyte as its niche, thriving in the phagolysosome and enabling long-range dissemination through the bloodstream to organs like the liver and spleen. This intracellular survival in monocytes is what drives the pathogenesis of Q fever. Among the options, monocytes fit this niche best because they differentiate into macrophages, which are the primary cells Coxiella infects and replicates within during disease. Neutrophils are rapid, short-lived responders that don’t serve as a replication niche for Coxiella. Erythrocytes lack nuclei and phagolysosomal compartments, so they aren’t hosts for intracellular replication. Platelets are not host cells for bacterial replication either.

Coxiella burnetii relies on living and multiplying inside macrophage-lineage cells. After inhalation, it targets alveolar macrophages and then uses the macrophage/monocyte as its niche, thriving in the phagolysosome and enabling long-range dissemination through the bloodstream to organs like the liver and spleen. This intracellular survival in monocytes is what drives the pathogenesis of Q fever.

Among the options, monocytes fit this niche best because they differentiate into macrophages, which are the primary cells Coxiella infects and replicates within during disease. Neutrophils are rapid, short-lived responders that don’t serve as a replication niche for Coxiella. Erythrocytes lack nuclei and phagolysosomal compartments, so they aren’t hosts for intracellular replication. Platelets are not host cells for bacterial replication either.