Which statement about C. burnetii best captures its intracellular lifestyle?

Which statement about C. burnetii best captures its intracellular lifestyle?

• A. It is a strictly extracellular organism
• B. It cannot survive inside macrophages
• C. It is a facultative intracellular coccobacillus
• D. It is a Gram-negative diplococcus

Answer: (C)

Coxiella burnetii has a lifestyle that thrives inside host cells while also being able to persist outside them. It specifically replicates within the phagolysosome of macrophages, an acidic intracellular compartment, which shows its adaptation to an intracellular niche. At the same time, it forms environmentally stable forms that allow survival outside a host, enabling transmission and persistence in the environment. This combination—living inside cells but not exclusively so—defines it as a facultative intracellular organism. Morphologically, it is a Gram‑negative coccobacillus, not a Gram‑negative diplococcus.

Coxiella burnetii has a lifestyle that thrives inside host cells while also being able to persist outside them. It specifically replicates within the phagolysosome of macrophages, an acidic intracellular compartment, which shows its adaptation to an intracellular niche. At the same time, it forms environmentally stable forms that allow survival outside a host, enabling transmission and persistence in the environment. This combination—living inside cells but not exclusively so—defines it as a facultative intracellular organism. Morphologically, it is a Gram‑negative coccobacillus, not a Gram‑negative diplococcus.