Coxiella burnetii (C. burnetii)

Coxiella burnetii is a small, Gram-negative, pleomorphic, obligately intracellular bacterium of the class Gammaproteobacteria, order Legionellales. It is the etiological agent of Q fever, causing both acute and chronic infections in humans and animals. The bacterium primarily infects monocytes/macrophages and replicates within a specialized vacuole resembling a phagolysosome. It has a biphasic life cycle with environmentally resistant small cell variants and metabolically active large cell variants. Disease transmission typically occurs via aerosolized particles from infected animals or animal products. Because of its very low infectious dose, environmental stability, and potential for airborne spread, C. burnetii is considered a possible agent of bioterrorism. Treatment relies on prolonged antibiotic regimens, often with doxycycline and hydroxychloroquine, and preventive vaccination is available but limited by strong reactogenicity in previously sensitized individuals.

Other names

Nine Mile agentQ fever agentC. burnetii

Antibiotics: Inhibit bacterial protein synthesis or DNA replication (e.g., doxycycline inhibits the 30S ribosomal subunit, rifampin inhibits RNA polymerase). Host-directed drugs: Alter host cell signaling or immune responses to inhibit bacterial replication (not direct action on the bacterium itself).