Coxiella burnetii is an
obligate intracellular bacterial pathogen, and is the causative agent of
Q fever. The genus
Coxiella is morphologically similar to
Rickettsia, but with a variety of genetic and physiological differences.
C. burnetii is a small
Gram-negative bacterium that is highly resistant to environmental stresses such as high temperature, osmotic pressure, and ultraviolet light. These characteristics are attributed to a small cell variant form of the organism that is part of a biphasic developmental cycle, including a more metabolically and replicatively active large cell variant form. It can survive standard disinfectants, and is resistant to many other environmental changes like those presented in the
phagolysosome.