High Quality Content by WIKIPEDIA articles! 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 are small Gram-negative bacteria that are highly resistant to environmental stresses such as high temperature, osmotic pressure, and ultraviolet light. These characteristics are attributed to a small cell variant (SCV) form of the organism that is part of a biphasic developmental cycle including a more metabolically and replicatively active large cell variant (LCV) form. It can survive standard disinfectants, and is resistant to many other environmental changes like those presented in the phagolysosome.