American pathologist Howard Taylor Ricketts (1871-1910) discovered the unique pathogen of Rocky Mountain typhus in 1909 and was killed by it, hence the name Ricketsia or Ricketsia. Rickettsia is a Gram negative bacterium, which is a type of obligate G prokaryote that parasitizes eukaryotic cells and is close to bacteria, between bacteria and viruses. It is generally spherical or rod-shaped. Rickettsia is mainly found in arthropods and often causes Q fever, Rocky Mountain spotted fever, or typhoid fever. It can be displayed through staining techniques such as Gram, Giemsa, Gimenez, Macchiavelo, etc.

The Rickettsia Staining Kit (Modified Macchiavello Method) has been improved by Culling to stain Rickettsia and certain viral inclusion bodies red, with bright staining and sharp contrast. This reagent is only used in the field of scientific research and is not suitable for clinical diagnosis or other purposes.