VetBact logo


Swedish University of Agricultural Sciences

Veterinary bacteriology: information about important bacteria
Veterinary bacteriology

Species/Subspecies: Rickettsia rickettsii
Category: Motile
Etymology: Genus namn: Named after Howard T. Ricketts, who showed which organism caused Rocky Mountain spotted fever, which resulted in his death
Species epithet: see Genus namn.
Significance:  [Of minor importance]   
Type Strain: Smith = ATCC VR-149.
Macromorphology (smell): Cannot be cultivated on cell free substrates (for instance agar plates).
Micromorphology: Short (paired) motile rods (0.2-0.3 x 0.3-2 µm).R. rickettsia exhibits actin-based motility (see references 154 and 155 below).
Gram +/Gram -:G-
Metabolism: Aerobic
Fermentation of carbohydrates: Is not used for identification of Rickettsia spp.
Spec. Char.: Is obligate intracellular because the plasma membrane is leaky and the bacteria require correct osmolarity and constant supply of nutrients.
Vector: American dog tick or wood tick (Dermacentor variabilis) and Rocky Mountain wood tick (Dermacentor andersoni).
Disease:Rocky Mountain spotted fever
Hosts: Dog, man
Clinical Picture:
Genome Sequence:
Acc-noStrainSize (bp)Genome
NC_009882 Sheila Smith 1 257 710 1c + 0 

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
L36217 1440 

About 30 species have been described within the genus Ricketsia. This genus is relatively closely related to other genera within the orderRickettsialas (Anaplasma, Ehrlichia and Neorickettsia).
Legislation: R. rickettsia belongs to category C as a potential bioterrorism agent according to NIAID
Comment:Intracellular in endothelial cells where it is primarely growing freely in the cytoplasm. An evolutionary interesting bacterium, because its ancestors invaded cells and formed the mitochondria by endosymbiosis. Can use ATP from the hostcell, but also synthesize ATP by oxidative phosphorylation.
Reference(s): No. 154, 155


New names of bacterial phyla

The taxonomic category phylum was previously not regulated by the International Code of Nomenclature of Prokaryotes (ICNP), but now this has changed and it was decided to revise the names of bacterial phyla. All phyla must be written in italics (which has been done on VetBact also before) and have the ending -ota.

Published 2023-03-01. Read more...
The taxonomy of chlamydias

Species within the family Chlamydiaceae were previously divided into two genera Chlamydia and Chlamydophila. However, the differences between these two genera were not that great and many research groups have not accepted this division. Therefore, the genus Chlamydophila has been returned to the genus Chlamydia and this change has now been incorporated in VetBact

Published 2023-03-15. Read more...

Recently Updated

Recent blog posts

Most recent comment

Swedish University of Agricultural Sciences