Current knowledge on phylogeny and taxonomy of Rickettsia spp.

Due to improved diagnostic methods and increased interest, the number of representatives of the genus Rickettsia has increased dramatically over the past 20 years, with 25 currently validated species. These arthropod-associated intracellular bacteria are now recognized in all parts of the world. The comparison of the phylogenic organizations obtained from the study of several genes with different functions, and more recently from genomic sequences, provided basis to establish a reliable taxonomy of the bacteria induded in the genus Rickettsia. These data were incorporated into polyphasic consensus guidelines that provide clear recommendations for the taxonomic classification and nomenclature of rickettsiae and rickettsial diseases.