Increasing diversity within Chlamydiae

Crit Rev Microbiol. 2003;29(1):37-78. doi: 10.1080/713610404.


In recent years, 16S ribosomal DNA analyses has allowed the recognition of new chlamydia organisms, requiring the creation of new species, genera, and families within this unique, deep lineage of prokaryotes. The trachoma and psittaci groups chlamydiae are now recognized as separate genera, Chlamydia and Chlamydophila, respectively, and biovars of each group have been elevated to the species rank. Simkania and Parachlamydia have been associated with human respiratory infections, while Waddlia seems to be implicated in abortion in bovins. DNA amplification studies targeting the 16S rDNA have revealed a richer diversity within chlamydiae, identifying new lineages from both environmental and clinical samples. Further studies will be of interest to both examine the ecology and evaluate the clinical importance of these novel chlamydiae. Herein, we provide a summary of literature and our data about the novel chlamydial lineages.

Publication types

  • Review

MeSH terms

  • Chlamydia / classification
  • Chlamydia / genetics*
  • Chlamydia Infections / microbiology
  • Chlamydiales / genetics
  • Genetic Variation*
  • Humans
  • Models, Genetic
  • Phylogeny
  • RNA, Ribosomal, 16S / analysis
  • Sequence Analysis, DNA


  • RNA, Ribosomal, 16S