|Class:||Chlamydiae Cavalier-Smith 2002|
|Order:||Chlamydiales Storz and Page 1971 emend. Everett et al. 1999|
Chlamydiae is a bacterial phylum and Class (biology) whose members are obligate intracellular pathogens. They are ovoid in shape. They have a peptidoglycan free cell wall and are susceptibile to various antimicrobial agents. All known chlamydiae only grow by infecting eukaryotic host cells. They are as small as or smaller than many viruses. Chlamydiae replicate inside the host cells and are termed intracellular. Most intracellular chlamydiae are located in an inclusion body or vacuole. Outside of cells they survive only as an extracellular infectious form. Chlamydiae can grow only where their host cells grow. Therefore, chlamydiae cannot be propagated in bacterial culture media in the clinical laboratory. Chlamydiae are most successfully isolated while still inside their host cell.
- History 1
- Nomenclature 2
- Genomics 3
- Phylogeny 4
- References 5
- External links 6
Chlamydia-like disease affecting the eyes of people was first described in ancient Chinese and Egyptian manuscripts. A modern description of chlamydia-like organisms was provided by Halberstaedrrter and von Prowazek in 1907. Chlamydial isolates cultured in the yolk sacs of embryonating eggs were obtained from a human pneumonitis outbreak in the late 1920s and early 1930s, and by the mid-20th century isolates had been obtained from dozens of vertebrate species. The term 'chlamydia' (a cloak) appeared in the literature in 1945, although other names continued to be used, including Bedsonia, Miyagawanella, ornithosis-, TRIC-, and PLT-agents.
In 1966, chlamydiae were recognized as bacteria and the genus Chlamydia was validated. The order Chlamydiales was created by Storz and Page in 1971. Between 1989 and 1999, new families, genera, and species were recognized. The phylum Chlamydiae was established in Bergey's Manual of Systematic Bacteriology.
By 2006, genetic data for over 350 chlamydial lineages had been reported, four chlamydial families had been recognized (Chlamydiaceae, Parachlamydiaceae, Simkaniaceae, and Waddliaceae), and another family had been proposed (Rhabdochlamydiaceae).
The chlamydiae form a unique bacterial evolutionary group that separated from other bacteria approximately a billion years ago. The species from this group can be distinguished from all other bacteria by the presence of conserved
- Chlamydiae.com, a comprehensive information source from Dr. Michael Ward (Professor of Medical Microbiology in the University of Southampton)
- Wyrick P (2000). "Intracellular survival by Chlamydia". Cell Microbiol 2 (4): 275–82.
- Malhotra M, Sood S, Mukherjee A, Muralidhar S, Bala M (September 2013). "Genital Chlamydia trachomatis: an update". Indian J. Med. Res. 138 (3): 303–16.
- Moulder J (1966). "The relation of the psittacosis group (Chlamydiae) to bacteria and viruses". Annu Rev Microbiol 20: 107–30.
- Storz J, Page LA (1971). "Taxonomy of the Chlamydiae: reasons for classifying organisms of the genus Chlamydia, family Chlamydiaceae, in a separate order, Chlamydiales ord. nov". International Journal of Systematic Bacteriology 21 (4): 332–334.
- Garrity GM, Boone DR (editors) (2001). Bergey's Manual of Systematic Bacteriology Volume 1: The Archaea and the Deeply Branching and Phototrophic Bacteria (2nd ed.). Springer.
- Everett K, Thao M, Horn M, Dyszynski G, Baumann P (2005). "Novel chlamydiae in whiteflies and scale insects: endosymbionts 'Candidatus Fritschea bemisiae' strain Falk and 'Candidatus Fritschea eriococci' strain Elm". Int J Syst Evol Microbiol 55 (Pt 4): 1581–7.
- Everett K, Bush R, Andersen A (1999). "Emended description of the order Chlamydiales, proposal of Parachlamydiaceae fam. nov. and Simkaniaceae fam. nov., each containing one monotypic genus, revised taxonomy of the family Chlamydiaceae, including a new genus and five new species, and standards for the identification of organisms". Int J Syst Bacteriol 49 (2): 415–40.
- Rurangirwa F, Dilbeck P, Crawford T, McGuire T, McElwain T (1999). "Analysis of the 16S rRNA gene of micro-organism WSU 86-1044 from an aborted bovine foetus reveals that it is a member of the order Chlamydiales: proposal of Waddliaceae fam. nov., Waddlia chondrophila gen. nov., sp. nov". Int J Syst Bacteriol 49 (2): 577–81.
- Greub G, Raoult D (2003). "History of the ADP/ATP-Translocase-Encoding Gene, a Parasitism Gene Transferred from a Chlamydiales Ancestor to Plants 1 Billion Years Ago". Appl Environ Microbiol 69 (9): 5530–5.
- Horn M, Collingro A, Schmitz-Esser S, Beier C, Purkhold U, Fartmann B, Brandt P, Nyakatura G, Droege M, Frishman D, Rattei T, Mewes H, Wagner M (2004). "Illuminating the evolutionary history of chlamydiae". Science 304 (5671): 728–30.
- Griffiths E, Petrich AK, Gupta RS (August 2005). "Conserved indels in essential proteins that are distinctive characteristics of Chlamydiales and provide novel means for their identification". Microbiology (Reading, Engl.) 151 (Pt 8): 2647–57.
- Gupta RS, Griffiths E (December 2006). "Chlamydiae-specific proteins and indels: novel tools for studies". Trends Microbiol. 14 (12): 527–35.
- Ward N, Rainey F, Hedlund B, Staley J, Ludwig W, Stackebrandt E (2000). "Comparative phylogenetic analyses of members of the order Planctomycetales and the division Verrucomicrobia: 23S rRNA gene sequence analysis supports the 16S rRNA gene sequence-derived phylogeny". Int J Syst Evol Microbiol 50 (6): 1965–72.
- Teeling H, Lombardot T, Bauer M, Ludwig W, Glöckner F (2004). "Evaluation of the phylogenetic position of the planctomycete 'Rhodopirellula baltica' SH 1 by means of concatenated ribosomal protein sequences, DNA-directed RNA polymerase subunit sequences and whole genome trees". Int J Syst Evol Microbiol 54 (Pt 3): 791–801.
- Griffiths E, Gupta RS (August 2007). "Phylogeny and shared conserved inserts in proteins provide evidence that Verrucomicrobia are the closest known free-living relatives of chlamydiae". Microbiology (Reading, Engl.) 153 (Pt 8): 2648–54.
- Corsaro D, Greub G (2006). "Pathogenic Potential of Novel Chlamydiae and Diagnostic Approaches to Infections Due to These Obligate Intracellular Bacteria". Clin Microbiol Rev 19 (2): 283–97.
- See the
- See the
♠ Strains found at the National Center for Biotechnology Information (NCBI) but not listed in the List of Prokaryotic names with Standing in Nomenclature (LSPN) ♥ Strains not lodged at National Center for Biotechnology Information (NCBI) and or listed in the List of Prokaryotic names with Standing in Nomenclature (LPSN)
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)  and the phylogeny is based on 16S rRNA-based LTP release 111 by The All-Species Living Tree Project 
- Chlamydia trachomatis, which causes the eye-disease trachoma and the sexually transmitted infection chlamydia;
- Chlamydophila pneumoniae, which causes a form of pneumonia;
- Chlamydophila psittaci, which causes psittacosis.
There are three described species of chlamydiae that commonly infect humans:
 The unique status of chlamydiae has enabled the use of DNA analysis for chlamydial diagnostics. of known strains within chlamydiae.phylogeny genes has provided a ribosomal RNA Comparison of