<unk> sis is caused by the organism Chlamydia<unk> . Chlamydia is understood to be a Gram-negative bacterium belonging to the genus Chlamydia or Chlamydophila in the family of Chlamydiaceae  together with  Parachlamydiaceae, Waddliaceae and Simkaniaceae in the order Chlamydiales, class and phylum Chlamydiae. Chlamydiales are obligate intracellular infectious agents in eukaryotic cells characterized by a unique developmental replication cycle.
Chlamydophila psittaci
Bartonella henselae
Klebsiella rhinoscleromatis
Chlamydophila trachomatis
Mycoplasma
Naegleria fowleri
Mycobacterium xenopi
Toxoplasma gondii