The Chlamydiae

Abstract

Chlamydiae are small, gram-negative eubacteria (Weisburg et al., 1986) that grow intracellulary only. Due to their unique developmental cycle, chlamydiae are recognized in their own order, i.e., Chlamydiales. This order consists of one family, Chlamydiaceae, and of one genus, Chlamydia, with two characterized species, C. psittaci and C. trachomatis. The organisms now included in the genus Chlamydia were earlier called Miyagawanella and Bedsonia (Page, 1974; Moulder et al., 1984). For some decades TRIC (trachoma inclusion conjunctivitis) was used as a designation for the non-LGV C. trachomatis organisms. The so-called TWAR chlamydiae may form a new, third species (with the tentative name C. pneumoniae) (Fig. 3). The two established species can be differentiated on the basis of inclusion type and sensitivity to sulfonamides. (C. trachomatis inclusions contain glycogen whereas C. psittaci inclusions do not; C. trachomatis is more susceptible to sulfonamides than C. psittaci.)