Chlamydiae

Chlamydiae:
Important Properties:
1- Chlamydiae are obligate intracellular bacteria. They lack the ability to produce sufficient
energy to grow independently and therefore can grow only inside host cells.
2- They have a rigid cell wall but do not have a typical peptidoglycan layer. Their cell walls
resemble those of gram-negative bacteria but lack muramic acid.
3- Chlamydiae have a replicative cycle different from that of all other bacteria. The cycle begins
when the extracellular, metabolically inert, "sporelike" elementary body enters the cell and
reorganizes into a larger, metabolically active reticulate body. The latter undergoes repeated
binary fission to form daughter elementary bodies, which are released from the cell. Within cells,
the site of replication appears as an inclusion body, which can be stained and visualized
microscopically. These inclusions are useful in the identification of these organisms in the
clinical laboratory.
4- All chlamydiae share a group-specific lipopolysaccharide antigen, which is detected by
complement fixation tests. They also possess species-specific and immunotype-specific antigens
(proteins), which are detected by immunofluorescence. C. psittaci and C. pneumoniae each have
1 immunotype, whereas C. trachomatis has at least 15.