Chlamydiae

Chlamydiae is a phylum of the bacteria domain. Development of such bacteria takes place completely within a cellular vacuole; they are hence termed intracellular bacteria. There are only four species identified as part of this phylum: Chlamydia psittaci, Chlamydia pecorum, Chlamydia trachomatis, and Chlamydia pneumoniæ. The latter two are human relates species: trachomatis is the famous sexually transmitted infection and pneumoniæ is a form of bacteria causing the disease Pneumonia.

The infect the individual in their first stage as an inactive particle called an infectious elementary body (EB), surviving extracellularly. After becoming cellularly internalised they become metabolically active reticulate bodies (RB). Further EBs are produced infecting surrounding cells.