2. Two forms of the organism are needed for infection and disease to occur: the infectious, extracellular form called an elementary body (EB) and the noninfectious but metabolically active intracellular form called a reticulate body (RB).

 

3. The elementary body, a small, infectious, but non-replicating particle found in secretions, attaches to and enters a host cell, such as an endocervical or urethral columnar epithelial cell. The contact with the host cell membrane causes the elementary body to induce its own endocytosis.

 

4. Within eight hours, the now-intracellular elementary body interacts with glycogen and transforms into a reticulate body, which begins to multiply within an isolated intracellular structure referred to as an inclusion. The reticulate bodies are the noninfectious replicating form.

 

5. Within 48 hours, some of the reticulate bodies begin to reorganize back to elementary bodies.

 

6. Within 72 hours, most of reticulate bodies have transitioned back to elementary bodies and the inclusion either undergoes lysis at the host cell wall or the intact inclusion (containing numerous elementary bodies) is released into the extracellular space.

 

7. Regardless of whether the inclusion undergoes lysis or is extruded intact, the elementary bodies are released to infect adjacent cells or to be transmitted to and infect another person.

-the most sensitive tests (preferred test)
-can be performed on endocervical, urethral, vaginal, pharyngeal, rectal, or urine samples
-On wet mount, a finding of leukorrhea has been associated with chlamydial and gonococcal infections of the cervix.

-The specimen is suspended in fluid and centrifuged on McCoy cells pretreated with cycloheximide. After 48-78 hours cytoplasmic inclusions is seen.
-It is unreliable for diagnostic purpose

-If positive ,the EBs stain will be seen as bright yellow green dots and can be obtained within a few hours.
-Extremely specific but not sensitive for asymptomatic infections.

•Size: 0.2 to 0.3 micrometer

•RNA: DNA 1:1

•contains rigid trilaminar cell wall

•Can be detected by Gram-staining

•Resistant to typsin digestion

•Metabolically inactive

•No replication

•Size: 1 micrometer

•RNA: DNA 3:1

•have no rigid cell wall, still membrane bound

•Can be detected by Giemsa 

•Sensitive to typsin digestion 

•Metabolically active

•Replication by binary fission

•Many serovars; A to C, D to K and L1, L2 and L3

•Obligate gram negative coccoid parasite

•Contain DNA, RNA and ribosomes

•Lack ATP

•Have a cell wall but peptidoglycan and N-acetylmuramic acid is absent

•Non-motile in nature