Chlamydia

[Jessica]

Three species of Chlamydia cause human disease, including sexually transmitted diseases and respiratory infections. All are susceptible to macrolides (eg, azithromycin ), tetracyclines (eg, doxycycline ), and fluoroquinolones.
Chlamydiae are nonmotile, obligate intracellular bacteria. They contain DNA, RNA, and ribosomes and make their own proteins and nucleic acids. However, they depend on the host cell for 3 of their 4 nucleoside triphosphates and use host adenosine triphosphate (ATP) to synthesize chlamydial protein.
The genus Chlamydia now contains 12 species; 3 of them cause human disease:

Chlamydia trachomatis
Chlamydia pneumoniae
Chlamydia psittaci

Chlamydial species can cause persistent infection, which is often subclinical.

[Lanell]

A very small parasitic bacterium which, like a virus, requires the biochemical mechanisms of another cell in order to reproduce. Bacteria of this type cause various diseases including trachoma, psittacosis, and nonspecific urethritis.