Chlamydia

What you should know:

Chlamydias are Gram-negative rods that are among the smallest bacteria known  (as small as 0.2 mm). They are chemoheterotrophs with an obligate intracellular life cycle. Some strains of this pathogen can be sexually transmitted. Chlamydia cause diseases such as urethritis, psittacosis, trachoma, and pneumonia

Classification: 

Domain Bacteria

    Phylum Chlamydiae

        Class Chlamidiae 

Bergey's Manual Volume 4: The Bacteroidetes, Spirochaetes, Tenericutes (Mollicutes), Acidobacteria, Fibrobacteres, Fusobacteria, Dictyoglomi, Gemmatimonadetes, Lentisphaerae, Verrucomicrobia, Chlamydiae, and Planctomycetes