**3. Staining properties**

Chlamydia has different staining characteristics. Elementary bodies are stained purple on blue-stained host cell cytoplasm with Giemsa stain. Reticular bodies are stained blue. Chlamydia stains with gram-negative or variable staining. Therefore, the gram stain is useless in identification. Chlamydia particles and inclusions (with group-specific, species-specific, or serovar-specific antibodies) are stained bright yellow-green by the immunofluorescence dye method. In culture, McCoy cells are stained with iodide when growth occurs. *C. trachomatis* appears with brown-stained inclusions on a yellow background [11].
