Cyst phase does not exist in -
Gardnerella is a genus of Gram-variable-staining facultative anaerobic bacteria of which G. vaginalis is the only species. The organisms are small nonspore-forming, nonmotile coccobacilli.
Gardenella vaginalis
Trichomonas vaginalis
Entamoeba hystolytica
Entamoeba coli
parasitology