<prompt> Cyst phase does not exist in -Gardenella vaginalisTrichomonas vaginalisEntamoeba hystolyticaEntamoeba coli  <response>: 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. 