Domain Bacteria Woese et al. 1990
   Phylum Actinobacteria Garrity and Holt 2001
     Class Actinobacteria Stackebrandt et al. 1997
       Subclass Actinobacteridae Stackebrandt et al. 1997 see Class Actinobacteria Stackebrandt et al. 1997
         Order Bifidobacteriales Stackebrandt et al. 1997
           Family Bifidobacteriaceae Stackebrandt et al. 1997
             Genus Gardnerella Greenwood and Pickett 1980