Domain Bacteria Woese et al. 1990
   Phylum Proteobacteria Garrity and Holt 2001 see Phylum Proteobacteria Garrity et al. 2005
     Class "Epsilonproteobacteria" nom. inval. see Class Epsilonproteobacteria Garrity et al. 2006
       Order "Campylobacterales" nom. inval. see Order Campylobacterales Garrity et al. 2006
         1 Family Campylobacteraceae Vandamme and De Ley 1991
         2 Family "Helicobacteraceae" nom. inval. see Family Helicobacteraceae Garrity et al. 2006