<unk>  is a bacterial phylum whose members are obligate intracellular pathogens. Many<unk>  coexist in an asymptomatic state within specific hosts, and it is widely believed that these hosts provide a natural reservoir for these species.
All<unk>  grow by infecting eukaryotic host cells.  They are as small or smaller than many viruses.  Inside the cells<unk>  take on an intracellular replicative form; outside of cells they survive only in an extracellular infectious form.<unk>  can be grown only where their host cells grow, leading to two consequences in the laboratory:<unk>  cannot be propagated in bacterial culture media, and<unk>  are most successfully isolated while still inside the host cell.
Cavalier-Smith has postulated that the<unk>  fall into the clade Planctobacteria in the larger clade Gracilicutes.
Chlamydiae
Microsporidia
Amoebozoa
Bacillus
Plasmodium
Spirochaete
Sporophyte
Monilethrix