Causal AgentThe taxonomic classific

Causal Agent
The taxonomic classification of Blastocystis hominis is mired in controversy. It has been previously considered as yeasts, fungi, or ameboid, flagellated, or sporozoan protozoa. Recently, however, based on molecular studies, especially dealing with the sequence information on the complete SSUrRNA gene, B. hominis has been placed within an informal group, the stramenopiles (Silberman et al. 1996). Stramenopiles are defined, based on molecular phylogenies, as a heterogeneous evolutionary assemblage of unicellular and multicellular protists including brown algae, diatoms, chrysophytes, water molds, slime nets, etc. (Patterson, 1994). Cavalier-Smith (1998) considers stramenopiles to be identical to his infrakingdom Heterokonta under the kingdom Chromista. Therefore, according to Cavalier-Smith, B. hominis is a heterokontid chromista.