Entamoeba histolytica and Entamoeba dispar are two microscopically indistinguishable amoebae living in the human colon. The former is a pathogen, whereas the latter is a non-pathogenic commensal.
Using a model system of in vitro cocultures and PCR detection of the Entamoeba species, we found that the non-pathogenic species can rapidly outgrow the pathogen in xenic cultures.