Cultivation of Entamoeba Histolytica and Entamoeba Histolytica-like Strains at Reduced Temperature and Behavior of the Amebae in Diluted Media

Abstract

Summary This paper reports studies on 8 strains of Entamoeba histolytica and 5 strains of E. histolytica-like amebae, with regard to their ability to grow at reduced temperatures and in diluted medium. The 8 E. histolytica strains did not tolerate low temperature or hypotonic medium. The 5 E. histolytica-like strains (of which 2 are newly described) multiplied as active trophozoites at temperatures as low as 10°C., and in 1:32 or 1:64 dilution of medium with distilled water, without need for adaptation through intermediate steps. In hypotonic solutions contracting vacuoles formed in trophozoites, and mature 4-nucleated cysts eventually developed. Five of the 8 E. histolytica strains were derived from patients with invasive amebiasis, while all 5 E. histolytica-like strains came from human hosts with records of few or no gastrointestinal symptoms.