Bacteria-free Entamoeba invadens

Abstract

Two strains of Entamoeba invadens have been growing in vitro, on serial transfer, for more than two years in a bacteria-free medium. The culture medium used initially¹ has been simplified and now consists of 10 ml. of 0.75 per cent saline solution to which is added a slice of hamster liver, and the culture is sealed with a layer of petroleum jelly. Liver slices from rats, rabbits, guinea pigs, chickens, pigs and hamsters, have been tested and found to support good growth of the bacteria-free E. invadens. The liver cubes used measure 2–4 mm. a side. Limited experiments demonstrate that chicken-breast muscle and rat-heart muscle will also support in vitro growth of amœbæ in the absence of bacteria.