Effects of Bacteriophage Upon Cultures of Entamoeba Histolytica. ∗

Abstract

The cultivation of Entamoeba histolytica has been made of practical and almost routine laboratory usefulness through the Boeck and Drbohlav 1 method of procuring cultures and the modification of Dobell and Laidlaw 2 has enhanced its success. However, the maintenance of continuous generations is often impaired and the strains frequently lost through the concurrent bacterial growth. As Dobell and Laidlaw have pointed out, the conjoint protozoa and schizomycetes microorganisms may attain an adaptation or adjustment that makes the amoebic growth luxuriant and the propagation of the culture simple. However, in continuing strains through many generations, the contamination or bacterial overgrowth feature is a most annoying factor and often threatens to destroy or actually causes the loss of the Entamoeba culture. As far as known the cultures of amoeba obtained by this method are always accompanied by bacterial growth and these accompanying microorganisms are regarded by many as obligatory commensurable or symbionts to the protozoal culture. Many efforts have been made, however, to reduce the bacterial contamination both as regards numbers and species. Since nearly all cultures have been obtained from the intestinal lesions, the bacterial accompaniment is naturally extensive.

Dobell and Laidlaw's modification of cultivation includes a weak solution of Acriflavine for the purpose of inhibiting overgrowth of bacteria especially of the starch splitting variety. This chemical must, however, be used in very weak strengths as otherwise it will destroy the amoebla themselves. In our hands the bacterial growth was only slightly influenced by these weak solutions, although the rice starch was better preserved.

In the present experiments the employment of bacteriophage in conjunction with the cultivation of Entamoeba histolytica was carried out with the view to inhibiting the bacterial growth occurring in the supernatant fluid medium.