Free Living Amoebae as Contaminants in Monkey Kidney Tissue Culture

Abstract

Two strains of apparently the same free living amoebae were found to be spontaneous contaminants in monkey kidney tissue culture (TC). The TC technique proved to be a suitable method for cultivation of the amoebae in the absence of bacteria. Pure cultures of the amoeba were obtained in many cell lines. Both cysts and trophozoites were found in TC. In monkey kidney tissue culture, cysts were often found in the cytoplasm of the cells. One strain was subjected to 16 consecutive passages in monkey kidney tissue culture while the other had 12. The average titer for cytotoxic changes in TC was 104 to 105/1.0 ml. The cysts in the TC fluid survived at -50[degree]C for 8 months, although the titer was greatly reduced.