The Effect of Surface-Active Agents upon the Multiplication of Entamoeba Histolytica in Culture

Richard E. Reeves Department of Biochemistry, Louisiana State University School of Medicine, New Orleans, Louisiana

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Twelve surface-active agents were tested in MS-F cultures of the DKB strain of Entamoeba histolytica and all were found to be amebastatic at relatively low concentrations.

Anionic and non-ionic surface-active agents in sufficient concentration decrease the airliquid surface tension of the culture medium and suppress the multiplication of amebae. With many of these surfactants there is an abrupt break in the multiplication of amebae at about 44 dyne/cm, cultures having lower terminal surface tensions showing no multiplication.

Cationic surfactants suppress ameba multiplication at very low concentrations and may do so without significantly lowering the air-liquid surface tension of the culture fluid.

Cetyltrimethylammonium bromide was amebastatic at a concentration of 3 micrograms per ml. Of the substances investigated only emetine has been found to be effective at a lower concentration.

The surface tension of the standard control cultures was found to decrease from about 54 dyne/cm to about 48 cyne/cm due to the multiplication of amebae during the incubation period.

A possible relationship between surfactants in the intestinal contents and host resistance to amebic infection is considered.

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